Have you ever wondered about honey, what it is and why it’s like it is? What about quality and honey, what should beekeepers know?
Honey comes from Nectar
Nectar is a solution produced by plants that animals collect for food. Plants have special structures that make this solution usually from water and sap flowing in the plant. Often these are found in flowers and attract animals that pollinate the plant, but that is not always the case, and they can sometimes be found on any parts of the plant above the ground. Nor is nectar always there to facilitate pollination.
The composition of the solution varies, but mostly it’s a solution of sugars in water, with small amounts of minerals and organic molecules. The nectars we are interested in contain something like 10% to 40% carbohydrates, mainly sugars like sucrose, fructose, and glucose. As well as the sugars the plants produce other chemicals that, for example, help the nectar store, make it attractive to a particular animal, or repel animals that might steal it.
Nectar is a very dynamic product. It varies for every type of plant, and for the same type of plant growing in different places. It is presented outside the plant’s tissues, so its properties change with the weather and with time. It is a very expensive product, in terms of energy and raw materials, so it’s highly conserved, even re-absorbed, by the plant. It contains enzymes that gradually change the proportions of sugars in the solution, and these sugars make it hygroscopic.
All sorts of animals use nectar as food, from yeasts and bacteria, to insects and birds. Because nectars have such different properties the relationship between the producing plants and the consuming animals can be very specific, but often are not. For example, the consumer may have special mouth parts that specialise in harvesting liquid of a certain viscosity, or it may rely on a solution that contains lots of amino-acids. These relationships can alter as the secretion of nectar changes over time.
What is honey?
If honey comes from nectar it’s obvious the composition and physical properties of honey originate with nectar, but honey bees alter nectar in two important ways.
As they collect the liquid they add a collection of enzymes, (mostly α-glucosidases, generally referred to as ‘invertase’ or ‘sucrase’) that will split a long sugar into small sugars; each sucrose molecule is split in to two sugars, fructose and glucose. They secrete these enzymes from glands in their head as they imbibe the solution, and ‘swallow’ the mixture into their honey stomach (or ‘crop’). During the intake and expulsion of the nectar it’s likely to be contaminated with pollen grains and spores from the environment. An organ in the crop is able to filter some particulates like this out into the bee’s digestive system where they are digested or excreted.
After they have transported it back to their hive they regurgitate the liquid and then concentrate it by evaporating water. Whereas nectar is mostly water, honey has four to five times as much sugar as water. By splitting most of the sucrose into smaller sugars the ‘bees end up with a warm (about 34oC) fructose solution that has a lot of glucose dissolved in it, and a little sucrose (1-2%). How this solution behaves when it cools depends on the exact mixture of sugars in it, but as a rule some or all the sugars will not remain liquid and the honey will slowly granulate.
The honey will also still contain any of the minerals and organic molecules that were produced in the nectar. The minerals are what gives honey most of its colour, the trace molecules contribute to its flavour, aroma and ‘mouth-feel’. It will now be much ‘thicker’; it has a high viscosity – 200 times that of water, ten times that of an oil. Different densities may have some effect on packaging and container size if sold by weight. Some honeys have such high protein contents they exhibit a property called ‘thixotropy’ and need special handling and packing. As honey it will also absorb water even more quickly that its parent nectar did, which it why ‘bees and beekeepers are careful about exposing it to moist air. And it will contain some (uncertain) quantity of pollen grains and microorganism spores as a result of its natural origin.
So honey is concentrated nectar, but honey is a food, defined in law governed by a principle in an international Codex. The Codex alimentarious defines honey too, and if you’re thinking about honey as a commodity, that’s much more important. To paraphrase what the Codex says, “honey is …an unfermented, sweet substance… produced by honey bees from nectar or secretions from living plants… collected… and transformed in honey combs… without objectionable flavours, aromas, or taints absorbed from foreign matter or during storage… or natural plant toxins in an amount hazardous to health.”
Everything we need to understand about honey quality can be read from the Codex.
