Exploring common and distinct information among three different kinds of NIR instruments by means of chemometrics

Food fraud is an old but still common and widespread problem that affects almost any type of food commodity sold on the market. Products may be mislabelled or counterfeit and, in many cases, it can be very difficult to detect these illegal practices. For this reason, quick and reliable methods are needed for efficiently tackling this problem. Due to its ease of use and rapidity, near-infrared (NIR) spectroscopy is particularly suitable for the purpose. In this study, the subtle differences between fresh and thawed cephalopods were investigated using different NIR instruments to collect the data and different chemometric approaches to perform the data analysis. Fifty fresh cephalopod specimens of both cuttlefish (Sepia officinalis) and musky octopus (Eledone spp.) were collected directly at the 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. Data collection was performed by measuring the same specimens using three different NIR spectrometers: one portable low-cost instrument (SCiO by Consumer Physics), one portable moderately highcost instrument (MicroNIR by Viavi), and one benchtop instrument (MPA by Bruker). The common and distinct information among the three data sources was investigated by means of a mid-level data fusion approach (Borràs et al., 2015) and by means of methods such as CovSel (Covariance Selection–Roger et al., 2011) and ComDim (Common Dimensions–Cariou et al., 2019). Differently from other traditional techniques employed for counteracting fraud, NIR spectroscopy coupled with chemometrics proves a robust approach for distinguishing between fresh and frozen cephalopods. Similarities and differences among the three NIR datasets, unravelled by the tested chemometric tools, reflect the building characteristics of each instrument and provide a complementary picture of the specimens’ evolution during the freeze-thaw process.