2.5.4 Products of honey fermentation

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In many regions honey is or was the only, or the most accessible source of fermentable sugars. In some parts of non-islamic Africa, the traditional manufacture and consumption of honey beer is still very common. The base is crudely pressed or drained honey, often with added brood or pollen. An additional nutrient base is generally provided for the yeasts, which may add characteristic flavours as well (see 2.12.5). Occasionally, other available sugars or sugar sources are added, but always the beverage is consumed before fermentation is finished. Preparation by a skilled brewer (in East Africa most commonly women) can be as fast as 5 to 6 hours. Consumption (most commonly by men) is usually still faster.

In Europe, traditional fermented honey products, some similar to African honey beers, others more refined for longer storage, have largely been abandoned and replaced with grape wines and grain beers. The fundamental problem with mead, the honey wine drinkable only after some months or years of maturation, is that without precise control of the yeasts and other microorganisms growing in the must, final flavours can often be very disappointing. The must of honey water by itself does not contain sufficient yeasts, nor the right kind of yeasts or nutrients to allow rapid fermentation. The yeasts most commonly found in honey (Zygosaccharomyces) grow only in concentrated solutions with more than 50% sugar. Unlike honey beer production, even if sufficient yeast is added at the onset to produce rapid fermentation, the whole process lasts much longer, during which strong flavours derived from other microorganisms can develop. Probably also in order to cover unpleasant flavours, old mead recipes often prescribed the addition of fruits or aromatic herbs. The beverage is then referred to as metheglin.

New microbiological understanding of fermentation processes lead to better controlled working conditions and more reliable production. The result is better control of final flavours. As a consequence, production of meads is becoming more popular again (see 2.12.4). There have been many books and articles published describing various processes and recipes. Among them in French by Guyot (1952), in Spanish: Persano (1987) and in English: Adam (1953), Morse (1964 and 1980), Morse and Steinkraus in Crane (1975), a recently reprinted edition of Gayre (1948) as Gayre and Papazian (1986), Berthold (1988a) and Kime et al., (1991). For those with access to international computer networks, a discussion group of mead producers has been established. Further information can be accessed through any of these many recipes and instructions will certainly help, but only personal experience and lots of patience may produce a tasty mead.

Through refermentation by careful addition of honey or incomplete primary fermentation prior to bottling, a sparkling mead can be produced. Refermentation with selected yeasts can also produce a sherry mead. In Poland, meads with extremely high sugar contents are traditionally produced from musts using equal volumes of honey and water. This "Dwojniak" has to mature for very long periods (5 to 7 years) but the primary fermentation is similar to the one mentioned earlier for medicinal syrups from plant extracts and can be conducted with the honey's own osmophilic yeasts. A must with a honey to water ratio of 1:2 requires only 3 years of aging and is prepared with a special strain of wine yeast (Malaga type). This "Trojniak" is still fairly sweet and is preferably made from cornflower (Centaurea) honey (Morse and Steinkraus, 1975).

Honey vinegar can be produced from mead in the same way as wine vinegar. Unless there is some very special appreciation of this unique flavour, the production however, is hardly feasible economically. Mead can also be used as a base from which distilled alcoholic beverages can be produced. Such production is usually for home consumption only.

Most countries permit the production of alcoholic beverages for personal consumption, but require special licenses for commercial production and sale. Equally, there may be restrictions on the use of certain additives and of course, there are countries in which alcohol production, sale and consumption are not allowed at all. Therefore it is necessary to first inform oneself about the local regulations and proceed from there. A few detailed recipes can be found in the recipe section (2.12.4).

2.5.5 Others

The tobacco industry is estimated to use more than 2000 tons of honey annually to improve and preserve tobacco's aroma and humidity (Nahmias, 1981). Since tobaccos, at least in part, are valued according to the rate at which they dry, the importance of honey for the more valuable tobaccos can easily be understood.

Wax moth larval diets sometimes contain honey to improve survival rates (Eischen and Dietz, 1990). These larvae are raised for scientific experiments and fish bait and could be used as human food as well. Diet descriptions and raising instructions are given in section 8.10.11.

