The composition of honey
The composition of honey
[http://www.fao.org/docrep/w0076e/w0076e00.htm#con]
The average composition of American honeys, more or less representative of all honeys, is shown in Table 2.6. Table 2.7 lists the various components identified in honeys from all around the world.
Sugars account for 95 to 99% of honey dry matter. The majority of these are the simple sugars fructose and glucose which represent 85-95% of total sugars. Generally, fructose is more abundant than glucose (see Table 2.6). This predominance of simple sugars and particularly the high percentage of fructose are responsible for most of the physical and nutritional characteristics of honey. Small quantities of other sugars are also present, such as disaccharides (sucrose, maltose and isomaltose) and a few trisaccharides and oligosaccharides. Though quantitatively of minor importance, their presence can provide information about adulteration and the botanical origin of the honey.
Water is quantitatively the second most important component of honey. Its content is critical, since it affects the storage of honey. Only honeys with less than 18% water can be stored with little to no risk of fermentation. The final water content depends on a number of environmental factors during production such as weather and humidity inside the hive, but also on nectar conditions and treatment of honey during extraction and storage. It can be reduced before or after extraction by special techniques (see 2.6.9).
Among the minor constituents organic acids are the most important and of these gluconic acid, which is a by-product of enzymatic digestion of glucose, predominates. The organic acids are responsible for the acidity of honey and contribute largely to its characteristic taste.
Minerals are present in very small quantities, potassium being the most abundant. Dark honeys, particularly honeydew honeys are the richest in minerals.
Other trace elements include nitrogenous compounds among which the enzymes originate from salivary secretions of the worker honeybees. They have an important role in the formation of the honey. Their commercial importance is not related to human nutrition, but to their fragility and uniqueness. Thus their reduction or absence in adulterated, overheated or excessively stored honeys serves as an indicator of freshness. The main enzymes in honey are invertase (saccharase) diastase (amylase) and glucose oxidase.
Traces of other proteins, enzymes or amino acids as well as water soluble vitamins are thought to result from pollen contamination in honey.
Virtually absent in newly produced honey, hydroxvmethylfurfural (HMF) is a byproduct of fructose decay, formed during storage or during heating. Thus, its presence is considered the main indicator of honey deterioration.
Even though some of the substances responsible for honey colour and flavour have been identified (see Table 2.7) the majority are still unknown. It is more than likely that honeys from different botanical origins contain different aromatic and other substances which contribute to the specific colours and flavours and thus allow to distinguish one honey from another. Similarly, it is very likely that, depending on their botanical origin, honeys contain traces of pharmacologically active substances. Some of them have been identified, such as those responsible for the toxicity of certain honeys (see also section 2.9), but for the majority of possible substances, scientific verification requires further studies.
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