PITCHING RATE IN HIGH GRAVITY BREWING

The optimal pitching rate in high gravity worts (12-16-degrees-P) was about 0.3 g/l wet weight (2.3 x 10(6) counted cells/ml) and per one pe rcent of original wort gravity. In very high gravity worts (20-23-degr ees-P) the corresponding figure was 0.4 g/l (2.9 x 10(6) cells/ml). Hi gher amounts of yeast did not improve the fermentation rate. With incr eased original wort gravity, flocculation of the yeast weakened and th e amount of cropped yeast decreased. The viability of the crop yeast w as good. In the conditions used, excessive production of acetate ester s occurred only with pitching rates lower than the recommended rate. A s the original wort gravity increased, more fermentable extract was me tabolized to ethanol rather than utilized for yeast growth. The highes t ethanol yield obtained was 10.9% (v/v).