Rapid assessment of neoformed compounds in nuts and sesame seeds by front-face fluorescence

Abstract

The potential of a rapid spectral method, based on front-face fluorescence, to monitor lipid neoformed compounds (NFC) during processing of nuts and sesame seeds was investigated. Fluorescence fingerprints were obtained from front-face fluorescence acquisition directly on crushed nuts and sesame seed samples obtained at different stages of processing. Fluorescence was very sensitive to physicochemical changes induced by the heat process, namely roasting. Parallel factor (PARAFAC) analysis of the fluorescence landscapes revealed four main fluorescence profiles in the nuts, and five in the sesame seeds. These were associated with peptidic tryptophan, tocopherols and process derived products. Various regression models between fluorescence spectra and NFC appearing during the process, carboxymethyllysine (CML) and trans fatty acids (tFA) showed good correlations ( R > 0.89) and satisfactory prediction errors (RMSECV < 1.67). When applied to indicators of lipid peroxidation, good regression models were also obtained allowing prediction of the pAV ( p-anisidine value) and TBARs (thiobarbituric acid reactive substances): R = 0.73 and 0.96 in nuts and sesame seeds, respectively, with prediction errors lower than 0.78. This study demonstrates the interest of front-face fluorescence as a promising tool for quality control of nuts and seeds roasting.