Monitoring beer during storage by fluorescence spectroscopy

The present study demonstrates the use of fluorescence spectroscopy and multivariate data analysis for monitoring changes in beer during storage. Total luminescence spectra and synchronous scanning fluorescence spectra were recorded for fresh beer and beer samples stored in clear glass vials for three weeks in darkness at 4 degrees C and at 22 degrees C, and exposed to light at 22 degrees C, respectively. A pronounced decrease of fluorescence features ascribed to riboflavin was observed in samples exposed to light as compared to those kept in the dark. Principal component analysis of synchronous scanning fluorescence spectra revealed clear clustering of samples according to storage conditions. Successful classification of differently stored samples was accomplished using both the nearest neighbour method (kNN) and linear discriminant analysis (LDA). (C) 2005 Elsevier Ltd. All rights reserved.