Honey is also mixed in solutions with other substances to attract insects for pollination of some agricultural crops. There is however, no scientific study which shows that such treatment increases pollination significantly.

Nahmias (1981) mentions the use of honey for treating meat packing paper in the USA and coating coffee beans prior to roasting in order to increase the aroma of each product.

The cosmetic industry uses honey as a skin moisturizer, softener and restorer of the skin's own moisturising factors in creams, soaps, shampoos and lipsticks. Because of its stickiness it can however only be employed in small quantities. Further details can be found in Chapter 9.

2.6 Honey harvesting and processing

High colony yields are only possible with well populated colonies in areas with abundant nectariferous flora. The honey needs to be harvested before the bees can consume it for further colony development, but sufficient quantities have to be left to provide for the basic needs of the colony. The different management techniques to provide the above conditions depend on the local conditions and cannot be the subject of this chapter, but are found in regular beekeeping textbooks. However, the different management and harvesting techniques can influence the final quality of the honey (Krell et al., 1988).

The following discussion on honey harvesting and processing is intended for both the honey buyer as well as the producer in order to clarify the necessary precautions to be taken to assure a high quality primary product. Only if the raw material is of good quality can the end product be of good quality.

2.6.1 Colonv management

The exploitation of honeybees by man is basically aimed at the harvest of honey. The most rudimentary and ancient method, still employed in some parts of the world, consists of collecting honey from wild swarms. Usually, no attention is paid to the survival of the robbed colony. Combs with honey, but also with brood and pollen are either consumed directly, without any transformation, or used in the production of fermented drinks. Honey from this kind of harvesting is most frequently mixed with pollen and brood juice and all other parts of the hive. While nutritious, it is not a product that can be included in processing of value added products, other than the production of locally appreciated fermented drinks.

The next step in the technological evolution of beekeeping is the keeping of bees in "traditional" hives, made of any kind of suitable, locally available material: tree trunks, rock caves, bark, straw or other plant materials, mud, dung, clay, cut timber or even special cavities provided in stone or mud walls. Harvest time is when the colony has stored the maximum amount of honey. Different degrees of care as to the survival of the colony, are used during harvest, depending on the type and abundance of the bees and the knowledge of the beekeeper. Sometimes, more refined techniques are employed, such as dividing colonies or moving hives according to nectar flows. Thus production becomes more reliable, still involves little expense, but nevertheless remains relatively low in volume. Honey produced from this type of beekeeping can be of good quality depending on the knowledge and care taken by the beekeeper. Product quality ranges from that of the most negligent honey robber to that of a quality conscious, topbar hive producer.

A further evolutionary step is represented by the use of hives with moveable combs, but without frames or foundation sheets. Examples are the topbar hives of Africa now used worldwide and the antique "anastomo cofini" topbar reversed skep hives of Greece. This type of beekeeping unites low cost materials and traditional practices with some of the advantages of frame hive beekeeping, i.e. the possibility to inspect and manipulate the hive and therefore to progress to a more intensive hive management. Honey is extracted mostly by pressing, sometimes by dripping, but also by melting combs in order to separate wax from honey. This last method is not recommended because the overheating and mixture with old combs spoils the quality of the honey. Pressing (see Figure 2.6 and 2.9) and dripping can produce good quality honeys, but even with good comb selection they still contain large amounts of pollen. This by itself is no problem - on the contrary it is more nutritious - but many markets prefer a clear, non-opaque honey.

The more intensive beekeeping practices of the last century were based on the moveable frame hives and virtually all the honey on the international market still comes from this type of beekeeping. All common management practices are aimed at increasing honey yield, either directly through colony migration, adding honey supers and harvesting, or indirectly, by stimulating early colony growth, swarm control, feeding during off-season and pest and disease control. Higher productivity, when compared to well managed topbar hives however, only results from the reusability of the combs and the possibility of migratory beekeeping due to better comb stability. Centrifugal extraction allows quick processing of large quantities and produces honey with the least amount of contamination by other hive materials. The handling of large quantities allows other processing technologies which foster the production of a uniform product with high control of quality standards.

