NIR spectroscopy coupled with chemometrics to discriminate between fresh and thawed cephalopods

Food fraud is a widespread problem, which has potentially heavy and wide impacts on the consumers’ safety and health, as it affects almost any type of food commodity that is sold on the market. Illegal practices such as product mislabelling and counterfeiting are under any circumstances a violation of the law but may be very difficult to detect. Starting from these premises, we carried out a study aimed at investigating a specific type of food fraud: the sale of frozen-thawed cephalopods mislabelled as fresh, and therefore more expensive, products. The differences between fresh and thawed cephalopods were investigated, using three different NIR instruments to collect the data, followed by chemometric modelling to build classification models. Fifty fresh cephalopods specimens of both cuttlefish (Sepia officinalis) and musky octopus (Eledone spp.) were collected directly at a food distribution warehouse and immediately analysed at refrigeration temperature (~5°C). Then, the specimens were kept frozen at –20°C for at least 48 hours and eventually thawed and analysed once again. Spectral data were acquired by measuring the same specimens using three different NIR spectrometers: one portable low-cost instrument (SCiO by Consumer Physics), one portable medium-high-cost instrument (MicroNIR by Viavi) and one benchtop instrument (MPA by Bruker). From the output of each instrument, one classification model was built. All models showed very good performances, allowing discriminating between fresh and thawed samples with high accuracy. More specifically, the obtained accuracy values were, respectively: 82.3–94.1% for cuttlefish, 91.2–97.1% for musky octopus and 86.8–95.6% for the global model (i.e., a model combining the two cephalopods’ species). To date, there is no other classification method (not even histological) able to provide performances comparable to this spectroscopic approach. The best classification results were achieved using portable instruments, thus suggesting that an efficient and practical method for detecting the investigated food fraud might be further developed and deployed.