EFFECT OF SERIAL REPITCHING ON THE FERMENTATION PROPERTIES AND CONDITION OF BREWING YEAST

On completion of a brewery fermentation, the yeast crop is removed fro m green beer, stored, and repitched. The effect of serial repitching o n yeast inoculum condition and its subsequent fermentation performance is important but not well characterized. The physical properties of t he brewing yeast cell surface influence flocculation and may be used t o ascertain the physiological state of the cell. Cropped yeast from pr oduction and laboratory-scale fermentations have been examined. The ef fect of serial repitching on the physical properties of a production a le strain was monitored using dye retention, latex microsphere attachm ent, electron microscopy, and fluorescent dye techniques. The floccula tion of each generation was determined. It was observed that a correla tion between cell surface condition and fermentation performance exist ed. It is suggested that cell surface condition may be used to predict the fermentation performance of the subsequent pitch.