2.6.2 Unifloral honeys

Unifloral honeys represent a sizeable and well-paid portion of the European honey market. Their production depends on management through site selection and selective harvesting. Increasing consumer knowledge and appreciation of honey is developing a particular market niche for honey identifiable by a characteristic colour and flavour, and originating from one or few sources of flowers (see Figure 2.2).

Honey presses in the foreground and water jacketed settling  tanks in the background at the honey processing centre of Northwestern Bee Products, Kabompo, Zambia, which buys, processes and exports honey and wax from mostly traditional barkhive beekeeping.
Figure 2.6 : Honey presses in the foreground and water jacketed settling tanks in the background at the honey processing centre of Northwestern Bee Products, Kabompo, Zambia, which buys, processes and exports honey and wax from mostly traditional barkhive beekeeping.

Differential pricing sometimes makes the production from rarer floral sources very attractive. Even in some developing countries, honeys from certain areas are preferred, though not always directly for reasons of floral origin, but sometimes for quality, liquidity, colour or simply because it looks and tastes the way the most commonly available honey tastes.

The techniques to produce unifloral honeys are based on the possibility of separating honey of one floral period from earlier and later nectar flows on an economically interesting scale. The most commonly used technique is based on migratory beekeeping. Timing the relocation of apiaries, as well as the placing and removing of supers, is of greatest importance. Care also needs to be taken that honey already present in the colony cannot contaminate the colour or flavour of the unifloral harvest. Even if the production of unifloral honeys is not possible or economically feasible, the organoleptic characteristics of the honey (appearance, colour, flavour and taste) are still the elements that more than anything else contribute to its consumer appeal. It is therefore always a good practice whenever possible to avoid harvests that are not much appreciated, i.e. move bees to other areas or leave bitter or otherwise unfavourable honeys to the bees and harvest only at other times of the year.

2.6.3  Contamination during production

The location of colonies in industrial zones or other areas with considerable air pollution such as cities, can lead to considerable contamination of the various hive products with noxious or toxic chemicals. In Canada, USA, UK and Italy, honeybees were used to monitor environmental pollution, since accumulations of certain metals and other substances could be measured in hive products, mostly in pollen but also in honey (Meyer, 1977; Tong et al., 1979; Bromenshenk et al., 1985 and Accorti, 1992). Agricultural use of toxic chemicals is another common and very likely source of contamination. Crane (1990) gives a list of pesticides found in contaminated honey and the quantities in which they are commonly found. Their overall presence is low in regard to permissable limits in fruits for example, but nevertheless, they are present.

Radioactive contamination throughout Europe after the Chernobyl nuclear reactor incident showed in nectars and honeys for a considerable time (Kaatz, 1986 and Dustmann and von der Ohe, 1988). Since most of the contamination was due to plant uptake of radioactive elements replacing normally occurring minerals, the overall content remained relatively low. Although closer to the accident scene and immediately after the incident, safety limits were exceeded. This was mostly due to short lived iodine isotopes, as for example in Austria (Österreichischer Imkerbund, 1986).

Further contamination may result from dirty water sources and non-floral sugar sources. One very productive location, giving several abundant harvests all year round, was, for example, very close to the centre of Georgetown, Guyana. However, it was also very close to the local soft drink factory which continuously spilled considerable amounts of sugar. Such honey was not truly honey and had a very characteristic taste.

The worldwide exchange and shipping of honeybee colonies and queens has led to the introduction of new honeybee diseases in many parts of the world. Unadapted bees cannot resist the new infections and help from the beekeeper is required. Such help usually involves chemical treatments. If unsafe chemicals are used or even if relatively safe chemicals are applied in exaggerated quantities or at inappropriate times, honey is contaminated. Problems with such contaminations have increased in recent years. Buyers are increasingly alert and test regularly for residues. Another source of contamination is the treatment of combs against wax moth during storage. All available chemical treatments leave residues in the wax and only abundant aeration (ventilation) for at least a couple of weeks can reduce the hazard. Well ventilated storage without chemicals is preferred.

