Advances in isotopic analysis for food authenticity testing

Adulteration of food and beverages is an increasing global problem and new fraud cases are frequently reported. This is, for example, evident from the large number of fraud cases revealed in the yearly Europol/Interpol operations (see, eg, Operation Opson IVd2014/2015). Fraud and adulteration can be related to the geographical or vintage origin (wine), the agricultural production method (eg, “conventional” or “organic,” “free-range” or “barn-raised”), the processing method, or cases in which products have been diluted (watered) or in which chemical food components have been substituted by cheaper imitations (eg, undeclared sugar or acid addition). Consequently, consumers are becoming increasingly aware of food quality and safety and demand documentation of the authenticity of food products. The request for analytical methods that can correctly verify the authenticity of food products is therefore greater than ever. Stable isotope ratio analysis (SIRA) represents one of the most well-established and acknowledged methods for authenticity testing; the major advantage of this methodology is its ability to differentiate substances that are chemically identical. Today, SIRA is, for example, routinely used for verifying the authenticity of wine, fruit juices, olive oil, honey, etc (Drivelos and Georgiou, 2012; Roßmann, 2013; Camin et al., 2015b). In this section, we will give a short theoretical background to stable isotope analysis including the major fractionation processes that make isotopic signatures suitable for authenticity testing.