Utilisation of front-face fluorescence spectroscopy for the determination of some selected chemical parameters in soft cheeses

摘要

This study evaluated the usefulness of front-face fluorescence spectroscopy for predicting some selected chemical parameters in soft cheeses in external (E) and central (C) zones. Fat, dry matter (DM), pH, total nitrogen (TN) and water-soluble nitrogen (WSN) contents were determined by reference methods. Tryptophan (excitation: 290 nm; emission: 305—450 nm), riboflavin (excitation: 380 nm; emission: 400-640 nm) and vitamin A fluorescence spectra (emission: 410 nm; excitation: 270-350 nm) were recorded on the investigated cheeses. Three separate prediction models were developed from the tryptophan, riboflavin and vitamin A spectra using partial least squares (PLS) regression and the leave-one-out cross-validation technique. The results showed that fat, DM, fat in dry matter and WSN were the best predicted with the vitamin A fluorescence spectra models providing the highest values of the determination coefficient (R~2) of 0.88, 0.86, 0.86 and 0.84, respectively The prediction of the pH was also successful using riboflavin fluorescence spectra (R~2 = 0.85). The WSN/TN ratio can also be predicted from the three intrinsic probes, but with much lower precision.