2.6.4 Contamination during harvesting

Many harvesting methods are available to separate bees from their honey. Combs can be taken out one at a time and bees may be removed by shaking and brushing. Whole supers can be cleared of bees with a strong air blower. An inner cover or special board with a one-way bee escape can be placed below the honey super. Up to one deep, or two shallow supers, can thus be cleared in 24 hours, if enough space is available below. This method cannot be recommended if colonies are sitting unprotected in the sun, which might melt the combs in the now unventilated supers. None of these three methods will contaminate the harvested honey.

The use of unpleasant smelling chemicals to drive bees away is a technique preferred by many beekeepers because it is quick and easy. Some of the chemicals are illegal for use in many countries, leave unpleasant flavours and odours, are toxic and are absorbed by wax and honey, e.g. carboxylic acid, benzaldehyde, nitrobenzene and others (Daharu and Sporns, 1984). Careful use of butyric acid, marketed as "Bee-go" in the USA has so far not been proven to produce any contamination, but in general, the use of chemicals during harvesting cannot be recommended.

Excessive use of smoke during harvesting will flavour the honey quickly, no matter which smoker fuel has been selected (see Figure 2.7). Microscopic contamination with soot can also be detected. No chemicals should be included in the smoke. Though unavoidable with some bees, heavy use of smoke can be reduced by selecting more favourable (but perhaps more inconvenient) harvesting times (weather, time of day) and shorter and more frequent harvests. A summary of various production features influencing honey quality is presented in Table 2.9.

Heavy smoking during harvesting will flavour the honey.

Figure 2.7 : Heavy smoking during harvesting will flavour the honey.

2.6.5 Cleanliness

Honey in combs, be it in supers of frame hive beekeeping or in the broken combs from topbar or traditional fixed comb beekeeping, already needs to be regarded as a food product. From a microbiological point of view, mature honey is a very stable product, which is neither altered by, nor, does it permit the multiplication of bacterial or fungal organisms. It can nevertheless be contaminated by either non-biological substances or by potential human pathogens. Every caution and care in hygiene should therefore be taken to prevent any form of contamination.

This general requirement must be taken into account during all processing phases. Already in the comb, contrary to many beekeepers' beliefs, honey is exposed to the danger of contamination, since the surface area of contact with the environment is very large. Contact with humid air (during days between harvesting and extraction), with the soil (supers set on the ground, truck bed, honey house floor or combs and frames dropped on the ground), unprotected transportation on dirt roads or in dirty buckets without a lid during comb harvesting and exposure to insects and other animals, can adversely affect honey quality (see Figure 2.8).

Table 2.9:
Beekeeping methods which may have negative
effects on the quality of the honey

Beekeeping method

Possible damage to honey

Location of hives in densely urbanized or industrialized zones or areas otherwise subjected to strong environmental pollution, including agricultural pesticide use Contamination of honey with noxious or toxic residues, possibly damaging to human health, or with sugars not of nectar or honey dew origin
Inappropriate use of antibiotics and other drugs or chemicals to treat or prevent honeybee diseases or control pests Contamination of honey with the same substances
Use of organic chemicals like naphthalene, ethylene dibromide or paradichlorobenzol for comb protection during storage and treatment against wax moths Contamination of honey with the same substances
Use of chemical repellents during honey harvesting Contamination of honey with the same substances
Inadequate use of smoke by quantity or type of combustion matieral Smoky odour and other flavours of honey and contamination with microscopic soot
Use of old and dark combs and/or brood combs Honey of darker colour, comb odour, higher acidity and faster aging
Use of combs with residual honey from a previous year Honey high in yeasts and possibly faster fermentation; premature crystallization of susceptible liquid honeys; contamination of unifloral honeys
Harvesting of incompletely sealed combs, particularly during the nectar flow Excessive moisture content in honey

The extraction room or space needs to be exceedingly clean as well as the space where the honey supers or combs are stored prior to processing. If processed outside, processing should not be done during a windy or rainy day. All surfaces, hands and containers coming into contact with the honey need to be particularly clean. The need for clean water may influence the site of processing centres or the feasibility of beekeeping in certain areas. In many countries there are explicit rules to which any honey producer has to adhere, as far as minimum facilities and cleanliness in the extracting room are concerned.

