Applications of NIR Spectroscopy and Chemometrics for Food Authentication and Safety: Detection of Adulterants and Contaminants.

Adulteration and contamination represent an ever-growing global problem, due to the emergence of increasingly sophisticated illicit commercial practices involving high-value and widely consumed products. Traditional chromatographic methods, such as liquid chromatography coupled with mass spectrometry, offer high sensitivity but their application is often limited by long analysis time, complex sample preparation, and the use of non-eco-friendly organic solvents. In contrast, enzymatic and immunoassay-based methods are rapid and require minimal sample preparation, but their applicability may be restricted by antibody specificity and potential cross-reactivity. In this context, near-infrared (NIR) spectroscopy is a rapid, non-destructive technique that does not require the use of solvents and is becoming increasingly relevant in food analysis. This review provides an overview of the potential of this spectroscopic technique, coupled with chemometrics, for the detection of adulterants and contaminants in various matrices. After a brief summary of the principles on which it is based and the instruments that can be used, the chemometric processes useful for data interpretation have been discussed, as well as the main applications in liquid and solid food, including oils, milk, juices, spices, cereals, coffee, and dietary supplements. The analyzed case studies indicated that even very low levels (ppm) of adulterants and contaminants can be detected with high accuracy and sensitivity using models such as PLSR, SVM, RF, and CNNs and new and emerging devices such as portable ones.