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Found in Translation
Sweet and Sour Honey
By: Jay Evans, USDA Beltsville Bee Lab
There are many ways that honey bees improve our diets but honey consumption was an early reason to wrangle this species. The taste for honey persists today around the world, sustaining sideliners, families and large corporations in many parts of the world. It is also widely known to soothe and improve relations with neighbors, in-laws and bosses. With any high-value product, there is a risk of inadvertent or purposeful false advertising.
One honey quality trait that is easy to control is water content. Small-scale beekeepers routinely put their honey crops and relationships at risk by bottling honey that hasn’t been fully processed by bees to a net water percentage under 19%. Watery honey both feels weird and is prone to unintended fermentation. Choosing properly capped frames goes a long way to eliminating this problem. If you live in a humid place like Maryland, there is also some risk that open honey will dehumidify some of the local air, pushing water content back above dangerous levels. Truly dry honey can be achieved by technique and awareness, but if you are curious and want to directly assess the water content of your crop, Hanna Bäckmo gives a nice review of the styles and costs of refractometers used by beekeepers in this magazine (https://www.beeculture.com/refractometer/). Certainly, steady honey producers would benefit from investing in, and calibrating, these things.
A bit out of reach for most of us, but essential for the industry, are lab-based assays aimed at confirming honey purity. The methods used for this continue to improve, putting clumsy or sneaky honey producers on notice. Notably, honey yields can be stretched by a variety of refined or expelled sugars. This might be inadvertent, when syrup fed by beekeepers in the Fall for Winter survival lingers, capped until Spring. There is no easy answer to this, certainly not from me, but step one is to get bees through Winter safely, and then assess any remaining capped stores to see if these stores are bona fide honey or syrup that bees dried down but didn’t gobble up as it came in. Ask a beekeeper near you for help.
Photo by Meggyn Pomerleau on Unsplash
More insidiously, producers or packers might outright add less expensive fillers to their honey, increasing yields but losing some of the magic of honey. The technology used to detect such adulteration is improving, and several techniques are now used by regulators, producers and packers to make sure honey is pure. The International Honey Commission described forensic methods for honey purity nearly 30 years ago and updated these methods in 2009 (https://www.bee-hexagon.net/english/network/publications-by-the-ihc/). The U.S. Food and Drug Administration, keeping honest folks honest across the industry, regularly tests new methods against imported and domestic honey to identify so-called ‘economically motivated adulteration’. Using a well-established technique, Stable Carbon Isotope Ratio Analysis (SCIRA), the FDA recently screened bulk and bottled honey samples from eight countries whose honey is imported into the U.S. (https://www.fda.gov/food/economically-motivated-adulteration-food-fraud/fy2122-sample-collection-and-analysis-imported-honey-economically-motivated-adulteration). This test distinguishes ‘C4’ plant sources (largely grasses and grains) from ‘C3’ sources (all the plants with prettier, bee-visited, nectar-rich flowers). The test simply asks if the unexpected C4-sugars, often from corn syrup or sugar cane, are over-represented in honey. There is some tolerance of these C4 sugars due to bee management or assay imprecision but that level is quite low, maybe 7% by volume. Each country in the FDA screen had at least one suspicious honey batch, but the overall frequency of such batches was 10%, a level roughly similar to a much larger recent study in Europe and indicative that honey, by and large, is as advertised.
There are several newer techniques in play now for the high-stakes race between regulators and those who might diminish the reputation of honey. Dilpreet Singh Brar and colleagues in A comprehensive review on unethical honey: Validation by emerging techniques (Food Control 2023, 145, 109482, https://doi.org/10.1016/j.foodcont.2022.109482) describe nearly 50 ways to test your clover. Within the alphabet soup of available methods, they reveal six chromatographic platforms (basically methods to separate parts of a whole by size, electric charge or affinity to some sort of ‘bait’) with increasing sophistication. These machines should put fear in anyone whose honey is not perfectly sound.
As a geneticist, I am fascinated with so-called environmental DNA (eDNA) screens, whereby a complex soup is scrutinized for the genomes of the diverse organisms floating in it. Many will remember the application of eDNA screens worldwide to identify levels and variants of the SARS-Cov-2 virus in city and town wastewater systems (poor interns!; https://www.nih.gov/news-events/nih-research-matters/tracking-sars-cov-2-variants-wastewater). This same methodology is now widely used to confirm the botanical sources of honey, the genotypes of the bees collecting that honey and the myriad of other organisms from the hive environment. Practically, this method also precisely identifies any honey contaminant with a biological source, from corn syrup to diverse flower sources mixed in accidentally in coveted monofloral honeys. It is also a sensitive assay for honey bee disease agents.
For the past 20 years, genetic analyses of honey from hives have been used to confirm the presence of the bacterium responsible for American Foulbrood, Paenibacillus larvae. Federico Lauro and colleagues in Rapid detection of Paenibacillus larvae from honey and hive samples with a novel nested PCR protocol (International Journal of Food Microbiology 2003, 81, 195-201, https://doi.org/10.1016/S0168-1605(02)00257-X) showed the value of this technique for keeping track of non-symptomatic P. larvae populations. More broadly, Leigh Boardman and others have confirmed that this technique can provide a snapshot of the whole range of microbes found in colonies (Boardman, L., P. Marcelino, J. A., Valentin, R. E., Boncristiani, H., Standley, J. M., & Ellis, J. D. Novel eDNA approaches to monitor Western honey bee (Apis mellifera L.) microbial and arthropod communities. Environmental DNA. 2023; https://doi.org/10.1002/edn3.419). Here, colony-collected honey is analogous to the worker-bee samples now used in many disease surveys. Honey collections have the added value of pointing out long-ago arrivals, providing a sort of fossil record for the plants and other organisms a colony might have come into contact with during the past year. The genetic methods behind these screens are astoundingly sensitive (remember, viruses floating alone in tons of sewer sludge) and honey or hive-based screens have promise for anything from virus outbreaks to the detection of newly invasive mites and other pests. It is incredibly hard to pass through an environment without shedding a little DNA, and a little goes a long way for these sensitive methods.
Economically motivated adulteration is detectable with some effort and that’s a good thing for all of us. Honey screening, especially with the twist of identifying genetic signals from hive organisms, is also becoming a nice tool for scientists keen on monitoring disease, plant sources and the genes of the bees that did all the work.