Honey comb cropping in traditional or topbar hive beekeeping should only be done in buckets with well sealing  lids. The same type of buckets are necessary for storage of extracted honey.

Figure 2.8 : Honey comb cropping in traditional or topbar hive beekeeping should only be done in buckets with well sealing lids. The same type of buckets are necessary for storage of extracted honey.

Among developing countries, Trinidad and Tobago is an excellent example for such rules and the compliance of beekeepers to these standards (see Annex 2 for contact address).

Containers and processing equipment need to be made of material compatible with this very acidic food. No copper, iron, steel or zinc should be used as they dissolve into the honey and may affect colour and flavour, and might reach toxic levels. If further processed into other products, chemical reactions of the contaminants with other ingredients might cause strange discolorations and off-flavours. Instead, stainless steel, glass and food grade plastic can be recommended. Galvanized steel (zinc) may be used for surfaces which come into contact with honey only for short periods, such as in extractors. Used containers need to be free of any odours since honey will absorb these very quickly. Storage containers made of improper material can be coated completely with beeswax or food grade plastic liners to avoid any direct contact. There is, however, no adequate protection if the containers have been used previously for toxic chemicals.

2.6.6 Processing

Uncapping is the first real step of honey processing. It consists of the removal of the thin wax layer that seals the honey cells. The wax caps can be sliced off with a sharp, thin, long knife or special knives heated by steam or electricity. Large numbers of frames are more rapidly processed with partially or completely automated uncapping machines which cut or chop the wax caps with blades, chains or wires.

In comb harvesting the equivalent step is the comb selection (eliminating pieces of comb with pollen or even brood - something that should already have been done during harvesting) the removal of bees etc. and the subsequent thorough mashing of combs. Processing proceeds further by either letting this wax and honey mixture separate by dripping through a screen (strainer) or by pressing it in special honey presses (see Figure 2.9). Modified centrifugal extractors (see Figure 2.10) can also be used (Krell, 1991).

Honey frame processing proceeds, after uncapping, to centrifugal extraction. Extractors range in size from a manual 2-frame model to motorized units extracting more than 12 deep supers at a time. More commonly, 24 to 72-frame radial extractors are used for commercial enterprises. The smaller units for part-time beekeepers can be made out of recycled materials (see Figure 2.10). Though honey can be extracted faster and more completely at higher temperatures, the combs will become softer and might break. Therefore, extraction temperatures should not exceed 300C.

2.6.7 Purification

The next step is the removal of any impurities such as wax particles, other debris and air bubbles incorporated during extraction. There are two practical techniques: settling and straining. The first simply consists of leaving the honey in a suitably large container, so that impurities can separate according to their specific weight, i.e. air bubbles, wax particles, insect pieces and other organic debris float to the surface while mineral and metallic particles drop to the bottom. The surface scum can be removed carefully, or honey can be drawn off near the bottom for bottling without disturbing either surface scum or bottom sediment. Settling velocity varies with particle size (the smallest settle the slowest), container size and honey viscosity, i.e. moisture content and temperature.

At temperatures of 25-300C settling is generally rather quick and can be completed in a few days. Tanks have to be well covered to avoid excessive contact with air. The process can be accelerated by letting honey flow through special buffer tanks prior to filling into the settling tanks. In these buffer tanks the honey is heated through a water jacket, similar to a water bath and then forced to flow up and down through several compartments in the process of which impurities remain at the surface Such a device works well with medium quantities and once heated like this, the honey can also be filtered more easily.

a)Small, common honey press in Zambia b) Larger honey press used to squeeze honey from cappings in Italy.

Figure 2.9: a) Small, common honey press in Zambia;
b) Larger honey press used to squeeze honey from cappings in Italy.

Subsequent settling frees honey of air and foam and, if containers are big enough, allows some mixing of extractions from various colonies, i.e. blending to achieve a certain degree of uniformity of the end-product. The disadvantage is the cost of the containers for the extra storage lasting several days, which in large operations requires several very large tanks and large amounts of extra space.

Straining can be used instead of, or in addition to, settling. It is more frequently used in larger processing plants, where many tonnes of honey are processed every day and where it is therefore inconvenient and uneconomic to immobilize honey for as long as is required for settling.

