Information

Is there anyway from which we can measure the viscosity of honey using a refractometer?


Is it possible to use a refractometer to measure the viscosity of honey because as we know, a refractometer is used to measure moisture and therefore water influences the viscosity of honey so is there a way that we can use to measure the viscosity of honey that way or using any other method apart from time since time has a high percentage of uncertainty?


Theoretically, if refractive index and viscosity are both simply functions of moisture content, you should be able to use one to approximate the other using an empirical standard curve. However, based on this paper, it looks like the relationship between moisture content and viscosity at 25C can vary quite a bit between different types of honey, expecially down below ~18% moisture. So I'd be pretty hesitant to rely on refractive index for acurate viscosity measurements unless you first rigerously validate your methodolgy against empirical viscosity measurements.


Marble Race – In Liquid!


Have you ever tried to squeeze honey or syrup out of a bottle at breakfast on a cold winter morning? Do you notice that it's harder to do that than on a hot summer day? As the liquid gets colder, its viscosity, or resistance to flow, increases. Viscosity is a properly of liquids that can be hugely important in wildly different applications – from how the syrup flows out of your bottle, to how blood flows through the human body, to how lava flows out of a volcano. In this project you will learn a little bit about viscosity using some liquids you already have in your kitchen.


1 Answer 1

I suppose you would cool it back before measurement, otherwise it would be measuring of temperature dependency of honey refraction index.

There would be change, it is the way how bees evaporate the excessive water to make honey stable. Obviously, it would be function of both temperature and time. As honey is very viscous, loosing water would be very slow in bulk volume and also place dependent, approximately following the 2nd Fick's law, unless being mixed.

But $60$ or $pu<80 ^circ C>$ is ridiculous, as it would not be honey any more, but just thick solution of fructose and glukose + some minor components. If honey is heated to dissolve crystallized sugars, it is recommended not to heat it more than $pu<40 ^circ C>$ .


Newtonian vs. Non-Newtonian Fluids

Isaac Newton, the man to discover this formula, thought that, at a given temperature and shear stress, the viscosity of a fluid would remain constant regardless of changes to the shear rate.

He was only partly right. A few fluids, such as water and honey, do behave this way. We call these fluids Newtonian fluids. Most fluids, however, have viscosities that fluctuate depending on the shear rate. These are called Non-Newtonian fluids.

There are five types of non-Newtonian fluids: thixotropic, rheopectic, pseudoplastic, dilatant, and plastic. Different considerations are required when measuring each of these fluid types.


Processing Honey: A Closer Look

Diets abound with notions that are as varied as the people expounding their virtues. This has put honey on some food hit lists being described as “just another sugar.” Nothing could be further from the truth.

Along with its antibacterial and antifungal properties, honey has been shown in multiple scientific and medical studies to have numerous health benefits. Honey contains over 180 substances, some of which allow our bodies to use it very differently than other carbohydrates. It is not “just another sugar.”

How good honey is for us, or whether it is any good at all, not only depends on how we use it, but also on how we process and store it.

This article will explore some of the chemistry of honey and how it can be affected by temperature, moisture, filtration and more. There are many pros and cons in honey processing, and knowledge of what we are dealing with can help us do a better job.

Temperature and Its Effect on Honey

For better or for worse, heat is often used in honey processing

Most operations handling more than a few buckets usually use heat in one form or another, even if it simply means warming honey to facilitate bottling. We should, however, be mindful that heat degrades honey and has an effect on many things including enzymes, color, flavor, and aroma.

Enzymes are important and all are affected by temperature. Merriam-Webster defines enzymes as complex proteins, produced by living cells, that catalyze or increase the rate of biochemical reactions. Simplistically put, enzymes can be thought of as energy. The presence of active enzymes is a part of what defines food that is alive and enzyme activity must be present in honey labeled “Raw.”

Let’s take a look at three notable enzymes in honey.

  • Invertase converts sucrose in nectar to glucose and fructose, which helps make nectar able to hold more solids thereby making it more stable.
  • Glucose Oxidase creates a chemical reaction which, among other things, lowers the pH of honey to an average of 3.9 and produces hydrogen peroxide. Both of these help stabilize nectar while ripening and contribute to the antibacterial properties of honey.
  • Diastase , as with all enzymes, is destroyed by heat, and because its activity is easily measured, it has been used by some importers and packers to tell how much heat honey has been exposed to.

“Honey absorbs moisture in a high humidity environment.”

The effects of heat on an enzyme are commonly measured by the time it takes to reduce half of the enzyme’s activity or its “half-life” at a given temperature. For instance, the half-life of diastase in honey is 1,000 days at 68 ˚F , 14 days at 122 ˚F , and 30 seconds at 176 ˚F . The other enzymes in honey are affected similarly. Enzyme activity stops when honey is held at freezing temperatures but returns when warmed back up. It does not return when destroyed by heat.

Two interesting side notes are that almost all the enzymes in honey are introduced by the bees, and all break down when liquefying crystallized honey in a microwave.

Flavor, Aroma and Color

Although the chemistry behind flavor and aroma is complex and not very well understood, they are a part of what defines high quality honey, and care should be taken not to cause unnecessary deterioration. One thing we know for sure is that they, along with color, are sensitive to high temperatures and deteriorate with time.

For instance, the color of honey is very slow to change when stored cold, but as it warms back up, the rate that honey darkens (and it will darken), will triple with every increase of 10 ˚F . Flavor and aroma deteriorate in a similar fashion when temperatures rise. Something as simple as prolonged warming in a bottling tank, a hot warehouse, or even a hot spot in your kitchen will have a degrading effect on honey.

Flavor, aroma, and color are especially affected in honey that is heated while containing debris such as dead bees, old comb containing cocoons, hive trash, and much of the menagerie of things that can come out of an extractor.

Some go so far as to say that honey processed with any heat at all can no longer be called raw. We might be careful not to rush to judgement here, however. This could turn into a debate with Mother Nature considering the fact that the top tiers of a beehive, in full sun, on a hot summer day, can get quite warm. I submit that care and moderation are the key for those that want to produce a good, wholesome product.

National Geographic has recently reported that honey found in an ancient tomb in Egypt was still edible, but I’m not sure I would want to be the one to eat it. Just because it hasn’t spoiled (fermented), and is still edible, doesn’t mean it’s still good food. Although not all honeys will deteriorate at the same rate, all eventually do. As with many foods, fresh is best and time is not your friend.

On another note, the internet has more than a few articles written by celebrated food experts stating that it is harmful to put honey in the refrigerator. This is not true. Cold honey degrades slower than warm honey and freezing temperatures are actually your best defense against deterioration.

Materials in Processing

Honey reacts with most metals

Because of its acidity, honey reacts with steel, iron, aluminum, galvanized metal, copper, tin, and more. Besides producing toxins, this can also affect taste and color. Although some are worse than others, steel and iron are considered especially bad for honey storage because they can rust and ruin honey. At least two exceptions to all this are silver and gold, but because we will probably not be manufacturing storage tanks out of silver or gold any time soon, I recommend food grade stainless steel as the next best, practical choice.

When using plastic in honey processing and storage, only food grade will do because other plastics can release excessive toxins. When bottling with plastic, polyethylene terephthalate (say that three times fast), better known as PETE plastic, is considered one of the best choices. PETE is clear and can be identified as having a number 1 in the triangle on the bottom of the container. High-density polyethylene, also known as HDPE plastic, is also commonly used and can be identified with a number two in the triangle.

In my opinion, glass is better than plastic for food, or anything else we ingest, but because plastic will almost always outsell glass when sitting side by side in a grocery store it’s hard not to offer it. We offer both and let the customer decide.

Moisture

Too much moisture in honey lowers quality

Although moisture may not be a big issue in arid areas like the southwest, it can be in high humidity, higher rainfall areas such as the east and southeast. Having a high moisture content in honey lowers quality and leads to fermentation. It’s actually easy to affect the moisture level in honey. It all revolves around a few basic facts.

Honey is hygroscopic, which means it will absorb moisture from a high humidity environment. It’s also hydrophilic, which means it will release moisture when there is low humidity. There is always a point where the moisture level in honey will balance out with the humidity level it is exposed to and that honey will cease to gain or lose water. For example, given enough time, honey that is exposed to air with a 60% humidity level will balance out with it at about 18.3% moisture content. This is not a bad place to be. Most honey will not ferment at this level although there are some that will. When exposed to 50% humidity, the moisture content in honey will lower to about 15.9%. This is a better place to be because no honey will ferment at this level and because it will have a thicker body, more character, and richer flavor, it would be considered a higher quality product. When continually exposed to 80% humidity, the moisture content in honey will eventually rise to 33.1%. No, that’s not a typo. Unless pasteurized, honey with a moisture content that high will create enough pressure from fermentation to bend a metal jar lid into a dome if the seal holds or create a heck of a mess from leakage or both.

Honey bees try to keep their hive between 50% and 60% humidity for good reason.

A good hygrometer can be a useful tool in a honey house.

Transporting, storing, uncapping, extracting, and the general handling of honey in a high humidity environment will absolutely add moisture to your honey. Doing the same in low humidity will have the opposite effect. A high quality hygrometer, which measures humidity, can be a good thing to have in a honey house. Cheap humidity gauges are usually inaccurate.

If you need to remove moisture from honey, it’s helpful to understand that honey has a very poor diffusion rate. If, for example, you were to use a fan to blow warm air across the top of a drum of thin honey only the top layer would dry because the effect will not migrate very far.

For most of us, unless you have a commercial honey dryer, it’s best to remove moisture before extracting. Honey supers can be placed in a warm, low humidity drying room which allows for a much greater surface area to be affected by warm, dry, moving air.

When removing moisture it is helpful to know that by simply raising the temperature in a given space, the relative humidity level will drop thereby increasing the drying effect.

