Some important indicators for honey ﬁt for human consumption include crucial parameters that are tested by Rwanda Bureau Standards (RBS) laboratories with intention to not only ensure honey quality for trade but help honey processors improve that sector.
Honey is a sweet food made by bees using nectar from ﬂowers. The variety produced by honey bees (the genus Apis) is the one most commonly referenced. Honey that is not produced by bees should have distinctly different properties.
Ally Clair Harerimana from Inorganic Chemistry Section at RBS says, some people prefer honey over sugar and other sweeteners due to its attractive chemical properties for baking, and its distinctive ﬂavor.
Honey is generally made by bees’ transformation results by a process of regurgitation and evaporation. Honey gets its sweetness from the monosaccharides, fructose, and glucose, and has approximately the same relative sweetness as that of granulated sugar.
PHYSICAL AND CHEMICAL PROPERTIES
Honey is denser than water with a density of about 1.37. The physical properties of honey vary depending on water content, the type of ﬂora used to produce it (pasturage), temperature, and the proportion of speciﬁc sugars it contains.
Fresh honey is a supersaturated liquid, containing more sugar than the water can typically dissolve at ambient temperatures. At room temperature, honey is a super cooled liquid. This forms a semisolid solution of precipitated sugars in a solution of sugars and other ingredients because the glucose precipitates into solid granules.
Like all sugar compounds, honey will caramelize if heated too much, becoming darker in color and eventually burning. The pH of honey is between 3.4 and 6.1. It contains fructose, which caramelizes at lower temperatures than the glucose.
Honey also contains acids, which act as catalysts and interacting with the ﬂavors, adding the aroma and taste.
Those acids are Gluconic acid which is the most prevalent; formic, acetic, butyric, citric, lactic, malic, pyroglutamic, propionic, valeric, capronic, palmitic, and succinic, among many others.Honey is a mixture of sugars and other compounds.
With respect to carbohydrates, honey is mainly fructose (about 38.5%) and glucose (about 31.0%) making it similar to the synthetically produced inverted sugar syrup, which is approximately 48% fructose, 47% glucose, and 5% sucrose.
Honey’s remaining carbohydrates include maltose, sucrose, and other complex carbohydrates.
Honey also contains tiny amounts of several compounds thought to function as antioxidants, including chrysin, pinobanksin, vitamin C, catalase, and pinocembrin.Addition of sugars originating from corn or sugar cane/commercial sugar in honey can be detected by using Fiehe’s test.
“As with all nutritive sweeteners, honey is mostly sugars and contains only trace amounts of vitamins or minerals,” Harerimana says.
High-quality honey can be distinguished by fragrance, taste, and consistency. Ripe, freshly collected, high-quality honey at 20 °C should ﬂow from a knife in a straight stream, without breaking into separate drops. After falling down, the honey should form a bead.
The honey, when poured, should form small, temporary layers that disappear fairly quickly, indicating high viscosity. If not, it indicates excessive water or moisture content (over 20%) of the product. Honey with excessive water content is not suitable for long-term preservation.
However, this physical appearance examination is not enough to conclude on the quality of honey being good or not. Apart from these physical appearances points, RBS laboratories carry out honey test analysis to ensure the quality and its ﬁtness for consumption. Those parameters include Relative Density, Moisture Content, Indicators of Honey QualityHydroxymethylfurfuraldehyde(HMF), Fiehe’s Test, Total Ash (amount of minerals content), Heavy Metals, Sucrose, Total Carbohydrates, Glucose and Fructose Content, Total Solids, Total Water Insoluble Solids and Acidity.
ORIGIN OF TOXIC CHEMICALS IN HONEY
Various synthetic chemicals, such as insecticides and fertilizers, as well as a variety of naturally occurring
chemicals from plants can intoxicate honey. This intoxication can also result from exposure to ethanol from fermented nectar, ripe fruits, and manmade and natural chemicals in the environment.
The honey produced by bees from these toxic nectars can be poisonous if consumed by humans. HMF (HydroxyMethylFurfuraldehyde) is a dangerous and carcinogenic compound which may be present in
honey. It is used as an indicator of heat and storage changes in honey
THE FOLLOWING REACTIONS CHAIN SHOWS HOW HMF IS FORMED:
1. Fructopyranose 2. Fructofuranose 3. Fructose 4. Dehydration stage of Fructose 5. HMF
In fact, HMF is formed by the breakdown of fructose in the presence of an acid.
Heat increases the speed of this reaction. The increase in speed is exponential with increasing heat.
HMF occurs naturally in most honeys and usually increases with the age and heat treatment of honey.
HMF’s occurrence and accumulation in honey is variable depending on honey type.
HMF is used as an indicator of honey adulteration with invert syrups (syrups of glucose and fructose). Sugar cane (sucrose) is “inverted” by heating with a food acid, and this process creates HMF.
CASE OF PASTEURIZED HONEY
Honey is heated in a pasteurization process in order to kill or destroy yeast spores/cells which requires temperatures of 161 °F (72 °C) or higher. It also liqueﬁes any microcrystals in the honey, which delays the onset of visible crystallization. However, excessive heat exposure also results in product deterioration, as it increases the level of hydroxymethylfurfural (HMF) and reduces enzyme (e.g. diastase) activity. Heat also affects appearance (darkens the natural honey color), taste, and fragrance.