Adulteration of honey with sugar syrup and corn syrup has been a problem for a long time. An unscrupulous beekeeper can feed his colonies these products and extract them like honey, or he can add them later, after extraction. The financial incentive is obvious because syrup is cheap and readily available.
Naturally, importers of honey and large-scale purchasers of honey for manufacturing purposes have always been interested in knowing if the liquid they are paying for is pure, or if it has been “cut” with syrups from non-floral sources.
Cane and corn are C4 plants
It turns out that most plants can be identified as either C3 or C4 plants. Roughly 90% of all plants are C3 and about 5% are C4. The names C3 and C4 come from the first compound produced by the plants during the CO2 fixation stage of photosynthesis.
In a C3 plant, the first compound produced has three carbons, and in a C4 plant, the first compound produced has four carbons. A third type of photosynthesis called CAM is found in about 5% of plants, mostly succulents. Since many of these can switch between CAM and C3, they are sometimes included with the C3 species.
The C4 cycle is an adaptation of plants that evolved in very hot and dry climates. They are able to use CO2 more efficiently and they lose much less water due to transpiration, so they can thrive in sere conditions. Most C4 plants are grasses, including sugar cane, maize, and sorghum, and most are wind-pollinated.
Honey is made from the nectar of flowers
By definition, honey is made from the nectar of flowers. Nectar is secreted by nectaries, which are glands located in flowers, and the secretions are especially designed to attract pollinating insects. Some definitions also include secretions from extra-floral nectaries and the excretions of plant-sucking insects (honeydew) as honey sources.
However, the C4 plants maize (corn) and sugar cane do not have nectaries and are not known for producing honeydew. Sweet liquids pressed from the leaves, stems, or other herbaceous parts of a plant are not considered nectar for the purposes of honey, especially after they are refined by industry.
Isotope profiles can identify C4 syrup
C3 and C4 plants contain different ratios of the stable isotopes carbon-12 and carbon-13. Isotopes are different forms of an element. Each isotope of an element has the same number of protons but differing numbers of neutrons in the nucleus. Since extra neutrons affect the weight, they are easily detected
A carbon-12 atom has 6 neutrons and a carbon-13 atom has 7 neutrons, but they both act like carbon. These isotopes do not decay and are not radioactive, hence they are “stable” as opposed to the unstable type that decay and are radioactive. A carbon isotope we have all heard of is carbon-14, which is a radioactive isotope with a very long half-life of 5730 years. By measuring how much of this isotope remains in a very old object, we can determine its age.
In any case, since these heavy carbon atoms are measurable, it is easy to discover if a sample of honey is adulterated with syrups derived from sugar cane or corn by measuring the ratio of the stable isotopes, 13C/12C.
Sugar beets are C3 plants
However, a problem occurs when syrup is derived from beet sugar. Beets are C3 plants and have the normal ratio of stable isotopes found in most nectar-producing plants. So honey contaminated with sugar beet syrup is not detectable with this method.
As you can see, contamination with syrup is an unresolved problem. Isotope analysis is not readily available to the average consumer, and beet sugar adulteration cannot be found in any case. If you are concerned about the content of your honey, it is best to know your beekeeper. . .and know him well.