If this is puzzling, remember that relative humidity is the amount of water vapor the air is holding compared to what it could hold if totally saturated at 100%. By increasing the temperature the amount of water vapor air can hold increases, so the relative humidity level, or current saturation level, goes down. This, along with the use of a dehumidifier and fans, can create a good, dry, low humidity environment for drying honey. Also, warm honey is easier to extract.

In our drying room at Blue Ridge Honey Co. we use two commercial dehumidifiers that run 24/7 during extracting season. Along with keeping the temperature 85 to 90 ˚F , this keeps the humidity level well below 30% even when it is as high as 100% outside. We move this air through the stacks of supers with industrial fans mounted on the ceiling and by doing so see a notable decrease in moisture content in just a few days. Although, contrary to popular belief, moisture can and does migrate through wax cappings, we try to harvest our honey supers with a small amount of comb still uncapped to achieve a quicker and greater overall moisture reduction. If you don’t have a refractometer for measuring moisture in honey you should get one. You may be surprised by what you find.

Yeast and Fermentation

Yeast can cause fermentation in high moisture honey

The yeasts found in honey are not the same as those used in bread and beer. They are tolerant of the high sugar concentration found in honey. The primary sources for these yeasts are flowers and soil and the bees bring it in freely.

Some bee books will tell you that fermentation will only occur in honey with a moisture content of 18.6% or higher. This is not always true. This number of 18.6% is dependent on the yeast spore count.

The yeast spore count in honey can range anywhere from one to tens of thousands per gram. Honey with a low spore count of one per gram will usually not ferment with a moisture content of up to 19%. Honey with a spore count of ten per gram needs to be 18.6% moisture or lower to be safe. A high spore count of 1,000 or more needs to have 17% moisture or lower, or fermentation can occur. For example, Mangrove honey with its low spore count is usually safe at 19% while Cabbage Palm honey with a higher than average count can sometimes ferment at 18%.

I can’t say how many times I have been surprised to have a barrel of honey that I thought was safe begin to show signs of fermentation. In my view, any hint of fermentation lowers the quality of honey and a high level completely ruins it.

Yeast is affected by temperature

Heat kills yeast and cold stops its activity.

One of the reasons some packers like to use heat in processing is that it stops fermentation in thin honey by killing the yeast. The yeast in honey will be dead in 8 hours when held at 125 ˚F , 30 minutes at 145 ˚F , and 1 minute at 160 ˚F . 100 ˚F or greater will slow fermentation, but honey stored for any time at these temperatures will show a noticeable deterioration of quality in other areas.

Be warned: if you think that killing the yeast in thin honey with heat will solve all of your fermentation problems going forward, think again. Yeast is everywhere. It is in your apiary, it is in your equipment, and it is airborne in your honey house.

“Producing a good quality product can be a challenge.”

Only if you heat honey in a sealed container or pour it hot into a container that will be sealed before it cools, will it be completely safe from fermentation. As soon as the container is opened again, if it is too thin, it is at risk. Again, yeast is everywhere.

If you do have to store thin honey and don’t want to use heat to kill the yeast, it can be stored cold. The activity of yeast in honey will stop when the temperature drops below 52 ˚F , but it will return when the temperature rises again.

Also worth knowing is that crystallized honey has a greater chance of fermenting than liquid. Not all of the sugars in honey will crystallize and the one that does (dextrose) has a lower solubility than the others. As it crystallizes, it will leave water behind thereby increasing the moisture content in the rest of the honey.

Numerous times I have had honey with borderline moisture content remain unfermented for some time only to have it ferment after crystallizing.

Why Crystallization Occurs

This drum of honey fermented after crystallizing and foamed over when warmed to liquefy.

Crystallization will occur in honey with a moderate to high percentage of dextrose

A 20% content of dextrose, also known as D-glucose, in honey is considered low and 40% is considered high. Honey with a 25% dextrose content or lower will generally not crystallize. Fresh honey containing 40% or more will begin the crystallization process faster than you can read this article.

I was once extracting a crop of Canola honey (which is high in dextrose) only to come back after a weekend off and find it setting up in the sump tank, pumps, and pipes. If you’re not paying attention, honey like this can quickly crystallize in the comb and become almost impossible to extract. I learned this one the hard way.

Honeys high in dextrose will crystallize hard, and those with a moderate percentage will crystallize soft. A little lower percentage may give you a slurry or a thick, cloudy body.

Age can also have an effect on the consistency of crystallized honey. Over time, the percentage of dextrose in crystallized honey can decrease as it slowly converts to other sugars. This can give the appearance of honey that seems to have separated liquid from solid, with the solid on the bottom. Given enough time, some crystallized honey can actually go almost completely liquid again. Of course, this honey would be quite old and undesirable in my view because it will have deteriorated in other ways.

Examples of honeys low in dextrose are Black Sage, Tupelo, and Sourwood. Titi, Cotton, and Canola are honeys high in dextrose and because of this are sometimes considered bakers grade or industrial grade.

Crystallization is affected by temperature

The optimum temperature for crystallization is around 57 ˚F . Those producing creamed honey can use this fact to their advantage. The farther the temperature moves either above or below this range, the less apt honey will be to crystallize. Honey will not crystallize at or below 32 ˚F . Honey that has already crystallized will begin to soften at 85 ˚F and begin to liquify between 100 ˚F and 104 ˚F .

Heat is used to dissolve crystals in fresh honey that can initiate the crystallization process. Heat is also used to facilitate micro filtering which can remove particles that act as a platform from which the crystallization process can begin. Even a particle of dust can act as a starting point. Thirty minutes at 145 ˚F will dissolve all crystals.

If you need a long shelf life without crystallization, heat will probably be needed.

Filtration

A filter with an 800 to 1000 micron mesh can remove large debris while allowing desirable substances through.

Filtration is considered a sin by some, and absolutely necessary by others

Honey labeled U.S. Grade A Fancy must be “free of defects that affect appearance and may not contain particles that affect clarity.” Although this standard for honey is not very well policed and can be highly misleading (much foreign honey is labeled US Grade A Fancy), many packers believe it adds consumer trust. Other than complying with this standard, there are other reasons many may not want particles in their honey. Besides crystallization and perceived shelf life issues, honey without particles can simply appear cleaner, brighter, and more attractive to consumers.

Of course, all of this requires fine filtering or “micro filtering” and there are those that feel this removes much of the “good stuff” in honey. That would include pollen, beeswax, and propolis particles, along with other substances considered desirable. Fine filtering also requires high heat to lower the viscosity (thickness) of honey so it can pass through a fine filtering medium. Honey handled like this should not be called raw although it often is.

The extreme opposite is honey sold as ultra raw. This honey is bottled straight out of the extractor, without any straining or settling at all and of course would contain a lot of foreign debris. While some would argue that the debris in freshly extracted honey is perfectly fine, even desirable, it’s important to keep in mind that not all debris is created equal. A bee wing or bee leg is one thing. A splinter or frame nail is quite another.

Just because I have product liability insurance doesn’t mean I want to use it. Some straining or settling is recommended. If you want to remove large, potentially harmful debris but allow much of the “good stuff” to remain, straining your honey through something like a coarse, 800 or 1000 micron filter will work.

Settling can also be helpful. Because honey is so heavy, light debris such as dead bees, wood, and wax will float to the top while heavy items such as nails, dirt, and wire will sink to the bottom.

To put filter mesh size in perspective most pollen particles run between 10 and 50 microns with one occasionally up to 100. In case you’re wondering, a micron, also known as a micrometer, is .001mm. or .000039 inch. The human eye generally cannot see a particle under 30 microns and a human hair is around 75.

Finally, on a personal note

I admit that when it comes to processing honey, producing a good quality product can sometimes be challenging. There will be mistakes made, and lessons learned the hard way. You may have to compete with people that have no problem with mislabeling and misleading customers. Let your quality and service speak for itself and remember it can take years to earn a good reputation, but it only takes a few seconds to lose it.

Bob Binnie is a commercial honey producer, honey packer and owns and operates Blue Ridge Honey Co. in Lakemont, Georgia along with his wife Suzette.


Looking for a non-volatile liquid less viscous than water

I have tried searching everywhere for a stable, non-volatile, bio-safe, low viscosity (< .8cST) fluid. Everything I have come across that is low viscosity is inflammable - acetone, ether, silicone oil, fuel, etc.

I have found some confusing things in my research. Acetone has a viscosity 3x less than water but weighs 2.5 times more. I would like to know how water weighs less but flows slower. Google says viscosity is from low intermolecular forces, but I do not know how to quantify those forces or how to find chemicals that match.

I am trying to make a science project that shows the principle of siphoning, but I want a lower viscosity liquid to show how viscosity effects flow rate. I am working with glass right now and PVC tubes, but I can change my materials based on whatever low viscosity liquid you can find.

Also if anyone knows anything about siphoning, viscosity or material chemistry please let me know if there is a database I can search or if you know chemical that is less viscous than water and meets my specifications.

Is there something I can add to water to lower the viscosity aside from heating? I do not want to have boiling water in my hands. I hear there are surfactants that lower the viscosity of water, but google says surfactants increase viscosity.


Ask an Expert: HELP. Viscosity Project

Firstly, i was wondering if there was anyway i could make this topic a little harder or if there is something related that is more challenging?

Also how would i conduct this experiment (what would the variables be?, what liquid could i use?)

Also how would i change the temperature of the liquid? can i use a bunsen burner to heat it?

Thankyou very much, any help at all is greatly appreciated!

Re: HELP. Viscosity Project

Post by yvetteds » Tue Feb 11, 2014 11:51 am

Hi -
It is an interesting topic and one way to make it higher level - more challenging, would be to investigate the change in viscosity of each liquid due to temperature - and then see what happens to those changes when you add solutes to your liquids making them solutions.

You will need to do some research yourself to decide which liquids (solvent) to test and what substances (solutes) you want to add to make solutions.

Then you can test the effect of temperature on the pure solvent and then the solutions.

Make sure you understand what the control factors need to be in your experiment and what your variables are.

