Authenticity testing of honey is the best-known example of the need for a weight-of-evidence approach. One analytical test is unlikely to give a definitive answer. Using a panel of different tests, using different techniques and principles, can give an incremental list of suspicions.
The routine use of machine learning for constructing reference databases has enabled the rapid expansion of techniques that – in principle – can discriminate differences between “authentic” and “inauthentic” reference samples, and thus could be added to this weight-of-evidence armoury. Two recent publications are a case in point.
In the first study (purchase required) the authors produced their own reference set by adulterating honey with syrups, then showed that they could be discriminated from authentic honey using Differential Scanning Calorimetry (DSC) (they used graph-based semi-supervised learning to construct the classification model). DSC is based on melting curves, and is an indirect measure of water content. It is a cheap, routine, test widely used in many industries and – as such – would be ideal as the first step in an analytical workflow in order to screen out the most crudely adulterated samples.
This second study (purchase also required) is an example of building much more focussed and granular reference databases to address a highly specific authenticity question. The authors measured carbon-13 ratios in honeys (and in their constituent protein) from 196 authentic honeys sourced from 56 cities in Turkey. This analytical technique is usually used as a marker for exogenous sugar addition, but in this study the authors used the more subtle variations (driven by changes in flora, temperatures and humidities) to build a classification model for regional origin. They were able to cluster the honeys into one of 7 distinct geographical regions of Turkey based upon their carbon-13 ratios.
[thanks to FAN-member Peter Farnell for spotting that the original version of this blog referenced "Differential Scanning Colourimetry" - which would, indeed, have been a novel technique worthy of comment]