Strainers can be simple metallic screens, preferably covered with a fine nylon mesh (fine nylon stockings are the best) or a nylon sack filter submerged in a tall, narrow tank. The sack-like filter can also be made of several layers of increasingly finer metal screens (perforated metal sheets). These filters have the advantage of a large filter surface which can be submerged to avoid any further inclusion of air. The finest mesh size used commonly has holes of 0.1 - 0.2 mm diameter. The temperature, for this kind of straining, must be near 30°C.

Finer filtering is usually only done in association with pasteurization and heating of honey to 77 -78°C (see 2.12.1). It serves the purpose of removing all fine materials, including pollen, in order to delay crystallization for as long as possible. Such filtration requires high pressure filters with diatomaceous earth. Since it requires heating, and particularly because it removes some natural ingredients such as pollen, this honey cannot be sold as table grade honey in EEC countries. Consumers in some countries regard it as inferior in quality, while it is the preferred quality for supermarkets and other large marketing chains which want a product with a long shelf-life in a homogeneous liquid state. 

a)View of top of extractor with basket modified for six shallow super frames or 2 deep super frames. Ideally, the gear and chain assemblage  should have a plate below it to protect the honey from oil or other debris. The whole assembly can be easily removed for cleaning or use of the drum for storage.



A normal tangiential extractor similar to

b)Bottom of wire basket with support for radial extraction, covered with aluminum (or wood) plate for broken comb extraction.
c)A 4-frame (8-shallow) tangential extractor modified for radial 4-frame and broken comb extraction. e)modified for broken comb extraction with solid bottom plate and a finer mesh screen (5-mesh) at the bottom 15-20 cm. e) A large honey press/extractor for separating honey from comb uncappings used in Italy.

Figure 2.10: Manual 4 frame radial (medium size super frames), 4 frame tangential (2 deep and 2 medium size super frames) and comb honey extractor all in one made from construction steel, bicycle parts, 110 litre plastic drum and 5-mesh galvanized screen. This is a beekeeper's design (Mr Beizel, Formosa, Argentina) adopted and modified during an FAO sponsored beekeeping project TCP/ARG/0051.
a) View of top of extractor with basket modified for six shallow super frames or 2 deep super frames. Ideally, the gear and chain assemblage should have a plate below it to protect the honey from oil or other debris. The whole assembly can be easily removed for cleaning or use of the drum for storage.
b) Bottom of wire basket with support for radial extraction, covered with aluminum (or wood) plate for broken comb extraction.
c) A 4-frame (8-shallow) tangential extractor modified for radial 4-frame and broken comb extraction.
d) A normal tangiential extractor similar to
e) modified for broken comb extraction with solid bottom plate and a finer mesh screen (5-mesh) at the bottom 15-20 cm. e) A large honey press/extractor for separating honey from comb uncappings used in Italy.

All the above purification methods can only be applied to liquid honeys. It is therefore preferable to use them immediately after extraction, when honey is still naturally liquid and at the right temperature. In processing plants of large buyers, it is however often necessary to purify honeys that have already crystallized. In this case, the honey has to be melted first without destroying any of its characteristics (see 2.12.1).

Even the small buyer sometimes has to clean purchased honey, since most beekeepers do not process their honey to sufficient standards for inclusion in other products and often not even well enough for bottling for direct retail sale. Here too, it is important to proceed as soon as possible after purchase, before crystallization commences. On a small to medium scale, settling is usually the least expensive and least labour-intensive method, particularly if the honey barrels can be stored for a few days in a warm (30 – 35°C) room. As with larger buyers, additional straining assures that the raw product offers at least a minimum standard of hygiene requirements.

Extracted, cleaned or purified honey is ready to be consumed directly or to be included into other products. But processing technology does not end here Other techniques are employed to prepare a product of uniform, constant and agreeable appearance, or to prevent the only possible storage problem: fermentation.