Re: HELP. Viscosity Project

Post by SciB » Thu Feb 13, 2014 1:24 pm

I like Yvette’s idea of investigating the effects of various concentrations of solutes on the viscosity of a liquid. That is a bit more interesting than temperature since it is already known that temperature has a marked effect on viscosity: http://www.kayelaby.npl.co.uk/general_p . 2_2_3.html

One liquid that I can think of that is very viscous and safe to use is glycerol. You could make solutions of glycerol in water to reduce its viscosity and then add various concentrations of a solute such as sodium chloride and compare viscosities at different temperatures.

Honey would be a nice sweet liquid to test the viscosity of, but it is not a single chemical compound as glycerol is.

Measuring viscosity quantitatively is not easy. There are instruments that can be used to measure viscosity but they are very expensive and specialized. I looked up ways to do it cheaply and found some information. I have never done this so cannot say how reliable or correct these methods might be:
http://www.kayelaby.npl.co.uk/general_p . 2_2_3.html

See if any of these ideas appeals to you then repost and we will help you ask a good question with good experiments and controls.


Contents

Honey is produced by bees collecting nectar and honeydew for use as sugars consumed to support metabolism of muscle activity during foraging or to be stored as a long-term food supply. [13] [14] During foraging, bees access part of the nectar collected to support metabolic activity of flight muscles, with the majority of collected nectar destined for regurgitation, digestion, and storage as honey. [13] [15] In cold weather or when other food sources are scarce, adult and larval bees use stored honey as food. [14]

By contriving for honey bee swarms to nest in human-made hives, people have been able to semidomesticate the insects and harvest excess honey. In the hive or in a wild nest, the three types of bees are:

  • a single female queen bee
  • a seasonally variable number of male drone bees to fertilize new queens
  • 20,000 to 40,000 female worker bees[16]

Leaving the hive, a foraging bee collects sugar-rich flower nectar, sucking it through its proboscis and placing it in its proventriculus (honey stomach or crop), which lies just dorsal to its food stomach. In Apis mellifera, the honey stomach holds about 40 mg of nectar, or roughly 50% of the bee's unloaded weight, which can require over a thousand flowers and more than an hour to fill. The nectar generally begins with a water content of 70 to 80%. [17] Salivary enzymes and proteins from the bee's hypopharyngeal gland are added to the nectar to begin breaking down the sugars, raising the water content slightly. The forager bees then return to the hive, where they regurgitate and transfer nectar to the hive bees. The hive bees then use their honey stomachs to ingest and regurgitate the nectar, forming bubbles between their mandibles repeatedly until it is partially digested. The bubbles create a large surface area per volume and a portion of the water is removed through evaporation. [13] [15] [18] [19] The bee's digestive enzymes hydrolyze converts sucrose to a mixture of glucose and fructose, and break down other starches and proteins, increasing the acidity. [13] [15] [20]

The bees work together as a group with the regurgitation and digestion for as long as 20 minutes, passing the nectar from one bee to the next, until the product reaches the honeycombs in storage quality. [15] It is then placed in honeycomb cells and left unsealed while still high in water content (about 50 to 70%) and natural yeasts which, unchecked, would cause the sugars in the newly formed honey to ferment. [14] [21] [22] Bees are among the few insects that can generate large amounts of body heat, and the hive bees constantly regulate the hive temperature, either heating with their bodies or cooling with water evaporation, to maintain a fairly constant temperature of about 35 °C (95 °F) in the honey-storage areas. The process continues as hive bees flutter their wings constantly to circulate air and evaporate water from the honey to a content around 18%, raising the sugar concentration beyond the saturation point and preventing fermentation. [14] [15] The bees then cap the cells with wax to seal them. [15] As removed from the hive by a beekeeper, honey has a long shelf life and will not ferment if properly sealed. [14]

Some wasp species, such as Brachygastra lecheguana and Brachygastra mellifica found in South and Central America, are known to feed on nectar and produce honey. [23]

Some wasps, such as Polistes versicolor, consume honey, alternating between feeding on pollen in the middle of their lifecycles and feeding on honey, which can better provide for their energy needs. [24]

Collection

Honey is collected from wild bee colonies or from domesticated beehives. On average, a hive will produce about 29 kilograms (65 lb) of honey per year. [25] Wild bee nests are sometimes located by following a honeyguide bird.

To safely collect honey from a hive, beekeepers typically pacify the bees using a bee smoker. The smoke triggers a feeding instinct (an attempt to save the resources of the hive from a possible fire), making them less aggressive, and obscures the pheromones the bees use to communicate. The honeycomb is removed from the hive and the honey may be extracted from it either by crushing or by using a honey extractor. The honey is then usually filtered to remove beeswax and other debris.

Before the invention of removable frames, bee colonies were often sacrificed to conduct the harvest. The harvester would take all the available honey and replace the entire colony the next spring. Since the invention of removable frames, the principles of husbandry led most beekeepers to ensure that their bees have enough stores to survive the winter, [ citation needed ] either by leaving some honey in the beehive or by providing the colony with a honey substitute such as sugar water or crystalline sugar (often in the form of a "candyboard"). The amount of food necessary to survive the winter depends on the variety of bees and on the length and severity of local winters.

Many animal species are attracted to wild or domestic sources of honey. [26]

Preservation

Because of its composition and chemical properties, honey is suitable for long-term storage, and is easily assimilated even after long preservation. Honey, and objects immersed in honey, have been preserved for centuries. [27] [28] The key to preservation is limiting access to humidity. In its cured state, honey has a sufficiently high sugar content to inhibit fermentation. If exposed to moist air, its hydrophilic properties pull moisture into the honey, eventually diluting it to the point that fermentation can begin. [29]

The long shelf life of honey is attributed to an enzyme found in the stomach of bees. The bees mix glucose oxidase with expelled nectar they previously consumed, creating two byproducts – gluconic acid and hydrogen peroxide, which are partially responsible for honey acidity and suppression of bacterial growth. [8]

Adulteration

Honey is sometimes adulterated by the addition of other sugars, syrups, or compounds to change its flavor or viscosity, reduce cost, or increase the fructose content to stave off crystallization. Adulteration of honey has been practiced since ancient times, when honey was sometimes blended with plant syrups such as maple, birch, or sorghum and sold to customers as pure honey. Sometimes crystallized honey was mixed with flour or other fillers, hiding the adulteration from buyers until the honey was liquefied. In modern times the most common adulterant became clear, almost-flavorless corn syrup the adulterated mixture can be very difficult to distinguish from pure honey. [30]

According to the Codex Alimentarius of the United Nations, any product labeled as "honey" or "pure honey" must be a wholly natural product, although labeling laws differ between countries. [31] In the United States, according to the National Honey Board (NHB [32] supervised by the United States Department of Agriculture), [33] [34] "honey stipulates a pure product that does not allow for the addition of any other substance. this includes, but is not limited to, water or other sweeteners". [35]

Isotope ratio mass spectrometry can be used to detect addition of corn syrup and cane sugar by the carbon isotopic signature. Addition of sugars originating from corn or sugar cane (C4 plants, unlike the plants used by bees, and also sugar beet, which are predominantly C3 plants) skews the isotopic ratio of sugars present in honey, [36] but does not influence the isotopic ratio of proteins. In an unadulterated honey, the carbon isotopic ratios of sugars and proteins should match. Levels as low as 7% of addition can be detected. [37]

Worldwide production

Production of natural honey in 2019
Country Production
(tonnes)
China 444,100
Turkey 109,330
Canada 80,345
Argentina 78,927
Iran 75,463
United States 71,179
World 1,852,598
Source: FAOSTAT [38]

In 2019, global production of honey was 1.9 million tonnes, led by China with 24% of the world total (table). [38] Other major producers were Turkey, Canada, Argentina, and Iran. [38]

Over its history as a food, [10] the main uses of honey are in cooking, baking, desserts, as a spread on bread, as an addition to various beverages such as tea, and as a sweetener in some commercial beverages.

Due to its energy density, honey is an important food for virtually all hunter-gatherer cultures in warm climates, with the Hadza people ranking honey as their favorite food. [39]

Fermentation

Possibly the world's oldest fermented beverage, dating from 9,000 years ago, [40] mead ("honey wine") is the alcoholic product made by adding yeast to honey-water must and fermenting it for weeks or months. [41] [42] The yeast Saccharomyces cerevisiae is commonly used in modern mead production. [41] [42]

Mead varieties include drinks called metheglin (with spices or herbs), melomel (with fruit juices, such as grape, specifically called pyment), hippocras (with cinnamon), and sack mead (high concentration of honey), [42] many of which have been developed as commercial products numbering in the hundreds in the United States. [43] Honey is also used to make mead beer, called "braggot". [44]

The physical properties of honey vary, depending on water content, the type of flora used to produce it (pasturage), temperature, and the proportion of the specific sugars it contains. Fresh honey is a supersaturated liquid, containing more sugar than the water can typically dissolve at ambient temperatures. At room temperature, honey is a supercooled liquid, in which the glucose precipitates into solid granules. This forms a semisolid solution of precipitated glucose crystals in a solution of fructose and other ingredients.