The first thing is that it is not fermented. If it’s fermented it’s something else, not honey. What prevents honey from spoiling, and fermenting, is its high sugar concentration. As a result, the amount of water in honey is usually regulated by statute. Above 20% water we know honey is likely to ferment, below 17.0% fermentation is not likely. Between those two points the chance of fermentation depends on the count of yeast spores in the honey. This all assumes the honey is homogeneous – the same throughout.
If honey has begun to crystalise (we call it granulation) clearly it is no longer homogenous. As honey naturally granulates, the possibility of fermentation increases. If we incorporate air into honey, it is no longer homogeneous and the possibility of fermentation increases. If we leave bits of leaf, pollen and dust, and the odd bee’s leg in the honey it’s not homogeneous (and we add to the bacteria/yeast content). Not only will various sorts of foreign material set up concentration gradients that permit fermentation we increase the chance of there being ‘objectionable taints’ and the like in our honey. Particulates in the honey can also ‘seed’ premature crystal formation leading to early granulation, and it’s common to filter out most or all particulates.
The other important part of the Codex is that we should expect honey to be a product of living plants, transformed only by honey bees. It should not contain anything (like chemical pollutants) or be adulterated with products that are not ‘a product of living plants’. It should contain the natural enzymes and biological products that are ‘a product of living plants’, insofar as they are not a hazard to human health. We should not be destroying constituent enzymes by over-heating or processing honey, and in any case, we should be able to tell only honey bees have ‘collected, transformed, and combined’ the nectars to honey. There are many tests in use that can check the integrity of honey, but measuring 5-hydroxymethylfurfural (HMF), one of the main volatile alcohols in any honey, has proved a useful general standard. The compound is produced by sugary solutions at a rate that depends on time and temperature, and the ‘HMF’ quantity has proved to be a good proxy for indicating change in the chemical properties of honey. HMF can tell us whether or to what extent we have ‘transformed’ the honey, and not the ‘bees.
Being true to quality
It is important to adhere to local legislation about trade descriptions, food labelling, and weights and measures. There may be specific regulations that deal with food safety, (in NZ the Tutin regulations are the prime example) or standards that must be met to conform with export regulations and compliance in local or overseas markets. None of these take anything away from the principles in the Codex.
There are also conventions (with varying degrees of ‘authority’) that attempt to define how honey shall be described, especially when trading between countries. For many years honey colour has been described using the ‘Pfund scale’ using a colorimeter, and while there are now more sophisticated spectrophotometric measures the Pfund remains part of the beekeeping vocabulary. Several countries have attempted to standardise the descriptions of the aroma and flavour of honeys using tools like a ‘flavour wheel’ (not New Zealand), and as the interest in ‘varietal’ or ‘gourmet’ honeys has grown these have become widely used to describe and classify the variety of honey available, rather like wine tasting. You can find one you like on the ‘web.
Representing the ‘honesty’ of honey is essential in preparing and describing the product. When preparing honey for consumption and sale seemingly small ‘defects’ create doubt about the provenance and preparation process in the mind of the observer. Are those small bubbles from fermentation or sloppy preparation? Why is there sediment at the bottom of the jar and scum on the top? Worldwide, different consumer groups have different attitudes to filtration, clarity, and shelf-life, some more discerning and selective than others.
It is also important that descriptions, of any kind, are true. Apple blossom pictured on the label of a jar of pasture honey is misleading would not be permitted in some jurisdictions. Putting a sprig of lavender in your lavender honey may not be smart, but putting it in clover honey can be construed as a lie.
As consumers become more discerning your product also characterises how you run your business; “You said it was ‘honey’, not ‘honey with added ‘bee bits’!”. Are the fragments an indication of how roughly you treat your bees, an errant wing an indicator of your insensitive beekeeping? Consumers may regard the possibility of mite treatment residues in the honey you supply as a betrayal. While these details may or may not be part of the regulatory environment, they are part of the ethical framework beekeepers have established over many years. Disregard them at your peril.