2.6.8 Moisture content

Moisture content of honey is practically the most important quality parameter, since it affects storage life and processing characteristics Even though moisture can be removed after extraction, only completely ripe honey should be harvested, i.e. combs with more than 75 % of the honey cells sealed. To achieve such results prior to the very end of the nectar flow, the colony has to have sufficient super space for storing incoming and ripening honey. When the average atmospheric humidity is not much above 60%, a moisture content below 18% may be expected in the honey (see Figure 2.5). In more humid climates even sealed cells can contain honey with more than 24% even 28% moisture content (Krell, unpublished, and Crane, 1990, respectively). Combs containing fresh nectar should never be harvested, because it can dilute and spoil the whole harvest - unless of course the purpose of harvesting the honey is making beer.

Post-harvest reduction of moisture content can be achieved by leaving honey supers in warm rooms at 30 to 35 0C and circulating warm air through them. At this time, the surface area of the comb relative to the honey mass is still fairly large and does not require any extra equipment for efficient evaporation. In relatively cool climates the circulation of air heated to 35 0C can reduce moisture content in open honey cells by 1 to 3 %. This is the easiest and cheapest of all post-harvest moisture controls. The relative humidity of the air at 35 C has to be controlled, however. If it is more than 60%, aerial moisture will have to be removed by a dehumidifier. In tropical climates, the air temperature will have to be considerably higher (damaging to honey) or prior dehumidification of the air will be necessary. This requires a small, specially sealed room and a dehumidifier.

Post-extraction moisture removal is slightly more involved (Alfa-Laval, 1988), but small scale methods are available (Maxwell, 1987 and Platt and Ellis, 1985). Krell (1992) described a cheap small scale honey drier, adaptable also for solar heating, in which hot air is conducted over a thin film of honey running on an inclined surface. Large scale solar or semi-solar models have been tried successfully (Paysen, 1987). In industrial plants, vacuum driers are used at less than 45 0C, similar to those for dehydrating fruit juices and other foods, but smaller vacuum driers especially made for honey drying are available for less than US$10,000 (see Figure 2.11). Many other systems have been designed over the years, but honey should require such treatment only under exceptional conditions.

2.6.9 Prevention of fermentation

Fermentation is the only microbiological alteration to which honey is susceptible. Only osmophilic yeasts can grow in the high sugar concentrations, but their presence is ubiquitous in honey, nectar, hive interiors, dust and soils. Their rate of multiplication increases proportionally with increasing water content, up to a certain point. Below 18 % moisture content there is little probability of fermentation, but even at concentrations below 17.1 % the risk of fermentation cannot be completely excluded. This aspect of fermentation depends on factors such as the quantity of yeast and other growing factors - honey temperature and the distribution and availability of water following crystallization.

Appropriate and expensive cold storage (see section 2.7) but above all, careful production techniques, can prevent fermentation. If, after all precautions and care, honey cannot be harvested at less than 18% water content, excessive moisture should be removed (see section 2.6.8). Either one of the previously described methods, if carefully used and if honey has not yet fermented, can prevent fermentation without degrading the honey.

Another method is based on pasteurization and the destruction of the yeasts. The osmophilic yeasts found in honey die after only a few minutes of exposure to temperatures between 60 to 65 0C. If the honey is heated and cooled quickly enough, with special heat exchangers feasible only on an industrial scale, very little damage occurs to the honey. Often these pasteurization treatments have two functions, the prevention of fermentation and the postponement of crystallization (see section 2.12.1).

Relatively small quantities of honeys with high moisture content do not justify complicated and costly pasteurization, or drying. They should be directed towards a market with immediate consumption, for processing into other food items or for fermented drinks (see recipes in section 2.12). Such honey should not be considered for shipping over long distances as containers might explode. Careful heating in a water bath to wax melting temperatures (about 65 0C) and subsequent cooling in a water bath with running water may prolong storage life. For small quantities, this is an acceptable compromise between spoilage by fermentation and some loss of quality by heating. Under most circumstances, however, water baths are overheated and honeys are not properly stirred and cooled down rapidly enough. Pasteurization on a small scale can therefore only be recommended for emergencies and not as a routine procedure as it is used in many places. The pasteurized honey needs to be bottled hot in a clean environment in order to prevent reinfection with omnipresent yeasts.

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