The density of honey typically ranges between 1.38 and 1.45 kg/l at 20 °C. [45]

Phase transitions

The melting point of crystallized honey is between 40 and 50 °C (104 and 122 °F), depending on its composition. Below this temperature, honey can be either in a metastable state, meaning that it will not crystallize until a seed crystal is added, or, more often, it is in a "labile" state, being saturated with enough sugars to crystallize spontaneously. [46] The rate of crystallization is affected by many factors, but the primary factor is the ratio of the main sugars: fructose to glucose. Honeys that are supersaturated with a very high percentage of glucose, such as brassica honey, crystallize almost immediately after harvesting, while honeys with a low percentage of glucose, such as chestnut or tupelo honey, do not crystallize. Some types of honey may produce few but very large crystals, while others produce many small crystals. [47]

Crystallization is also affected by water content, because a high percentage of water inhibits crystallization, as does a high dextrin content. Temperature also affects the rate of crystallization, with the fastest growth occurring between 13 and 17 °C (55 and 63 °F). Crystal nuclei (seeds) tend to form more readily if the honey is disturbed, by stirring, shaking, or agitating, rather than if left at rest. However, the nucleation of microscopic seed-crystals is greatest between 5 and 8 °C (41 and 46 °F). Therefore, larger but fewer crystals tend to form at higher temperatures, while smaller but more-numerous crystals usually form at lower temperatures. Below 5 °C, the honey will not crystallize, thus the original texture and flavor can be preserved indefinitely. [47]

Honey is a supercooled liquid when stored below its melting point, as is normal. At very low temperatures, honey does not freeze solid rather its viscosity increases. Like most viscous liquids, the honey becomes thick and sluggish with decreasing temperature. At −20 °C (−4 °F), honey may appear or even feel solid, but it continues to flow at very low rates. Honey has a glass transition between −42 and −51 °C (−44 and −60 °F). Below this temperature, honey enters a glassy state and becomes an amorphous solid (noncrystalline). [48] [49]

Rheology

The viscosity of honey is affected greatly by both temperature and water content. The higher the water percentage, the more easily honey flows. Above its melting point, however, water has little effect on viscosity. Aside from water content, the composition of most types of honey also has little effect on viscosity. At 25 °C (77 °F), honey with 14% water content generally has a viscosity around 400 poise, while a honey containing 20% water has a viscosity around 20 poise. Viscosity increases very slowly with moderate cooling a honey containing 16% water, at 70 °C (158 °F), has a viscosity around 2 poise, while at 30 °C (86 °F), the viscosity is around 70 poise. With further cooling, the increase in viscosity is more rapid, reaching 600 poise at around 14 °C (57 °F). [52] [53] However, while honey is viscous, it has low surface tension of 50–60 mJ/m 2 , making its wettability similar to water, glycerin, or most other liquids. [54] The high viscosity and wettability of honey cause stickiness, which is a time-dependent process in supercooled liquids between the glass-transition temperature (Tg) and the crystalline-melting temperature. [55]

Most types of honey are Newtonian liquids, but a few types have non-Newtonian viscous properties. Honeys from heather or manuka display thixotropic properties. These types of honey enter a gel-like state when motionless, but liquefy when stirred. [56]

Electrical and optical properties

Because honey contains electrolytes, in the form of acids and minerals, it exhibits varying degrees of electrical conductivity. Measurements of the electrical conductivity are used to determine the quality of honey in terms of ash content. [53]

The effect honey has on light is useful for determining the type and quality. Variations in its water content alter its refractive index. Water content can easily be measured with a refractometer. Typically, the refractive index for honey ranges from 1.504 at 13% water content to 1.474 at 25%. Honey also has an effect on polarized light, in that it rotates the polarization plane. The fructose gives a negative rotation, while the glucose gives a positive one. The overall rotation can be used to measure the ratio of the mixture. [53] [29] Honey may vary in color between pale yellow and dark brown, but other bright colors may occasionally be found, depending on the source of the sugar harvested by the bees. [57] Bee colonies that forage on Kudzu (Pueraria montana var. lobata) flowers, for example, produce honey that varies in color from red to purple. [58]

Hygroscopy and fermentation

Honey has the ability to absorb moisture directly from the air, a phenomenon called hygroscopy. The amount of water the honey absorbs is dependent on the relative humidity of the air. Because honey contains yeast, this hygroscopic nature requires that honey be stored in sealed containers to prevent fermentation, which usually begins if the honey's water content rises much above 25%. Honey tends to absorb more water in this manner than the individual sugars allow on their own, which may be due to other ingredients it contains. [29]

Fermentation of honey usually occurs after crystallization, because without the glucose, the liquid portion of the honey primarily consists of a concentrated mixture of fructose, acids, and water, providing the yeast with enough of an increase in the water percentage for growth. Honey that is to be stored at room temperature for long periods of time is often pasteurized, to kill any yeast, by heating it above 70 °C (158 °F). [29]

Thermal characteristics

Like all sugar compounds, honey caramelizes if heated sufficiently, becoming darker in color, and eventually burns. However, honey contains fructose, which caramelizes at lower temperatures than glucose. [59] The temperature at which caramelization begins varies, depending on the composition, but is typically between 70 and 110 °C (158 and 230 °F). Honey also contains acids, which act as catalysts for caramelization. The specific types of acids and their amounts play a primary role in determining the exact temperature. [60] Of these acids, the amino acids, which occur in very small amounts, play an important role in the darkening of honey. The amino acids form darkened compounds called melanoidins, during a Maillard reaction. The Maillard reaction occurs slowly at room temperature, taking from a few to several months to show visible darkening, but speeds up dramatically with increasing temperatures. However, the reaction can also be slowed by storing the honey at colder temperatures. [61]

Unlike many other liquids, honey has very poor thermal conductivity of 0.5 W/(m⋅K) at 13% water content (compared to 401 W/(m⋅K) of copper), taking a long time to reach thermal equilibrium. [62] Due to its high kinematic viscosity honey does not transfer heat through momentum diffusion (convection) but rather through thermal diffusion (more like a solid), so melting crystallized honey can easily result in localized caramelization if the heat source is too hot or not evenly distributed. However, honey takes substantially longer to liquefy when just above the melting point than at elevated temperatures. [53] Melting 20 kg of crystallized honey at 40 °C (104 °F) can take up to 24 hours, while 50 kg may take twice as long. These times can be cut nearly in half by heating at 50 °C (122 °F) however, many of the minor substances in honey can be affected greatly by heating, changing the flavor, aroma, or other properties, so heating is usually done at the lowest temperature and for the shortest time possible. [63]

Acid content and flavor effects

The average pH of honey is 3.9, but can range from 3.4 to 6.1. [64] Honey contains many kinds of acids, both organic and amino. However, the different types and their amounts vary considerably, depending on the type of honey. These acids may be aromatic or aliphatic (nonaromatic). The aliphatic acids contribute greatly to the flavor of honey by interacting with the flavors of other ingredients. [64]

Organic acids comprise most of the acids in honey, accounting for 0.17–1.17% of the mixture, with gluconic acid formed by the actions of glucose oxidase as the most prevalent. [64] Minor amounts of other organic acids are present, consisting of formic, acetic, butyric, citric, lactic, malic, pyroglutamic, propionic, valeric, capronic, palmitic, and succinic, among many others. [64] [65]

Volatile organic compounds

Individual honeys from different plant sources contain over 100 volatile organic compounds (VOCs), which play a primary role in determining honey flavors and aromas. [66] [67] [68] VOCs are carbon-based compounds that readily vaporize into the air, providing aroma, including the scents of flowers, essential oils, or ripening fruit. [66] [68] The typical chemical families of VOCs found in honey include hydrocarbons, aldehydes, alcohols, ketones, esters, acids, benzenes, furans, pyrans, norisoprenoids, and terpenes, among many others and their derivatives. [66] [68] The specific VOCs and their amounts vary considerably between different types of honey obtained by bees foraging on different plant sources. [66] [67] [68] By example, when comparing the mixture of VOCs in different honeys in one review, longan honey had a higher amount of volatiles (48 VOCs), while sunflower honey had the lowest number of volatiles (8 VOCs). [66]

VOCs are primarily introduced into the honey from the nectar, where they are excreted by the flowers imparting individual scents. [66] The specific types and concentrations of certain VOCs can be used to determine the type of flora used to produce monofloral honeys. [66] [68] The specific geography, soil composition and acidity used to grow the flora also have an effect on honey aroma properties, [67] such as a "fruity" or "grassy" aroma from longan honey, or a "waxy" aroma from sunflower honey. [66] Dominant VOCs in one study were linalool oxide, trans-linalool oxide, 2-phenylacetaldehyde, benzyl ethanol, isophorone, and methyl nonanoate. [66]

VOCs can also be introduced from the bodies of the bees, be produced by the enzymatic actions of digestion, or from chemical reactions that occur between different substances within the honey during storage, and therefore may change, increase, or decrease over long periods of time. [66] [67] VOCs may be produced, altered, or greatly affected by temperature and processing. [67] Some VOCs are heat labile, and are destroyed at elevated temperatures, while others can be created during non-enzymatic reactions, such as the Maillard reaction. [68] VOCs are responsible for nearly all of the aroma produced by a honey, which may be described as "sweet", "flowery", "citrus", "almond" or "rancid", among other terms. [66] In addition, VOCs play a large role in determining the specific flavor of the honey, both through the aromas and flavor. [66] VOCs from honeys in different geographic regions can be used as floral markers of those regions, and as markers of the bees that foraged the nectars. [66] [67]

Honey is classified by its floral source, and divisions are made according to the packaging and processing used. Regional honeys are also identified. In the USA, honey is also graded on its color and optical density by USDA standards, graded on the Pfund scale, which ranges from 0 for "water white" honey to more than 114 for "dark amber" honey. [69]

Floral source

Generally, honey is classified by the floral source of the nectar from which it was made. Honeys can be from specific types of flower nectars or can be blended after collection. The pollen in honey is traceable to floral source and therefore region of origin. The rheological and melissopalynological properties of honey can be used to identify the major plant nectar source used in its production. [70]

Blended

Most commercially available honey is a blend [71] of two or more honeys differing in floral source, color, flavor, density, or geographic origin. [72]

Polyfloral

Polyfloral honey, also known as wildflower honey, [73] is derived from the nectar of many types of flowers. [72] [74] The taste may vary from year to year, and the aroma and the flavor can be more or less intense, depending on which flowers are blooming. [72]

Monofloral

Monofloral honey is made primarily from the nectar of one type of flower. Monofloral honeys have distinctive flavors and colors because of differences between their principal nectar sources. [75] To produce monofloral honey, beekeepers keep beehives in an area where the bees have access, as far as possible, to only one type of flower. In practice a small proportion of any monofloral honey will be from other flower types. Typical examples of North American monofloral honeys are clover, orange blossom, sage, tupelo, buckwheat, fireweed, mesquite, sourwood, [76] cherry, and blueberry. Some typical European examples include thyme, thistle, heather, acacia, dandelion, sunflower, lavender, honeysuckle, and varieties from lime and chestnut trees. [ citation needed ] In North Africa (e.g. Egypt), examples include clover, cotton, and citrus (mainly orange blossoms). [ citation needed ] The unique flora of Australia yields a number of distinctive honeys, with some of the most popular being yellow box, blue gum, ironbark, bush mallee, Tasmanian leatherwood, and macadamia.

