EFFECT OF ENVIRONMENTAL-CONDITIONS ON FLOCCULATION AND IMMOBILIZATIONOF BREWERS-YEAST DURING PRODUCTION OF ALCOHOL-FREE BEER

A method using immobilised yeasts has been developed and successfully applied for production of alcohol-free beer. The influence of environm ental conditions present during alcohol-free beer production on the fl occulation and immobilisation of the yeast Saccharomyces cerevisiae va r, uvarum was investigated in the present study. In wort, the cells de veloped flocculation at the end of exponential growth, according to th e NewFlo phenotype. In defined medium, the flocculation capacity appea red to be temporary and was lost rapidly during the stationary phase. No increase in cell wall hydrophobicity at the onset of flocculation w as observed in either medium. Low growth temperatures increased floccu lation capacity approximately four-fold, compared to growth at high te mperatures. The optimum temperature for flocculation was at 25 degrees C with cells grown at low or high temperature. A novel method using c arboxyfluorescein-stained cells was developed to analyse the initial a dhesion of cells to carrier. This method also allowed rapid analysis o f the effects of immobilisation to DEAE-cellulose carrier during alcoh ol-free beer production process. It appeared that a high flocculation capacity stimulated adhesion to the DEAE-carrier.