fluorescence spectroscopy (3)

10928452292?profile=RESIZE_710x

Walnut oil (WNO) is a high value vegetable oil with high nutritional value. This study developed a method based on excitation–emission matrix fluorescence (EEMF) spectroscopy coupled with chemometrics and ensemble learning to authenticate WNO, and semi-quantify the adulteration with other vegetable oils. A total of 711 vegetable oil samples were analysed by EEMF of which 426 samples were pure WNO. The classification models were established by chemometrics and ensemble methods. The ensemble methods achieved better classification performance, and PLS (partial least squares) regression was applied to semi-quantify the adulteration levels of walnut oil, especially with rapeseed oil (RSO).

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This study used Fourier transform infrared spectroscopy (FTIR), visible near-infrared spectroscopy (Vis-NIR) and excitation-emission matrix fluorescence spectroscopy (EEMs) combined with chemometrics to distinguish different types of edible vegetable oils. A set of 147 samples of five vegetable oils from different brands were analysed by the three different spectroscopic methods. After chemometric analysis of the spectra, the total correct recognition rate of the training set and prediction set of FTIR spectra was 100% for both, and for Vis-NIR spectra was 100% and 97.6% based on the PLS-DA method. However, the total correct recognition rate of training set and prediction set of EEMs data based on N-PLS-DA method was only 69.39% and 75.51%, respectively. The comparative study showed that FTIR and Vis-NIR combined with chemometrics were more suitable for vegetable oil species identification than EEMs technique, probably because of a small amount of fluorophores in the oils.

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Fish and meat are highly perishable foods, requiring both proper technologies for quality preservation and rapid methods for analysis. In this review, the most commonly applied techniques to preserve the quality of fish and meat products are first presented. The main methods used to assess both quality and authenticity of such products are then discussed. A special focus is placed on the fluorescence spectroscopy as a rapid, non-destructive, highly sensitive and selective technique, which can indicate the effect of different presevation methods on quality and authenticity.

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