Honeydew honey

Instead of taking nectar, bees can take honeydew, the sweet secretions of aphids or other plant-sap-sucking insects. Honeydew honey is very dark brown, with a rich fragrance of stewed fruit or fig jam, and is not as sweet as nectar honeys. [75] Germany's Black Forest is a well-known source of honeydew-based honeys, as are some regions in Bulgaria, Tara in Serbia, and Northern California in the United States. In Greece pine honey, a type of honeydew honey, constitutes 60–65% of honey production. [77] Honeydew honey is popular in some areas, but in other areas, beekeepers have difficulty selling honeydew honey, due to its stronger flavor. [78]

The production of honeydew honey has some complications and dangers. This honey has a much larger proportion of indigestibles than light floral honeys, thus causing dysentery to the bees, [79] resulting in the death of colonies in areas with cold winters. Good beekeeping management requires the removal of honeydew prior to winter in colder areas. Bees collecting this resource also have to be fed protein supplements, as honeydew lacks the protein-rich pollen accompaniment gathered from flowers.

Honeydew honey is sometimes called "myelate". [80]

Classification by packaging and processing

Generally, honey is bottled in its familiar liquid form, but it is sold in other forms, and can be subjected to a variety of processing methods.

  • Crystallized honey occurs when some of the glucose content has spontaneously crystallized from solution as the monohydrate. It is also called "granulated honey" or "candied honey". Honey that has crystallized (or is commercially purchased crystallized) can be returned to a liquid state by warming. [81]
  • Pasteurized honey has been heated in a pasteurization process which requires temperatures of 72 °C (161 °F) or higher. Pasteurization destroys yeast cells. It also liquefies any microcrystals in the honey, which delays the onset of visible crystallization. However, excessive heat exposure also results in product deterioration, as it increases the level of hydroxymethylfurfural (HMF) [citation needed] and reduces enzyme (e.g. diastase) activity. Heat also darkens the honey, and affects taste and fragrance. [82]
  • Raw honey is as it exists in the beehive or as obtained by extraction, settling, or straining, without adding heat (although some honey that has been "minimally processed" is often labeled as raw honey). [83] Raw honey contains some pollen and may contain small particles of wax.
  • Strained honey has been passed through a mesh material to remove particulate material [84] (pieces of wax, propolis, other defects) without removing pollen, minerals, or enzymes.
  • Filtered honey of any type has been filtered to the extent that all or most of the fine particles, pollen grains, air bubbles, or other materials normally found in suspension, have been removed. [85] The process typically heats honey to 66–77 °C (150–170 °F) to more easily pass through the filter. [86] Filtered honey is very clear and will not crystallize as quickly, [86] making it preferred by supermarkets. [87] The most common method involves the addition of diatomaceous earth to honey that is heated to 60 °C (140 °F) and passed through filter paper or canvas until a filter cake of diatomaceous earth builds up on the filter. [76]
  • Ultrasonicated honey has been processed by ultrasonication, a nonthermal processing alternative for honey. When honey is exposed to ultrasonication, most of the yeast cells are destroyed. Those cells that survive sonication generally lose their ability to grow, which reduces the rate of honey fermentation substantially. Ultrasonication also eliminates existing crystals and inhibits further crystallization in honey. Ultrasonically aided liquefaction can work at substantially lower temperatures around 35 °C (95 °F) and can reduce liquefaction time to less than 30 seconds. [88]
  • Creamed honey, also called whipped honey, spun honey, churned honey, honey fondant, and, in the UK, set honey, has been processed to control crystallization. Creamed honey contains a large number of small crystals, which prevent the formation of larger crystals that can occur in unprocessed honey. The processing also produces a honey with a smooth, spreadable consistency. [89]
  • Dried honey has the moisture extracted from liquid honey to create completely solid, nonsticky granules. This process may or may not include the use of drying and anticaking agents. [90] Dried honey is used in baked goods, [90] and to garnish desserts. [91]
  • Comb honey is still in the honeybees' wax comb. It is traditionally collected using standard wooden frames in honey supers. The frames are collected and the comb is cut out in chunks before packaging. As an alternative to this labor-intensive method, plastic rings or cartridges can be used that do not require manual cutting of the comb, and speed packaging. Comb honey harvested in the traditional manner is also referred to as "cut-comb honey". [81] : 13 [92]
  • Chunk honey is packed in wide-mouthed containers it consists of one or more pieces of comb honey immersed in extracted liquid honey. [81] : 13
  • Honey decoctions are made from honey or honey byproducts which have been dissolved in water, then reduced (usually by means of boiling). Other ingredients may then be added. (For example, abbamele has added citrus.) The resulting product may be similar to molasses.
  • Baker's honey is outside the normal specification for honey, due to a "foreign" taste or odor, or because it has begun to ferment or has been overheated. It is generally used as an ingredient in food processing. Additional requirements exist for labeling baker's honey, including that it may not be sold labeled simply as "honey". [93]

Grading

Countries have differing standards for grading honey. In the US, honey grading is performed voluntarily based upon USDA standards. USDA offers inspection and grading "as on-line (in-plant) or lot inspection. upon application, on a fee-for-service basis." Honey is graded based upon a number of factors, including water content, flavor and aroma, absence of defects, and clarity. Honey is also classified by color, though it is not a factor in the grading scale. [94] The honey grade scale is:

Grade Soluble solids Flavor and aroma Absence of defects Clarity
A ≥ 81.4% Good—"has a good, normal flavor and aroma for the predominant floral source or, when blended, a good flavor for the blend of floral sources and the honey is free from caramelized flavor or objectionable flavor caused by fermentation, smoke, chemicals, or other causes with the exception of the predominant floral source" Practically free—"contains practically no defects that affect the appearance or edibility of the product" Clear—"may contain air bubbles which do not materially affect the appearance of the product and may contain a trace of pollen grains or other finely divided particles of suspended material which do not affect the appearance of the product"
B ≥ 81.4% Reasonably good—"has a reasonably good, normal flavor and aroma for the predominant floral source or, when blended, a reasonably good flavor for the blend of floral sources and the honey is practically free from caramelized flavor and is free from objectionable flavor caused by fermentation, smoke, chemicals, or other causes with the exception of the predominant floral source" Reasonably free—"may contain defects which do not materially affect the appearance or edibility of the product" Reasonably clear—"may contain air bubbles, pollen grains, or other finely divided particles of suspended material which do not materially affect the appearance of the product"
C ≥ 80.0% Fairly good—"has a fairly good, normal flavor and aroma for the predominant floral source or, when blended, a fairly good flavor for the blend of floral sources and the honey is reasonably free from caramelized flavor and is free from objectionable flavor caused by fermentation, smoke, chemicals, or other causes with the exception of the predominant floral source" Fairly free—"may contain defects which do not seriously affect the appearance or edibility of the product" Fairly clear—"may contain air bubbles, pollen grains, or other finely divided particles of suspended material which do not seriously affect the appearance of the product"
Substandard Fails Grade C Fails Grade C Fails Grade C Fails Grade C

India certifies honey grades based on additional factors, such as the Fiehe's test, and other empirical measurements. [95]

Indicators of quality

High-quality honey can be distinguished by fragrance, taste, and consistency. Ripe, freshly collected, high-quality honey at 20 °C (68 °F) should flow from a knife in a straight stream, without breaking into separate drops. [96] After falling down, the honey should form a bead. The honey, when poured, should form small, temporary layers that disappear fairly quickly, indicating high viscosity. If not, it indicates honey with excessive water content of over 20%, [96] not suitable for long-term preservation. [97]

In jars, fresh honey should appear as a pure, consistent fluid, and should not set in layers. Within a few weeks to a few months of extraction, many varieties of honey crystallize into a cream-colored solid. Some varieties of honey, including tupelo, acacia, and sage, crystallize less regularly. Honey may be heated during bottling at temperatures of 40–49 °C (104–120 °F) to delay or inhibit crystallization. Overheating is indicated by change in enzyme levels, for instance, diastase activity, which can be determined with the Schade or the Phadebas methods. A fluffy film on the surface of the honey (like a white foam), or marble-colored or white-spotted crystallization on a container's sides, is formed by air bubbles trapped during the bottling process.

A 2008 Italian study determined that nuclear magnetic resonance spectroscopy can be used to distinguish between different honey types, and can be used to pinpoint the area where it was produced. Researchers were able to identify differences in acacia and polyfloral honeys by the differing proportions of fructose and sucrose, as well as differing levels of aromatic amino acids phenylalanine and tyrosine. This ability allows greater ease of selecting compatible stocks. [98]


On a cold winter morning, have you ever tried to squeeze some honey out of the honey bear onto your toast? It is pretty tough, huh? Honey is one of those liquids that is very sensitive to temperature. As the temperature goes down, the viscosity, or resistance to flow, goes way up and you can squeeze and squeeze all you want, but very little honey comes out. If you set the honey bear in a pan of warm water for a few minutes and try again, what happens? One little squeeze and honey comes gushing out all over your toast. The viscosity, or resistance to flow, goes way down as the temperature goes up.

As a measure of a liquid's resistance to flow, viscosity can be thought of as friction inside the liquid. If, for example, you try to ride your bike with the hand brakes on (a form of friction), it is difficult to roll the bike forward. The resistance to motion is high. Likewise, in highly viscous liquids (those with high internal friction), the resistance to flow is high.

