Research On The Characterization Of Saccharomyces Cerevisiae In High Gravity Beer Brewing

High gravity brewing technology could improve beer production, beer smoothness, flavor stability and reduce capital, energy cost without expansion of the equipment. The research of high gravity brewing is meaningful to beer industry.During high gravity brewing, the yeast are exposed to relatively extreme conditions, such as high substrate concentration, high osmotic pressure and increased toxicity of produced ethanol, which decrease yeast fermentation performance. The characterizations were compared in different gravity wort, different ways of propagated yeast and different generations in high gravity brewing. By analyzing the reducing sugar, ethanol, diacetyl and the degree of fermentation during the high gravity brewing, the results are as follows.1. In12°P and20°P wort, the yeast almost can’t propagate when the alcohol content was14%; but it can in the alcohol content of12%, the propagation of the yeast in12°P and20°P wort was only1/4and3/4compared with it in non-alcohol.2. During different wort gravity fermentation, the yeast subjected to inhibitory effect in20°P fermentation compared with12°P fermentation, so the propagation, viability and fermentation performance of yeast decreased obviously.3. The yeast propagated in12°P wort at first level and propagated in16°P wort at second level had high rate of propagation and reducing sugar, stable rate of assimilating a-amino nitrogen, high degree of fermentation and cell viability, it could be well adapted for20°P wort fermentation.4. During high gravity wort fermentation, the yeast had higher rate of reducing sugar and deoxidating diacetyl, higher degree of fermentation and cell viability in the first and second generation. But all these properties mentioned above decreased obviously, and the intracellular trehalose increased a lot from third generation, the yeast was not fit for further fermentation.5. Storing yeast in5°P wort,10°P wort and sterile water, the concentration of intracellular trehalose increased the least in5°P wort, more in10°P wort, and the most in sterile water, but all increased sharply after6days storage and not fit for storing any longer.