A FTIR microspectroscopy study of autolysis in cells of the wine yeast Saccharomyces cerevisiae

The present paper reports the first application of FTIR microspectroscopy in the mid-infrared range to study the major biochemical changes associated with autolysis in yeast cells. Measurements were done both in transmission and in attenuated total reflection (ATR) mode on cells of Saccharomyces cerevisiae strain EC1118 before and after induction of the autolytic process in a model wine medium and in a Chardonnay base wine. Unsupervised multivariate statistical analysis (Hierarchical Cluster Analysis and Principal Component Analysis), as well as accurate spectral analysis based on curve fitting, were applied to the acquired spectra. The spectral behaviour of S. cerevisiae in the model and base wines was found to be the same. A detailed interpretation of absorption bands was given by reference to the literature and through comparison of transmission and ATR spectra. It was shown that FTIR microspectroscopy is a rapid and accurate tool to simultaneously probe the major biochemical events associated with the autolytic process. Moreover, the intrinsically higher sensitivity of ATR with respect to transmission spectra in analyzing autolysis was also demonstrated.