Viscosity is a very important quality of liquids that scientists, engineers, and even doctors are frequently trying to measure and change. It is difficult, for example, to transport highly viscous crude oil through offshore pipelines, so scientists and engineers use a variety of methods to try and lower the oil's resistance to flow through the pipelines. Likewise, in medicine, doctors try to keep blood viscosity in the correct range. If blood is "too thick," or viscous, a patient can develop blood clots. If blood is "too thin," or lacks viscosity, however, then the patient is at risk for bruising or bleeding events. Blood viscosity, like most things in medicine, has a happy medium.

Volcanologists (people who study volcanoes) have a big interest in viscosity, too. The viscosity of molten rock or magma determines how easily a volcano will erupt, and what shape the lava flows and resulting mountains will take on. A very thin and fluid magma erupts more easily and forms gentle mountain slopes, while a very thick magma erupts explosively and forms a fat lava flow and steep mountain slopes. So, if you see a mountain formed from a volcano, you can estimate the viscosity of the magma that formed it just by looking at the angle of its slope!

Common liquids around your house (thankfully) don't form mountain slopes though, so to measure their viscosities, you have to use some other method. One of the oldest methods is the dropped-sphere method&mdasha glass marble or sphere of some other material is dropped into a column of a liquid. If the liquid is very viscous (imagine cold honey), it will take a long time for the marble to drop to the bottom of the column. Dropping the marble into a less viscous liquid (like water) will take much less time.

Viscosity of a liquid can be calculated from the time elapsed, provided that you know the height of the column and the densities of the sphere and the liquid. Density is a measure of how "compact" something is. It is the ratio of mass to volume, and is a measure of how much matter is packed into a space. Think of a 1-inch cube of bread. Then think of a 1-inch cube of potato. The potato is denser than the bread (there is more "stuff" in the same space). You can calculate density yourself for an object by using a scale to find out the object's mass and then dividing that by the object's volume. You can also look up the densities of many common substances, like glass, stainless steel, water, seawater, oils, etc. in materials tables.

Knowing the time it took to travel through the column of liquid, the height of the column, the density of the sphere, and the density of the liquid, you can then calculate the viscosity of the liquid with the viscosity equation:

  • &mu (the lowercase Greek letter mu, pronounced "mew") is the liquid's viscosity, in newton-seconds per meter squared (Ns/m 2 ).
  • &Delta&rho is the difference in density between the sphere and the liquid, in kilograms per meter cubed (kg/m 3 ). &Delta (the capital Greek letter Delta) means "change" or "difference," and &rho (the lowercase Greek letter rho, pronounced "row") means density.
  • g is the acceleration due to gravity, 9.81 meters per second squared (m/s 2 ).
  • a is the radius of the sphere in meters (m).
  • v is the average velocity, defined as the distance the sphere falls divided by the time it takes to fall, in meters per second (m/s).

Note: Equation 1 depends on certain assumptions, mainly that the ball has reached its terminal velocity and that something called the Reynolds number is very small. You do not need to understand the technical details of these assumptions to do this experiment. The practical result is that Equation 1 is valid for "thick" liquids like molasses and honey, but it will give inaccurate results for "thin" liquids like water and milk. For more details about Equation 1, see the Bibliography.

So, now it's time to race some marbles and see if common liquids in your home are thick or thin!


Beekeeping Questions

I’ve got a Hybrid Flow Hive and when I did an inspection, the comb on the wooden frames tore. What can I do to avoid this?

The Hybrid hive is one where we've got conventional wooden frames that the bees just fill with their own honeycomb on the edge and the Flow Frames in the centre. Now, the question is when she pulled out some of those frames to harvest the honeycomb, or just to do an inspection, the comb tore. Now that's typical if their bees have gone a bit sideways and they've joined combs together. So the way to avoid that, and it's not entirely possible to completely avoid, but the way to avoid that is to get your hive tool down and cut any pieces that are going crossways. And look, it doesn't matter too much. If you rip the honeycomb a bit, if you put it back in, the bees will get in there and fix it up. They're really good at repairing honeycomb when it's torn. So you can either take it away and harvest that honeycomb, or you could just put it back in. The bees will repair that torn comb.

Do you use an entrance reducer when the temperature gets colder (less than 10 degrees)?

So here we don't get too many colder months, where it gets as low as 10 degrees. We do get a little bit in the middle of winter, but still the days heat up warmer than that. And we really don't need to use the entrance reducer so much here. Unless we're moving a hive, or we've got a weak colony that we want to stop robber bees robbing the colony. So they're the two reasons that we would use them here, they're popular in a lot of areas of the world where they do get quite cold temperatures and a lot of slow months. And you might want to keep mice out or wasps out and things like that. So entrance reducers are more common in those colder regions.

Is it normal to find some dead bees at the front of your hive?

It absolutely is. And it's a nice thing to get out really early in the morning before the bees have cleaned the dead bees away. So the undertakers are doing their work in the hive. It's one of the many jobs in a beehive and they will take the dead out. Early in the morning is the time when you'll see what's going on in the hive, and it can be useful to detect early infestations of say the small hive beetle, because you might see a whole lot of larvae that has been ejected before it's ready and you'll see that on the landing board. Whereas later in the day, they would have cleaned that all off.

So it's quite normal if you think about it. A hive like this could build up to potentially 30,000, 50,000 bees. And to maintain that population, if the worker bees are getting worn out and actually dying after four to six weeks, then there's going to have to be quite a big changeover, quite a lot of new bees emerging from their cells to keep up with a population like that. So it's pretty normal for quite a lot of dead bees to be at the front. However, if you see a carpet of dead bees, then something might be amiss. You could have an insecticide issue or something like that.

There is some water and mould in the pest management tray of my Flow Hive 2. Is this normal? (Michigan, USA)

It is pretty normal because it's not actually inside the beehive. The bees don't get to service that area, it's a collection tray underneath. So what happens is debris falls through, some pollen falls through, some water might go through the mesh and then you've got driving rain coming in the entrance. And that can be a perfect climate for a bit of mould, a bit of scum to build up. So just get your hive tool, the one that comes with our jacket kits, and just give it a good clean out. Put some oil in it if you're catching beetles and put it back in. If you're not catching beetles, then you've got a few choices. You can either just clean it out every now and then, and put it back in. Or you could even decide to run it upside down to save from debris collecting in the tray. Or you could remove it altogether if it's in those warmer times and give your beehive a lot of ventilation.

Does honey get thicker the longer you leave it? Or is the viscosity determined by temperature?

The temperature has a big effect on it. Also your bees, at what moisture content they reduce the honey to. So ideally they’ll get it to about 18% or 16% somewhere in there, that'd be a nice thick honey. That'll keep forever on the shelf, provided the lid is on. But if it's up around 20% and above, then depending on how many colony-forming units of yeasts are in your honey, it could then ferment and will likely ferment. So the viscosity is one measure. But I can feel this honey is very warm here now because it has come from the centre of this hive. But it'll be much thicker and slower on the sides of the hive on a cold and rainy day like this.

But yes, keep an eye on the viscosity. If it looks quite liquid, then you can let it cool down and see if it still performs like honey or whether it still feels a bit liquid. It still feels a bit liquid, it’s not the end of the world, it just means you'll need to consume that before fermentation might occur. You can keep it in the fridge, that'll prolong that time. Or you could just go straight into making some nice honey mead. But if you do want to check, there's a thing called a refractometer, which is a device you can put the honey on and it'll tell you the moisture content.

Drone bee

I'm just going to taste some mint and honey. So yummy, a garden delicacy. Check out this drone, right on the window. The drones are a bit bigger than the other bees. They're a bit more Teddy bear shape than a queen bee, which has an elongated abdomen. And just look for the eyes that touch together in the middle. That's the telltale of a drone if you're just starting out. They're good ones to pick up because they don't have stingers. So if you've got kids and things, don't hand them a worker bee, hand them a drone bee to play with. They don't have any stings. It's very dark that one and it looks like it's pretty new to the world. The way it's moving is kind of slow and it's just working things out. If you see that it must have emerged from its cell, it's just giving it sort of wings go as it gets ready to perhaps take its first flight.

I harvested honey today for the first time, and a lot of the bees were hanging around outside for the whole day. Will they go back in at night? Do you think they stayed outside because we harvested?

If you've harvested and you've got a very busy hive like this with a lot of bees in it, they'll need to clear out in order to repair the cells and also to get the humidity in the hive right. They'll actually need to make space in the hive. If you've harvested one frame, you probably won't notice much difference. If you've harvested all your frames, you'll probably find there's a bit of an exodus, especially if it's hot. The bees will get out of the way and allow that work to be done. And if there are any spills to clean up and things like that, they'll need some space to do that.

If you've got a freezing night ahead, it could be a good idea not to harvest all your frames at once, because those bees might end up out the front of the hive during the night. And it could be a bit too cold for them. So it's the same with conventional harvesting. You end up with a lot of bees out the front if you're ripping off the honey boxes and replacing them with stickies and you'll end up with a whole lot of bees out of the hive for some time. They'll just go back in, yes is the short answer.

How long should it take for the bees to fill the brood box?

So it really depends on how strong your colony is and what kind of nectar and pollen sources are available. If you've got a good virile queen, who's ready to lay and a stimulus of the nectar coming in from the flowers, she will then get to work laying eggs and that will really increase the population and it can happen very fast. And typically in the springtime, you'll get that happening quite quickly and your box will fill up really fast, within weeks. But if there’s not a lot of nectar and pollen available, then it could take months and sometimes you'll get a little colony doing not much for a whole season. And then they might do really well the next season. So for that reason, it's a good idea to have more hives than one. So you can kind of benchmark it and work it out. And that way will increase your chances of storing some honey.

