Honey is often targeted for adulteration with sugars because of economic gains. Honey is adulterated with simple as well as complex sugars which can be mistaken for natural sucrose–glucose–fructose. One of the methods of adulteration is adding starch-based sugar syrups, high fructose corn syrup, glucose syrup and saccharose syrups produced from beet or canes during or after honey processing. Honey cannot be labelled ‘pure’ if it is adulterated with cheap sweetening materials. Therefore, food testing laboratories are required to detect these sugars.
Honey as a food has a high nutritional value and a unique flavour and that is why the price of natural bee honey is much higher than that of other sweeteners. Samples of honey analysed by Food Testing laboratories can detect honey that has been adulterated with sugar syrups and molasses inverted by acids or enzymes from corn, sugar cane, sugar beet and syrups of natural origin such as maple. Adulteration of pure honey with synthetic honey has also become common in recent years. If honey is marketed with sugar limits exceeding the standard limits then the honey can be rejected for sale.
Honey testing methods
Natural honey has low levels of non-sugar ingredients and consists of glucose and fructose as also sucrose or maltose. According to regulations commercially available “pure” honey cannot contain these sugars in excess of the percentages given for honey standards, which is about 5 to 7 percent of all sugars. Detection of sugar adulteration in honey is difficult because of natural variability, differences in species, maturity, environment, processing methods and storage techniques. Honey testing carried out by food testing laboratories is undertaken using different techniques such as spectroscopic, isotopic, chromatographic and trace element analysis. Stable carbon isotope ratio analysis of honey to detect the undeclared presence of cane or corn sugars is a standard technique that is used globally to detect presence of cane sugar and high fructose corn syrup.
Different measures of sugar in honey
Sugars from tropical plants like sugar cane and corn are produced using a photosynthetic pathway referred to as the C4 pathway. On the other hand nectar collected by bees comes from plants that use a different process of photosynthesis called the C3 pathway. Food testing laboratories measure difference in the ratio of the naturally occurring isotopes in sugars arising from the C3 and C4 pathways. Testing honey through this measurement can help to detect the difference in carbons and presence and identification of C4 sugars show that the honey has been adulterated.
Another test carried out by honey testing laboratories is the protein test. In honey protein is derived from pollen and this pollen is analysed for its carbon ratio. The whole honey is analysed for this test and the difference between the values for whole honey and protein is used to calculate the apparent C4 sugar content. Pollen testing is an important test carried out in only by the best food testing laboratories as most often it is difficult to detect pollen content in honey.