Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to, as it is the type of honey collected by beekeepers and consumed by humans. Honey produced by other bees and insects has distinctly different properties.
Honey bees transform nectar into honey by a process of regurgitation and evaporation. They store it as a primary food source in wax honeycombs inside the beehive.
Honey gets its sweetness from the monosaccharides, fructose, and glucose, and has approximately the same relative sweetness as that of granulated sugar. It has attractive chemical properties for baking, and a distinctive flavour that leads some people to prefer it over sugar and other sweeteners. Most microorganisms do not grow in honey because of its low water activity of 0.6. However, honey sometimes contains dormant endospores of the bacterium Clostridium botulinum, which can be dangerous to infants, as the endospores can transform into toxin-producing bacteria in the infant’s immature intestinal tract, leading to illness and even death.
Honey has a long history of human consumption, and is used in various foods and beverages as a sweetener and flavouring. It also has a role in religion and symbolism. Flavours of honey vary based on the nectar source, and various types and grades of honey are available. It is also used in various medicinal traditions to treat ailments. The study of pollens and spores in raw honey can determine floral sources of honey. Bees carry an electrostatic charge whereby they attract other particles in addition to pollen, which become incorporated into their honey; the honey can be analysed by the techniques of melissopalynology in area environmental studies of radioactive particles, dust and particulate pollution.
Hygroscopy and fermentation
Honey has the ability to absorb moisture directly from the air, a phenomenon called hygroscopy. The amount of water the honey will absorb 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 humidity rises much above 25%. Honey will tend to absorb more water in this manner than the individual sugars would allow on their own, which may be due to other ingredients it contains.
Fermentation of honey will usually occur after crystallization because, without the glucose, the liquid portion of the honey primarily consists of a concentrated mixture of the 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.
Like all sugar compounds, honey will caramelize if heated too much, becoming darker in colour and eventually burning. However, honey contains fructose, which caramelizes at lower temperatures than the glucose. Honey also contains acids, which act as catalysts, decreasing the caramelization temperature even more. 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 temperature at which caramelization begins varies, depending on the composition, but is typically between 70°C and 110°C. The Maillard reaction will occur slowly at room temperature, taking from a few to several months to show visible darkening, but will speed-up dramatically with increasing temperatures. However, the reaction can also be slowed by storing the honey at colder temperatures.
Unlike many other liquids, honey has very poor thermal conductivity, taking a long time to reach thermal equilibrium. Melting crystallized honey can easily result in localized caramelization if the heat source is too hot, or if it is not evenly distributed. However, honey will take substantially longer to liquefy when just above the melting point than it will at elevated temperatures. Melting 20 kilograms of crystallized honey, at 40°C, can take up to 24 hours, while 50 kilograms may take twice as long. These times can be cut nearly in half by heating at 50°C. However, many of the minor substances in honey can be affected greatly by heating, changing the flavour, aroma, or other properties, so heating is usually done at the lowest temperature possible for the shortest amount of time.
Indicators of quality
High-quality honey can be distinguished by fragrance, taste, and consistency. Ripe, freshly collected, high-quality honey at 20°C should flow from a knife in a straight stream, without breaking into separate drops. 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 excessive water content (over 20%) of the product. Honey with excessive water content is not suitable for long-term preservation.
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 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 containers sides, is formed by air bubbles trapped during the bottling process.
A 2008 Italian study determined 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.
Classification by packaging and processing
Generally, honey is bottled in its familiar liquid form. However, honey is sold in other forms, and can be subjected to a variety of processing methods.
- Crystallized honey is honey in which some of the glucose content has spontaneously crystallized from solution as the monohydrate. Also called “granulated honey” or “candied honey.” Honey that has crystallized (or commercially purchased crystallized) can be returned to a liquid state by warming.
- Pasteurized honey is honey that has been heated in a pasteurization process which requires temperatures of 72°C 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) and reduces enzyme (e.g. diastase) activity. Heat also affects appearance (darkens the natural honey colour), taste, and fragrance.
- Raw honey is honey 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 labelled as raw honey). Raw honey contains some pollen and may contain small particles of wax. Local raw honey is sought after by allergy sufferers as the pollen impurities are thought to lessen the sensitivity to hay fever.
- Strained honey has been passed through a mesh material to remove particulate material (pieces of wax, propolis, other defects) without removing pollen, minerals or enzymes.
- Filtered honey is honey of any type that 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. The process typically heats honey to 66–77°C to more easily pass through the filter. Filtered honey is very clear and will not crystallize as quickly, making it preferred by the supermarket trade.
- 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 of approximately 35°C and can reduce liquefaction time to less than 30 seconds.
- Creamed honey, also called whipped honey, spun honey, churned honey, candied 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.
- 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. Dried honey is commonly used to garnish desserts.
- Comb honey is honey still in the honeybees’ wax comb. It traditionally is collected by 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 labour 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”. In India, honey is harvested from forests in bee’s natural habitat. It is said that honey will be consumed by the bees on the new moon day, so it is cultivated the day before.
- Chunk honey is packed in widemouth containers consisting of one or more pieces of comb honey immersed in extracted liquid honey.
Honey is a food sweetener and also has applications in medicine and tobacco processing.
Shipment / Storage / Risk factors
Liquid honey is bulked in metal drums internally lacquered to prevent adverse reaction. Leakage, leading to weight loss, results from physical damage to containers and such damage may allow entry of water, which would give rise to fermentation.
Honey proved by test to be affected by excessive heat would be down-graded for industrial use at a low price. Comb honey in domestic packs would suffer leakage by melting was at high temperatures (in excess of 50°C), but leakage by crushing of cartons and contamination of adjacent packs is the more common.
Source: The cargo handbook