It's really interesting, this hive is bringing in honey, but the others around it aren’t. So it's lucky we have this hive because we get to harvest a beautiful amount of honey. So each colour is kind of different and depending on, I guess the genetics is how far they'll fly to get the nectar source and so on. So there's no one answer to that question, but if things align, you've got good genetics, good laying queen, nectar, they'll breed up very quickly. But typically it'll be months before you're putting your honey super on top. It's called the honey super that our box that's used for honey collection.

We have had bees for five months, and we inspected every one to two weeks, they were great bees, very calm. Then we went on holidays for five weeks, but since we returned the bees have become quite aggressive. We put the super on, but even when we smoke them, the bees are getting really cranky. What could have changed?

So it sounds to me like the queen has changed. Where you've got a gentle colony that's beautiful to open up and work with, they're not aggressive and then they change into an aggressive one, what's happened is they've either lost their queen and they don't have one currently. And that can put them into a more aggressive phase. Or what's happened is they've raised a new queen and the old queen has died or been superseded. For whatever reason, the hive has decided that they want to nurture and raise a new one. And that new queen will go and mate with whatever drones are in the area and during that mating will then she'll collect sperm from 30 or maybe even 60 drones. And all of that genetics will go into forming the new temperament of your hive.

So what you need to do to fix that is first ascertain whether you have a laying queen, so you get into your brood box or your brood inspection. And if you do find you have a laying queen, that’s an opportunity to change her to one with more calm genetics. That's if it bothers you, sometimes you've got an aggressive colony that's performing really well, producing really well, it's not really bothering anyone and you can handle it. Then you can leave it like that. But if it is bothering you and you want to get back to those calm genetics, then by all means go about the process of ordering a queen with known genetics. You'll need to take away the old queen and 24 hours or so later, put the new queen into the hive. Which will be in a little queen cage with about five or so escort bees to keep her alive in the post. The bees will chew away the block of candy at the end of her little cage, she'll be released into the hive and a month or so later, you'll have a different temperament in your hive. If that all feels a bit daunting, then get some help. There's plenty of beekeepers around that are really comfortable with doing that kind of work.

I found a lot of black and white pupae in the bottom of the tray and also hanging from the metal grill in the Flow Hive 2. It looks like the bees were pushing them through the grill. Is it too cold to check them now? And could this be chalkbrood?

Okay, black and white pupae, let me think. If anyone's got a good answer to that question, put it in the comments below. Normally the pupae will be white, but I guess they could be black if they're just starting to form their eyes and form their winged parts. So when you see that kind of thing, then something's a little bit amiss. They've gotten a little stressed. Let's say if you've locked them up for a few days, moving or something like that, or even even a day, sometimes they can get stressed and start rejecting the brood. Another reason could be small hive beetle could have laid in some of the brood frames and damaged some of the brood and the bees will eject them. But there could be other reasons.

Chalkbrood looks like little mummies. They look like a little block of chalk. So that's quite easy to tell if it's chalkbrood, which is something you get when you've got that pathogen around. And then you get a damp cold climate in your hive. So if you're unsure, just keep an eye on it. If it still keeps on happening, then you might want to get some help to diagnose what it is.

During the winter, when the sun is out, is it okay to take off the side viewing panels of the super and leave it for a few hours to warm inside the hive? Or do the bees not like direct sunshine in their super? (Melbourne, Australia)

Solar heat the hives? I wouldn't be doing that because the sun can be quite strong. It's okay to take it off for half an hour or so, but I wouldn't leave it off for hours. You don't want a whole lot of direct sunlight coming in through the windows, or the temperature inside your hive actually might get too high. It’s best to just let the bees do their amazing job of air conditioning their hive. They disengage their wing muscles and they vibrate to warm the hive. They collect water and use evaporative cooling to cool the hive. And they're really good at getting the temperature right for their brood. So just let them do it. They're a European honeybee, so they're used to really cold conditions. They’re used to keeping their hive warm, even up to six months in snow. So they shouldn't need any help from solar heating.

I’m a newbie to Flow and have four hives. How many brood boxes should I aim for on each hive?

So it depends a little bit on you as a beekeeper, and you'll find that some beekeepers will really suggest you have to have multiple brood boxes and other beekeepers will go, no, a single brood box is fine. I'm of the opinion that a single brood box is fine, simply because to me, it's easier when you want to go to find a queen or do your brood inspection. There's only one box to look through the frames instead of multiple. And I find in this area, when you put a second brood box, what you get in it is mostly honey stores anyway. And I would rather them store honey in the Flow Frames so we can harvest in this gentle easy way without having to go through the conventional method of harvesting. So the way I like to do it is a single brood box and one or two honey supers on top of that. However, in those colder regions, lots of beekeepers will say it's important to have a couple of brood boxes. So it really is a bit location specific. You might want to find out from your local beekeepers, get more than one opinion before you make up your mind.

I've got the Flow Hive and just got a nuc. It's early winter and I have installed a frame feeder. How long before spring, should I replace it with an empty frame? (Queensland, Australia)

Probably just as you see the bees getting nice and busy. Spring can come a little bit early in this area, so it might actually come in the last month of winter. Keep an eye out for what your bees are doing and what going on. And if they're getting busy and there are flowers flowering etc, a nice early spring, then take away the feeder, they don't need it anymore. A lot of beekeepers will actually stop feeding over the wintertime.

However, in Toowoomba, it doesn't get it doesn't really get so cold there. So you find there will be times in the winter that your bees will be foraging. So you can probably keep on feeding them during the winter if you really wanted to give them a helping hand. The general rule of thumb is feed them prior to winter so that they can get some stores and then leave them alone during that wintertime, and then open them up and check in the spring. So that's what beekeepers in those colder regions generally do. In this more subtropical kind of region, then you could feed them in winter if there was no forage for them. And yes, take it off before the spring. You don't want any honey stores polluted by sugar syrup.

What sort of bees do you keep?

These are Apis mellifera , which is a European honeybee that humans have dragged all around the world with them because they're such incredible pollinators. It's hard to believe, but a hive like this could pollinate 50 million flowers in a day, which is absolutely extraordinary. There is no other insect on the planet that can form a colony and do this amount of pollinating work. Plus they make this extraordinary thing we call honey. So Apis mellifera , the European honeybee is an amazing species. And that's the one generally kept in Flow Hives. In Japan, there's, there's Apis cerana japonica , which is an Asian honeybee and it needs a slightly smaller hive. So we have actually done some trials, modifying the Flow Hive, making them smaller, and they can use the Flow Frames with that other species. There's also the Cape honeybee in South Africa that has also been trialled and has successfully been used to store honey in the Flow Hives. But generally it's mainly for European honeybee.

But if you're asking about what the actual breed is, then within that beekeepers will breed their favourite kind of breeds. And there'll be Italians, Caucasians, Carniolan, etc. And they're very similar and you find that you've got a mix of them in your hive. But breeders will swear that they're better at one thing or another. So the Caucasians for instance, are said to be able to throttle the size of their hive better to the nectar available and therefore last longer through the lean times, and also forage a little bit further. So you hear these things, but typically what happens is you get a bit of a mix because there's genetics from the drones. There might be 30 to 60 fathers and you'll find light bees and dark bees and all sorts in your hive.

Is the Flow Hive suitable for Asian bees?

The Asian honeybee has been successfully trialled. They produce a lot less honey than the European honeybee. However, it's a delicacy in countries like Japan, and you need to provide them a smaller size colony, a smaller size box than this. And you can shorten the Flow Frames they're made to be adaptable to fit that size. And yes, it has been successfully trialled with that Asian honeybee.

Now that it is getting a bit colder, I’ve noticed that the bees are migrating more to the middle of the Flow Frames and are not visible through the windows anymore. They're still really active during the day. Is that normal in winter? (Australia)

It is. What happens is your bees will form a cluster in the centre of the hive and they do that so they can keep nice and warm. They bundle together in those colder times, they disconnect their wing muscles and vibrate, and they keep themselves warm enough to survive. Honey is their fuel. So they will consume the honey in the bottom box. And then they will actually move up to another box if there is one and consume that if they need to as well. So for that reason, you want to remove the excluder before you've got a long winter ahead. And that way your queen might be left behind, below the excluder if that ball moves up into a higher box on your hive.

Does it matter whether you have a second super or a second brood box to get through the cold winter months? (Central USA)

It doesn't matter. If you live in an area where beekeepers are generally advising you need multiple boxes to get through the winter, then you can have a second super or second brood box. Now, some people prefer to take the Flow Frames off for the winter in those colder regions and other people will leave them on. Now, if you've taken your excluder out and left your Flow Frames on your hive for the bees to consume the honey, then you'll need to make sure come springtime, that you shake all the bees down to the bottom box and put your excluder back in place so the queen doesn't start laying in the Flow Frames. Some queens will some queens won't. So if you decide to run without an excluder altogether, then you'll need to find out whether your queen is one that lays in the Flow Frame cells. Getting back to your question of another brood box or another super it's really up to you. If you do another brood box, they will be storing a lot of honey in that, that can be used for getting your bees through the winter.

I have a spot where I'd like to put my hive, but in summer it will be in sun all day. Is it better to have the hive in the sun or the shade?

So here we get some pretty cracking hot days in the summer and these hives don't get any shade. And our bees are fine. Depends exactly how hot it gets, but here we get 40 degrees Celsius days. We get some really hot afternoons and our bees are great at keeping the hive cool. They're amazing at collecting water and doing the air conditioning. So generally bees will be fine in the sun. However, if you can give them a little bit of afternoon shade in those hot summer months, then that will help them out with the air conditioning of the hives. If you have a choice between full shade or full sun, I would go for sun. Pathogens like chalkbrood will take hold in the cold and damp times. And one method of getting rid of chalkbrood is moving your hive into the full sun. So ideally,l shade in those hot afternoons or even shade throughout the summer. But if you can't get that, then full sun is preferable over full shade. But if you can't get that, then still a lot of people are keeping bees in the full shade as well.

How can you tell if the middle frames are properly capped if you can't see them from the side windows?

