Factors affecting the quality of honey and simple ways to test its quality.
Which factors affect the quality of honey?
i)Presence of poisonous chemical substances and micro-organisms due to pollution and poor harvesting practices or location. If the environment around the apiary is contaminated with germs or chemicals, these may be passed into honey during collection of nectar. E.g. apiaries close to effluent ponds or where agricultural chemicals are in use. Likewise if the harvesting equipments and containers are not clean and kept in hygenic conditions contamination of honey may occur during harvesting.
ii)Presence of excessive undissolved solid substances eg wax particles due to poor extraction/ filtration methods. If proper filtration is not employed, some solid particle may remain in honey which affect the clarity and consistency of honey. However super fine filtration which removes pollen particles is not recommended.
iii)Lower diastase number and high HMF value due to poor extraction and/or storage conditions. Application of heat during extration destroys enzymes and partially decomposes honey sugars resulting into lower enzyme activity and high HMF values. HMF (hydroxy-methyl furfural) is a result of decomposition of simple sugars in honey. Also storing or transporting honey in hot conditions have the same effect as heating honey.However some floral varieties (eg citrus and clover honeys) naturally produce honey with low diastase values.
iv)Presence of foreign matter due to adulteration or poor harvesting practices eg presence of brood as a result of harvesting unripened honey combs. Some dishonest honey supplies may adulterate honey by adding some substances such as inverted sugars, molasses etc, as a way of increasing volume to cheat customers. Also some beekeepers out inexperience or dishonesty may harvest unripened honeycombs which can introduce brood in honey. This affects honey clarity, flavor and shelflife.
v)High water content due to poor storage and harvesting practices. Water content in honey may increase as a result of keeping it in open containers due to hygroscopy. Shelflife of honey mainly depend on water content; the more the water content, the shorter the shelflife.
In fact it is not easy for a normal person to distinguish between good quality honey and adulterated honey in the market place. However simple methods have been developed to help customers test the quality of honey and buy good honey.
1.Water in glass method:slowly drip honey in glass full of water and watch how the honey flows down.Good honey flows steadily as a small string down to the bottom of glass while adulterated honey scatters and mix with water as shown in the picture below.
2.Match stick: Dip a match stick in honey, then strike it on a match box to light it; if it lights then it is good honey and if it fails then it is low quality honey.
3.Using a spoon drop a little honey on the ground;good honey forms droplets on the soil while adulterated or low quality honey scatters on the soil.
4.Stick or spoon method: Take a little honey with a spoon or dip a stick in a jar full of honey then raise it up to about one feet high, then let the honey flow down until it breaks. Pure honey when flowing down looks like a narrow elastic string whereas impure honey breaks into non-viscous droplets.This may also happen if the amount of water in honey is more than 20%.
5.Mix half a glass of honey with equal amount of spirit (methylated spirit) and stir.If honey is pure then it will sink down to bottom but if impure the two will mix thoroughly to form a milky mixture.
6.Put a little honey on a white piece of paper and oberve the results. Impure honey will penetrate quickly and wet paper while pure honey takes a long time to penetrate to the other side of wet paper.
7.Taste:When honey is overheated it loses its natural flowery aroma and taste; it acquires a burning taste and smells smoke. However it requires an experienced personal to know the difference through tasting.
How is the quality of honey determined?
1.water content:Technically the honey refractometer is used to measure the amount of water contentin honey. With this instrument standard bee honey has water content between 17% to 20% and stingless bee honey between 21% to 26%.
When honey is overheated some of its nutrients (especially enzymes) are partially destroyed thus its quality and efficacy is lowered.The main enzymes in honey are invertase and diastase which breakdown sugars and help digestion. Technically raw honey is tested by measuring the amount of diastase value and HMF present in it. Generally high values of diastase and low values of HMF indicate raw honey (unheated) while low diastase values (less than DN 10) and high values of HMF (more than40mg/kg) indicate low quality- that honey has been overheated/overprocessed. While diastase values are expressed in DN numbers HMF values are expressed in mg/kg. Heat affect both diastase and HMF. While DN number shows the amount of enzymes present in a given sample of honey HMF is a compound that is formed by the breakdown of simple sugars in honey( fructose & glucose) by heat,high value of HMF means more decomposition sugars by heat has occurred in honey.Why is honey heated? Some bee keepers apply heat in the process of extraction of honey from honeycombs due to lack of proper equipments for extraction. Also most of industrial processing of honey involve the use of strong heat and ultra-fine filtration.For example pasteurization of honey to prevent fermentation,crystallization or botulism.High temperatures partially destroy beneficial enzymes and boils off volatile compounds that account for the unique floral aroma of the honey.
How is Honey stored?
Good quality honey is dependent on application of proper harvesting methods as well as good storage; i.e good honey may lose its quality as a result of poor storage. The hygiene and temperature conditions of honey in the bee hive is taken care of by the bees but after harvesting efforts need to be employed to maintain that quality.
a)containers for storing/handling honey should not be used for other purposes and must be clean; if possible only new containers should be used. Used containers tend to interfere with the aroma of honey
b)honey should be kept in closed containers to avoid hygroscopy (honey absorb moisture from the air) which increases its water content.
c)honey should not be kept in hot conditions to avoid destruction of enzyme activity and formation of HMF.Though harmless but increase of HMF indicates that the nutrients in honey have been negatively affected by heat.Preferrably honey should be stored at room temperature (about 250 C)