Recent trends on the use of infrared spectroscopy to trace and authenticate natural and agricultural food products

Verification of the authenticity of natural and agricultural foods has become a potential application of spectroscopic methods such as ultraviolet (UV), visible (VIS), near infrared (NIR), and mid-infrared (MIR). Adulteration can take many forms, including the addition of sugars, acids, volatile oils, overdilution of concentrate, addition of juices of other fruits, use of concentrate in a fresh product, and use of low-quality product recovered from what are normally waste products of manufacture. Food adulteration has been practiced since ancient times but has become more sophisticated in the recent past. Foods or ingredients most likely to be targets for adulteration include those that are of high value or subject to the vagaries of weather during their growth or harvest. The practice of adulteration commonly arises for two main reasons: firstly, it can be profitable, and secondly, adulterants can be easily mixed and are subsequently difficult to detect. To counter this problem, manufacturers subject their raw material and by-products to a series of quality controls, including high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), enzymatic tests, and physical tests. This mini-review highlights recent applications on the use of NIR and MIR spectroscopy to trace and authenticate natural and agricultural products.