FT-NIR analysis of different garlic cultivars

Abstract

Garlic represents a source of various biologically active phytomolecules. The content of phenolic compounds in garlic varies greatly with genetic, agronomic, and environmental factors, and the cultivar is the primary factor which determines this variation. The aim of this study was to analyse by Fourier transform near infrared spectroscopy (FT-NIR) different garlic cultivars, organically grown or commercial ones, coming from four different geographical areas. Garlic samples were collected from four different locations, and then analyse in the spectral range of the NIR radiation, which extends from 800 to 2500 nm, using three different modules (integrating sphere, transmission and fibre optic modules) that provide tools for analysing most liquid and solid samples. For all the measurements, no sample preparation was performed, since this analytical technique is non-invasive and non-destructive, and each sample was subject to repeated measurements. All the FT-NIR garlic spectra were undergone to a post processing analysis and compared between them. The comparison enhanced a clear distinction between biological and commercial garlic spectra. In particular, the last ones were characterised by a greater number of absorption peaks. This different trend in the FT-NIR spectra could be related to the possible contamination by toxic waste of the cultivation soil. Consumers are gradually looking for quality seals and trust marks on food products, and expected manufacturers and retailers to provide products of high quality. In this context, the FT-NIR represents a valid instrument for food classification and an important task for quality control and identification of foodstuff product adulteration.