Crystallisation and Adulteration of Honey

Crystallisation

From an article written by MoKhalil Hamdan Apeldoorn, the Netherlands

Honey crystallisation or granulation is a natural phenomenon by which honey turns from a liquid (runny) state to a semi-solid state. Beekeepers refer to this as set honey.

The crystallisation of honey is little understood by the consuming public. Many assume that honey appears crystallized to be an adulterated or unnatural product. That is not so. Actually, the crystallisation process is natural and spontaneous. Most pure raw or unheated honey has a natural tendency to crystallize over time. Crystallisation does not affect the honey except for colour and texture. Crystallized honey is not spoiled and preserves the flavour and quality characteristics of the liquid honey. Some honey users like it in this state since it is easy to spread on bread or toast without dripping off, and the taste is richer.

Remember that honey's crystallisation has no bearing on its quality; it is an attribute of pure and natural honey.

Imported honey is commonly been adulterated. The results of an EU investigation reported in the Guardian on March 26, 2023, stated that 46% of 320 samples tested were suspected of adulteration. All ten samples from the UK were suspect.

In 2024, twenty-five samples from various UK Supermarkets were tested using sophisticated apparatus; 95% were adulterated. Additionally, some Chinese people at a trade fair in Paris admitted that they could sell “honey” in the UK that only contains 10% honey because there is no testing. The UK imports 38,000 tonnes of honey from China annually and blends it with other kinds of honey. So, any honey sold as being the produce of more than one country and sold cheap is likely to have been degraded, usually with sugar.

WikiHow cites these DIY tests that help distinguish fake from pure honey. No one test is indicative:

1. A drop of pure honey on your thumb will stay in one place.

2. A drop of pure honey placed in a glass of water will drop to the bottom and not dissolve.

3. A matchstick dipped in pure honey will still be able to ignite when struck.

4. A drop of pure honey placed on a paper towel will not be absorbed.

5. When mixed with a few drops of vinegar essence, pure honey will not foam up.

6. When heated on a stove top, pure honey will caramelise quickly and not foam up.

7. Pure honey tends to crystallize over time.

The causes of honey crystallization

Honey is a highly concentrated sugar solution. It contains more than 70% sugars and less than 20% water. There is much sugar in honey relative to the water content. This means that the water in honey contains an extra amount of sugar than it could naturally hold. The overabundance of sugar makes honey unstable.

It is natural for honey to crystallize, since it is an over-saturated sugar solution. The two principal sugars in honey are fructose (fruit sugar) and glucose (grape sugar). The content of fructose and glucose in honey varies from one type of honey to the other. Generally, the fructose ranges from 30 to 44% and glucose from 25 to 40%. The balance of these two major sugars is the main reason that leads to the crystallisation of honey, and the relative percentage of each determines whether it crystallizes rapidly or slowly. What crystallizes is the glucose due to its lower solubility. Fructose is more soluble in water than glucose and will remain fluid. When glucose crystallizes, it separates from water and takes the form of tiny crystals. As the crystallisation progresses and more glucose crystallizes, those crystals spread throughout the honey. The solution changes to a stable saturated form, and ultimately, the honey becomes thick or crystallized.

Some kinds of honey crystallize uniformly; some will be partially crystallized and form two layers, with the crystallised layer on the bottom of the jar and a liquid on top. Honeys also vary in the size of the crystals formed. Some form fine crystals, and others large, gritty ones. The more rapid honey crystallizes, the finer the texture will be. Crystallized honey tends to set a lighter/paler colour than when liquid. This is because glucose sugar tends to separate out in dehydrating crystals, and that glucose crystals are naturally pure white. Darker kinds of honey retain a brownish appearance.

How fast will honey crystallize?

Different types of honey will crystallize at different rates. Some honey crystallizes within a few weeks after extraction from the combs, whereas others remain liquid for months or years. The following factors influence the speed of crystallisation:

(i) Nectar source collected by bees (the sugar composition of honey),

(ii) the methods in which honey is handled (processed) and
(iii) the temperature in preservation.

The time it will take the honey to crystallize depends mostly on the ratio of fructose to glucose and the glucose to water ratio. Honey high in glucose sugar, with a low fructose to glucose ratio, will crystallize more rapidly, such as alfalfa, cotton, dandelion, mesquite, mustard, and rape (brassica napus). Honey with a higher fructose to glucose ratio (containing less than 30% glucose) crystallizes quite slowly and can stay liquid for several years without special treatment; for example, Robinia (black locust) and Sage.

The higher the glucose and the lower the water content of honey, the faster the crystallisation. Oppositely, honey with less glucose relative to water is a less saturated glucose solution and is slow to crystallize. Honey with heightened water content often crystallizes unevenly (not as a homogeneous mass) and separates into crystallized and liquid parts.

