beeswax, in great detail

 
Physical characteristics of beeswax

Virgin beeswax, immediately after being secreted, elaborated and formed into comb, is white. It becomes darker with use inside the hive as pollen, silk and larval debris are inadvertently incorporated. Rendered, but untreated beeswax comes in varying shades of yellow. Pure white beeswax on the market has always been bleached, sometimes using non-chemical methods such as filtration by diatomaceous earth or long exposure to sunlight, sometimes using chlorine or other chemical agents.

The melting point of beeswax is not constant since the composition varies slightly with its origin. Various pharmacopoeias give a range of 61-660C or more commonly, 62-65 0C. Its relative density at 15 0C is 0.958 - 0.970 g/cm3 and its electrical resistance ranges from 5x1012 to 20x1012 Ohm m (Crane, 1990). Its thermal conductivity coefficient is 2.5 x d10-3 Jcm/sCcm2. The saponification value of beeswax is 85-100 (Smith, 1951).

The composition of beeswax

Pure beeswax from Apis mellifera consists of at least 284 different compounds. Not all have been completely identified but over 111 are volatile (Tulloch, 1980). At least 48 compounds were found to contribute to the aroma of beeswax (Ferber and Nursten, 1977). Quantitatively, the major compounds are saturated and unsaturated monoesters, diesters, saturated and unsaturated hydrocarbons, free acids and hydroxy polyesters. Table 4.1 lists the proportion of compounds as presented by Tulloch (1980).

There are 21 major compounds, each making up more than 1 % of the pure unfractionated wax. Together they account for 56% of the wax. The other 44% of diverse minor compounds probably account for beeswax's characteristic plasticity and low melting point (Tulloch, 1980).


Description


% of fraction

Number of components in fraction

Major

Minor

Hydrocarbons

14

10 (5)

66

Monoesters

35

10 (7)

10

Diesters

14

6 (5)

24

Triesters

3

5

20

Hydroxy monoesters

4

6 (1)

20

Hydroxy polyesters

8

5

20

Acid esters

1

7

20

Acid polyesters

2

5

20

Free acids

12

8 (3)

10

Free alcohols

1

5

?

Unidentified

6

7

?

TOTAL

100

74

> 210

The ratio of ester values to acids, a character used by the various pharmacopoeias to describe pure beeswax is changed significantly by prolonged or excessive heating. At 1000C for 24 hours the ratio of ester to acid is changed beyond the limits set for pure beeswax. Longer heating or higher temperatures lead to greater degradation and loss of hydrocarbons (Tulloch, 1980). These changes also influence the physical characteristics of the wax. Thus, excessive heating during rendering or further processing changes the wax structurally and alters the beneficial characteristics of many of its minor compounds, not only the aromatic and volatile compounds.

Bleaching destroys at least the aromatic compounds of wax. Bleached wax no longer has the pleasant and typical aroma of wax and it can be assumed that it also lacks many of the other minor compounds.

Various plant growth promoting substances, such as myricil alcohol (Weng et al., N-1979), triacontanol (Devakumar et al., 1986), gibberellin GA3 (Shen and Zhao, 1986) and a rape oil steroid (Jiang, 1986) have been detected in and isolated from beeswax. Kurstjens et al., (1990) describe at least 11 proteins in the freshly secreted wax scales of A. mellifera capensis worker bees and 13 proteins in the wax combs of A. m. scutellata and A. m. capensis.

The composition of wax from Asian honeybee species is much simpler and contains fewer compounds in different proportions (Phadke et al., 1969, 1971; Phadke and Nair, 1970, 1973 and Narayana, 1970). Since little is known about which compounds or mixtures cause the beneficial medicinal and dermatological effects of beeswax, no conclusions can be drawn from the composition data alone. Ghedda waxes are used locally in many of the same ways as Apis mellifera wax is used in other parts of the world. Meliponid waxes, which are less like honeybee wax than Ghedda wax, have been used by Amerindians for many of the same purposes, as honeybee waxes (Posey, 1978).

Beeswax is considered safe for human consumption and has been approved as an ingredient in human food in the USA (USA, 1978). It is inert, i.e. it does not interact with the human digestive system at all and passes through the body unaltered. However, substances dissolved or encapsulated in wax are slowly released. This property is exploited in many medicinal preparations. At the same time these properties can create a problem when wax is stored near toxic chemicals and pesticides or after treatment with various drugs inside the hive. Any fat soluble toxins can be absorbed and then released much later when the wax is consumed as food, used in cosmetics or given to bees in the form of foundation sheets.

Several methods of rendering wax are possible and may be adapted to various circumstances. Wax can be separated in solar wax melters, by boiling in water then filtering, or by using steam or boiling water and special presses. If soft water or rain water is not available for these processes, hard water (high calcium content) may be used, but 0.1 % of vinegar should be added to it (Crane, 1990). The different methods are described in further detail in many beekeeping publications, for both small scale, low investment processing and for larger scale operations (Clauss, 1982; Adjare, 1984 and 1990; Coggshall and Morse, 1984; Hepburn, 1986; Gentry, 1988; Graham, 1992 etc).

Wax should never be heated above 85 0C. If wax is heated directly (without water) or above 85 0C discoloration occurs. Therefore wax always needs to be processed in water or in a water bath. Wax should not be processed in unprotected steel, iron or copper containers, since it will discolor from reaction with these metals. Direct exposure of wax to hot steam results in partial saponification.

The residues from wax rendering contain sufficient nutrients to be used as poultry food or be turned into good compost. A Polish study measured a crude protein content of 22.12% When added at 4% to the rations of laying hens instead of green forage meal, the residue maintained all growth and health characteristics and improved egg yolk color (Faruga et al., 1975). With some precautions, the residue can also be included in diets for rearing wax moth larvae (see 8.10.7).

