Honey is what bees make from nectar in order that it will keep; as such it contains what is present in the nectar minus some water. In fact it is much more complicated than that.
Honey is a complex mixture of:
- vitamins and minerals
Approximately 17-20% of honey is water. One of the most important steps in the process is to reduce the water content to below about 20% because it has the effect of making honey indigestible to micro-organisms.
The amount of water the bees can remove depends on:
- the amount or water present in a nectar in the first place;
- the weather;
- the strength of the colony.
The amount of water in a nectar varies with the species of plant and with the weather. For instance – dandelion nectar has a higher sugar content than that of apple which produces a nectar ‘runny’ by comparison.
Superimposed on this is the weather effect. Many flowers tend to point their faces to the sun; this makes them very conspicuous to insects but if it rains then the flower fills with water and the nectar is diluted.
When ripening honey, bees fan at the entrance to pull air through the hive and over the honey to evaporate water from its surface. The warmer and drier the air, the faster the ripening. The amount of air passing over the honey would also speed evaporation and this last is related to the numbers of bees available for fanning. So if the weather is cold and wet and/or colony strength is down then the job is much more difficult and the honey may contain more water than is desirable.
So far, honey contains what was in the nectar and minus a quantity of water.
Of the solids in honey, that is if all the water was to be removed, 95-99.9% is sugar of one sort or another, from the simple to the complex. To understand the complexity, and the simplicity, of sugars and the actions of enzymes it is useful to know a little about carbohydrate chemistry.
2.1. Carbohydrate chemistry
Simple sugars are called monosaccharides. There are very many different species of monosaccharides but what they all have in common is that they are built from a number of carbohydrate sub-units. The basic formula of a carbohydrate is CH2O or H-C-OH. Each molecule of carbohydrate may be thought of as one of the vertebrae which, linked together, make up the spine of a simple sugar and to which, other chemical appendages may, or may not be attached.
Monosaccharides can have a spine of three, four, five, six or seven individual carbohydrates and are known as triose, tetrose, pentose, hexose or heptose monosaccarides respectively. Glucose and fructose are hexose monosaccharides and both are very common in honey.
In Figure 1 below, each C represents a Carbon atom, H is a Hydrogen atom and O is an Oxygen atom. The black lines between them represent the bonds holding the individual atoms together as a molecule. It is important to understand that the atoms illustrated here are not welded permanently into place – it is more as if they are held together by forces similar to magnetism.
Figure 1. Carbohydrate skeletons of 4 monocaccharides.
There are two ways in which each of the above molecules can assemble so that two forms of each exist which are essentially the mirror image of each other – rather like a pair of gloves and they are known as L and D forms. D is for ‘dexter’ which is Latin for right, L is for ‘læve’, Latin for left – although these refer to the direction in which they rotate polarised light and not their handedness.
Sugar molecules, such as those above, in a solution such as in honey, tend to curl up into rings with an oxygen atom forming the clasp so to speak. There are two ways they can do this too, and they are known as a or bconfigurations (see fig 2 below). A solution of pure glucose will contain equal quantities of a & b.
Figure 2 a and b-D-glucose.
There are many ways the different forms of the various monosaccharides can link up but a molecule made of two linked monosaccharides is always termed a disaccharide. Example of disaccharides would be
- sucrose which is made of a-D-glucose and b-D-fructose (see fig 3 below);
- maltose which is made up of two a-D-glucose molecules.