The speed of honey to crystallize depends not only on its composition, but also on the presence of catalysts, like seed crystals, pollen grains and pieces of beeswax in the honey. These minute particles serve as nuclei for crystallisation. Raw honey (unheated and unfiltered) contains bits of wax, pollen, and propolis and crystallizes faster. Honey that has been processed (e.g. heated and filtered) will remain in its liquid form longer than raw honey due to the elimination of nuclei, which encourage the growth of glucose crystals. Honey prepared for the commercial market is usually heated and filtered. Heating and filtration of the honey dissolve any sugar crystals and remove foreign particles that might be present in it. Therefore, the crystallisation is hindered.

The storage temperature has a big effect. Honey crystallisation is most rapid around 10-15 °C (50–59 °F). At temperatures below 10 °C (50 °F), the crystallisation is slowed down. Low temperature increases the viscosity of honey (honey is thicker when cool), and this retards the formation and diffusion of crystals. Honey resists crystallisation best at higher temperatures of more than 25 C (77 °F). When the temperature is 40 C (104 °F), the crystals dissolve. Temperatures above 40 °C (104 °F) will damage the properties of honey.

Liquefying crystallized honey

Crystallized honey can be brought back to liquid consistency by gently heating it in a hot water bath (Bain Marie) or warming cabinet (box) until the honey re-liquefies. Heating should be applied indirectly, not by direct flame to a container.

The temperature in the beehive is about 35 C (95 °F) and can rise to 40 °C (104 °F) during summer periods when bees are ripening honey. To liquefy honey, it is best to heat it at 35-40 °C (95-104 °F). The temperature should not go beyond 40 °C (104 °F) to avoid overheating. Overheating honey for any period of time will reduce its quality by destroying its enzymes, loss of delicate flavour and aroma and darkening the honey colour. Heating must be done with care if the nutritional value of the honey is not to be spoiled. It is possible to re-liquefy crystallized honey without damaging its quality by the methods described below.

Hot water bath – heat a saucepan filled with enough water to reach the level of honey in the jar to 35-40 °C (95-104 °F), then remove it from the heat or turn off the heat. Take the lid off the honey jar and immerse the jar in the water. Let it stand for about 20–30 minutes. The heat will slowly dissolve the glucose crystals and become liquid again. Stir occasionally to even the heat throughout the honey, as crystallized honey is a poor conductor of heat. Replace the hot water if needed. Remove the jar of honey from the water bath when the honey becomes liquid again.

This works well with honey in glass jars, but not so well with plastic containers. They can warp or melt. If honey is packaged in a plastic container set in warm water, not hot water.

Honey in a plastic bucket can be re-liquefied by transferring or scooping it into glass jars, and using the process above.

Avoiding crystallisation.

• Store honey at room temperature in tightly closed containers. The optimum storage temperature is 21 to 27 °C (70-80 °F).

• Avoid storing honey at cold temperatures of 11 to 18 °C (52-64 °F), which is ideal for crystal formation.

• Don’t store it in the refrigerator. Standard refrigerator temperatures accelerate the process of crystallisation.

• Filter honey through an 80 micron filter or pass it through one or more sheets of fine nylon cloth supported with a wire sieve. This removes any small particles, such as pollen grains, flecks of wax, crystals, and air bubbles, that could initiate crystallisation.

• Heat honey in a double boiler to 40 °C (104 °F) to melt any sugar crystals that may be present and delay crystallisation. Check the honey temperature with a candy thermometer to avoid the risk of overheating.

• Honey packers of supermarket honey in the US heat liquid honey to 63 °C (145 °F) for thirty minutes, or 71 °C (160 °F) for one minute or so (flash heat) and then quickly cool it to minimize heat damage. This temperature kills the yeast cells that cause fermentation and keeps honey from crystallizing on the market self for a long period of time. The resulting honey contains very little of the nutritional value of minimally processed or raw honey, including amino acids, minerals, vitamins, live enzymes, and antioxidants that are considered essential for good health.

• When storing supers of empty combs for winter, it is important to get your supers thoroughly cleaned after the extraction of the honey. Place them back in the hive for the bees to clean the residual honey from the cells and store it in the brood chamber. Extracted combs stored with traces of wet honey can form micro-crystals, causing next year’s honey to crystallize prematurely.

Crystallisation by nectar source

Very Slow

African acacia
Robinia pseudoacaci

Cranberry
Sage (Salvia officinalis)
Tulip poplar

Slow

Bell heather (Calluna cinerea)

Blackberry
Borage (Borago officinails)

Chestnut (Castania sativa)
Eucalyptus
Linden/lime/basswood (Tilia)
Maple (Acre spp.)
Hawthorn (Crataegus spp.)
Rosemary
Thyme (Thymus vulgaris)

Rapid

• Apple, pear, plum and cherry
  Clover (Trifolium)
  Dandelion
  Lavender (Common lavender)

  Phacelia (lacy or tansy phacelia)
  Field bean (Vicia faba)
  Holly (Ilex aquifolium)
  Ivy (Hedera Helix)
  Mustard
  Oilseed rape
  Raspberry
  Sunflower
  Wild thyme (Thymus serpyllum)

Further reading

The influence of the moisture weight ratio and the activity of the invertase enzyme on the crystallisation rate of natural honey E. A. Murashov et ala 2021 - before Putin’s war.