Buying

A buyer should make sure wax has been stored for a few weeks after processing in water, since newly cleaned wax may contain up to 20% by weight of water. Much of this water will be lost during the first few weeks of storage. Unpleasant surprises found inside larger blocks of wax may be rocks or other heavy materials.

Beeswax should have its characteristic yellow color and sweet aroma when bought as rendered beeswax. The grey colored layer at the bottom of inadequately cleaned wax cakes is mostly debris. It should be scraped off and may be reprocessed to extract more wax.

Wax cleaned in a solar wax extractor can sometimes be less aromatic and will be much whiter, almost the pale white color of paraffin wax. The aroma of beeswax can be destroyed by overheating and chemical bleaching. Dark colored beeswax has either been inadequately cleaned or has been processed in unsuitable containers made of iron, copper, brass, nickel, zinc (galvanized steel) or their alloys. The latter discoloration can only be reversed with a special metal binding (chelating) process. White (1966) described using approximately 1.9 g of the sodium salt of ethylene-diamine tetra-acetic acid (EDTA) in a liter of soft (rain) water to process approximately 400 g of wax. The mixture was boiled at 1000C for one hour, stirring continuously in a stainless steel, glass or aluminum container. After cooling, the bottom layer was scraped off while the clean part was re-melted in clean water and cooled.

Adulteration with other waxes is difficult to detect without chemical analyses and physical tests, some of which are described in 4.9.

Storage

Beeswax should only be stored in its rendered, clean form. Before rendering, it will quickly be attacked by wax moths, which are able to destroy large quantities of wax in short periods of time (see Figure 4.6). Clean wax in large blocks is not attacked by wax moths. The honey guide of Africa (Indicator minor) is uniquely adapted to digesting wax with an intestinal flora of Micrococcus cerolyticus and the yeast Candida albicans (Friedman et al., 1957). However, the honey guide rarely consumes or steals large amounts of wax while it may destroy wax foundation sheets.

Storage should be in cool dry places and never in the same room with any kind of pesticide. Wax will slowly crystallize over time and as a consequence become harder, but this process is reversible without any damage, just as with crystallized honey. The white bloom, i.e. dust, that sometimes appears on the outside of a wax cake or candle consists of small wax crystals. When melted or pressed with the rest of the wax it reverts to normal beeswax without any residues or impurities. Wax can be stored for very long periods of time without losing its major characteristics as items from Egyptian graves more than 2000 years old have shown.

Quality control

Beeswax, when sold in solid blocks should always both be clean and have the color and odor characteristics described. Though adulteration is easy (usually with cheap paraffin waxes), its detection is only possible with chemical tests, but it will very likely be detected by any larger buyer long before it reaches an industrial user. Adulteration renders the whole batch useless for most purposes and constitutes a considerable loss to the buyer. Therefore, such practices usually result in a buyer ceasing to buy from the supplier and possibly from the country from which the wax came.

Quality standards for wax are set in most countries according to their pharmacopoeias. A few industries like the Japanese cosmetic industry but also the American Wax Importers and Refiners Association specify their own limits (see ITC, 1978). In addition, for each industrial product in which beeswax is being used, there are other industry standards to be observed. These have to be obtained from the respective industry representations or trade publications. Such standards may vary considerably from country to country and manufacturer to manufacturer.

To detect adulteration, a number of tests may have to be conducted. The simplest is to determine the melting point, by measuring the temperature at which the first liquid wax appears during very slow heating. It should be between 61 and 660C or preferably between 62 and 65 0C. However, values within this range are not a guarantee of purity.

Determining the saponification cloud point is an officially accepted, sensitive method for determining adulteration. The method is limited to detecting quantities greater than 1 % of high melting (80-85 0C) paraffin waxes, or more than 6% of low melting (50-55 0C) paraffins. The test measures the amount of hydrocarbons which saponify (turn into soap) in a specific amount of ethanol and give a clear solution. If the solution becomes clear at or below 65 0C, the wax is probably unadulterated with paraffin. If it is adulterated, the solution will turn clear only at a higher temperature. Some of the details of this test are described by Tulloch (1973) for the American Wax Importers and Refiners Association and in section 4.11.15. The saponification cloud point is not suited to detect adulteration with carnauba wax, but gas liquid chromatography (GLC) can detect the 6% of free C32 alcohol (an alcohol molecule with 32 carbon atoms) contained in Carnauba wax. Beeswax only contains very little (Tulloch, 1980).

Tulloch (1980) also suggests that GLC can be used to detect adulteration of beeswax with as little as 1 % of petroleum hydrocarbons from low melting paraffins, but not for detecting low levels of high melting paraffin waxes.

Pharmacopoeia list ester values from 66 to 82 but most beeswaxes range between 72 and 80. Tulloch (1980) suggests values of 70 to 80 are most typical. Acid values range from 16.8 to 24 and ratios between ester and acid values are fairly stable and narrow, mostly between 3 3 and 4.2. The ratios can change after excessive heating and can exceed 4.2 with heating to 100 0C for only 24 hours, while the ester and acid values might remain within set limits. Ester and acid values in waxes from other Apis species may be significantly different (Ikuta, 1931 and Phadke et al., 1969).

In Africa, adulteration of beeswax with dark and sticky Trigona (Meliponidae) wax has been reported (Smith, 1951). Such wax is of little value in most industrial and beekeeping applications, since the resins are difficult to remove.

For standard testing methods, references can be obtained from Crane (1990), ITC (1978), Apimondia, pharmacopoeias and industry associations.

 

 
 
 

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