So you can't a hundred percent know unless you pull them out. But what we've done is designed it with windows here and windows there. And after a while, you'll get a fair idea of whether they're capped or not. If you want to do some learning and you're unsure what's going on, then pull some frames out and have a look. But after a while, the concept is you should be able to look through the windows and make an educated decision on what you're seeing as to when your honey is ready to harvest. Sometimes you can get into a situation where it looks like this all the way across. It looks really nice and full, but your bees are actually in a hungry time and have eaten some of the honey away, directly above the brood nest in the centre of the hive. So that can happen.

And typically in the early springtime here, you'll see that kind of pattern where you can get missing uncapped honey in the centre above the brood nest. But looking through the side windows and looking at this rear window tells a bit of a story of what's going on. And what we're seeing here is a pattern of filling when you've got a whole lot of cells like this, that's a filling pattern. When you've got a really patchy pattern with it all the way full and capped, then missing, then all the way full and capped, then missing kind of randomly on the frames, that's a hungry pattern. So when the bees are a bit hungry, it's not a good idea to harvest. And it's good to wait till you see a filling pattern again, and watch that for a little while. And if that filling pattern has been going good, and you've seen some nice capped honey, then it should be ready to harvest.

I recently took some honeycomb from the brood box to eat and I’ve noticed that since then, the super has dropped drastically in bee numbers. What would cause this? Are they building up the comb in the brood box again? (Brisbane, Australia)

I'm not sure. So if it's a great idea to keep an eye on the bee numbers, it's one of the early warning signs of something going amiss in your hive. So what I do is, I've got about 40 or so hives at home and each day I drive past and I just have a look at the entrances. And if I see that one hive has really not much activity compared to the others, I'll take a mental note to look at that hive. So looking at the entrances at different times of day will tell a bit of a story of what's going on. Also looking into the windows, as you say, keeping an eye on it. And if the bee numbers are dropping, take off the top box and do a brood inspection , just make sure you do have a laying queen. You can get into the situation where your hive has swarmed for instance, and you want to make sure they have actually successfully raised a new queen so they can keep going and make sure she's starting to lay. Or perhaps they're dropping for, for some other reason. And you might need to check for any signs of disease in your brood box. So bee numbers dropping, make sure you stay on top of things like hive beetles as well. Put some oil in that tray at the bottom if you've got the small hive beetle in your area.

I have the Flow Hive Hybrid and it’s my first year. Once they fill the brood box, should I add another brood box for the bees to fill for winter or just use the Flow super next? I’m worried about leaving the Flow super on over the winter times.

I think it’s better to put the super on early, get them used to it. What happens if you go one box and then another box, and then the Flow super on top of that, there'll be a long time before you're collecting any honey in it. You'll probably get a bit impatient. And what you actually want to do is get them started on the Flow Frames first, before you start adding more boxes and that way they'll get in there and cover them all in wax and start the process of storing honey. Once they've done that, then go ahead and add another box if you want to or need to. But your question of the winter coming, that's a bit of a harder one to answer. You might want to ask your local beekeepers how much storage of honey your bees need to survive the winter ahead. And if they do need a lot, then as you say, you might decide to just add a conventional box and let them store in that rather than put your honey collection box or the super it's called on top.

I have 2 Flow Hives, both hives are really strong and until recently had lots of bees in both of the supers. Recently, as winter is approaching there are less bees in the super and they are more in the brood box. If I leave the super on over winter, will it cause any problems? (Adelaide, Australia)

Possibly, it's quite common for beekeepers in the colder areas to take their supers off for winter. Ask your local beekeepers, find out whether they would take off the supers for winter. Typically beekeepers harvesting in a conventional fashion might have multiple boxes and they might just bring it down to a hive size like this, with one brood box and one super, or a couple of brood boxes to survive the wintertime. So it may be the case that it's quite okay to leave it in this configuration with two boxes. What you're really trying to avoid is too much space in the hive for the bees to keep warm. You're just reducing the size of the hive, making it a bit easier for your bees during those cold times. So you could go either way, I think in your area. But getting some advice from local beekeepers would be a good idea.

What part of Australia are you in?

We're here just south of Byron Bay and it's a subtropical region. So we actually get quite good honey flows in the winter. We're in our wintertime here. Now it’s a bit of a cold rainy day and we've noticed the bees are still bringing in honey into some of the hives, but not all of our hives. Down in the valley below you can see macadamias and you can see sugarcane. Beyond that., you can see a lot of paperbarks on the swamp lands that produced quite good honey over the winter.

Do you continue to provide a water sugar mix once the brood box is built out and the super is on?

No. When you feed it's typically because your bees are very hungry. As soon as they show signs of bringing in their own nectar, then you'd take the feed away and let them do it themselves. Sugar is used as a bit of an emergency relief when there are not enough honey stores in your hive. But it's better if they collect their own nectar, that will actually be better for them. Having said that, if your bees are starving, feed them, it's better to feed them sugar than it is to let them starve out.

Should I see eggs and larvae consistently throughout the season? In my last hive inspection, I saw very few larvae or eggs. Could this be an issue with the queen or can this problem be temporary?

So it can be temporary. If you saw very few, it means you saw some, so there are a few reasons why you might get a less virile brood pattern, and one could be your queen is actually getting a bit old and just starting to lay less. Could be the time of year, she could be responding to the reducing amount of nectar. So where you are in the world might help you answer that question as well. They could be downsizing their hive to have less mouths to feed, during the winter ahead. But generally if you've got other hives that are really showing a good brood pattern, a lot of new young bees emerging, a lot of brood in the frames, and you've got one hive that isn't, then you want to keep an eye on that. You might need to replace the queen to one that is going to lay a lot more eggs.

What would you recommend as the best Flow Hive to get started? (UK)

So generally in the colder areas, people go for the larger size hive. I've just said there's a little bit more storage in the hive for that wintertime. So this is our Flow 6, which fits nicely with the 8 frame Langstroth hive size. All boxes vary a little bit, but generally there's two main sizes of what we call the Langstroth hive. So there's eights and tens in the brood box. This is an eight on the bottom, but matches up to a Flow 6. This one here has seven Flow Frames in the top box. It matches up with 10 brood frames.

When we were inventing the hive, we did a lot of math to work out the exact size we wanted that would match both the eights in the tens, the two commonest sizes in the world. So that works quite nicely. And the reason why the Flow Frames are wider than standard brood frames is that when bees make honeycomb away from the brood nest, they'll do really larger size cells and longer cells. And for that reason, we gave them comb sizes that are more suited to honey than brood. And you might find that if you've left the plug out in the inner cover, they'll build a whole lot of comb under the lid. So in the UK, you might choose the larger size, which is called our Flow Frame 7.

There is a rose garden 750 metres away from my hive. Will the bees fly that far to forage on those flowers? (Victoria, Australia)

They will certainly fly that far. In fact, bees are so incredible, they can fly up to 10 kilometres, six miles to get forage and bring it back to the hive. They generally will stay a lot closer, three kilometres, a couple of miles, that's a comfortable foraging distance on a day-to-day basis. But if they're hungry, they will fly far. And if you add up all the bee flight, it could be a couple of laps of our entire world. It's incredible how good they are at flying.

Did you know that bees have great value in the religion of Islam? And there are various miracles that bees can perform.

I have heard amazing things about honey and I'm actually 80 years old. I just look a bit younger because of all the honey I ate.

Do I have to pull out the Flow Frames to inspect them?

Yes, you can. But it's designed so that you can harvest honey like this without going through that process of pulling apart the hive. But certainly for your own education, get in there, check them out, see what's going on, pop the cover. We've got videos showing you just how to do that. Lift the Flow Frames out, just have a look, watch the bees working those cells, covering them all in wax and producing their honey. That's a wonderful thing to do.

What's your favourite flavour of honey?

So my favourite thing is to have multiple flavours of honey, and it's such a joy to be able to share that with guests when they come because it starts an incredible story about bees and their importance to our world. And the enjoyment people get out of tasting all the flavours is wonderful. If I could only get one flavour, then it would probably be the lighter, brighter coloured one. It's probably because we get a little bit less of that here. In the springtime, we get these light, very floral, very upper-palate flavour bursts when you taste the honey. You get that from some of our eucalypt species and you get it from some of our rainforest species in this valley below also.

In the wintertime, we get the darker honeys and at my place we even get honey, that's so dark, even in a small jar, you cannot see through it, it's pretty much black. So it's incredible, the range from almost water clear, right through to completely dark and black. And it's wonderful to taste and look and smell all of those flavours and to see them coming into the Flow Frames. And also to be able to isolate them. I'd really recommend harvesting frame by frame like this, rather than mixing them all in one bucket because you get the joy of this flavour versus what's in this frame over here. And over time, you'll get all of these different, beautiful colours and flavours on the shelf. And that's a beautiful thing to share and taste those flavours from your neighbourhood.

I have just started a garden, and I’m about to start planting vegetables, flowers and an orchard. How long should I wait until I get a Flow Hive?

You don't need to wait till you have planted flowers for your bees because bees forage in up to 10 kilometre radius. So even though you can plant flowers like this, this won't do much for their honey stores. But it will help a lot of the native bee species in really giving them stepping stones across the urban landscape. So we plant flowers to help primarily a lot of the native bee species. It's wonderful to learn about them and to bring them into your garden as well. However, you have to plant quite a lot if you want it to affect your honey stores. And there are people that successfully do that by planting out an acre or so of forage for their bees. And they can really then get those flavours into their hive as well. And people plant medicinal species and so on.

But jump right in there, start your beekeeping journey. One way to start is have a look at TheBeekeeper.org . We've got an online training course, which is also a fundraiser. Have a look at that for some really in-depth training material. Or you might decide just to get your hive, put it together in preparation for getting your bees. I'm also here most weeks to answer questions.

So tune in same time next week. Also let us know what you'd like us to cover, and hopefully we can show you something that's of value. And thank you to all of you that are pitching in and answering questions that people are asking.

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