Application Different ¦Á-acids To Improve The Study Of The Beer Fermentation Process

Hops is one of essential raw materials of beer fermentation. its main role is to provide the bitter taste for beer, and another one is bactericidal anti-corrosion. The bitter taste of beer is mainly from iso-a-acid which is transformed from isomers of a-acid in hops. The whole hops are added during wort boiling in traditional beer fermentation. The shortcoming of this process is that the a-acid in hops need to be boiled for a long time for stripping and generating iso-a-acid. Because of the effects of protein and other substances, final utilization is only 1/3.In this study, I extracted hops concrete (a-acid extract) with supercritical CO2 extraction apparatus, isomerizated a-acid extract in advance in boiling water bath, and extracted hop polyphenol with ethanol at the same time. Then both of them are added to the wort boiling. The purpose is to enhance the degree of isomerization of a-acid and reduce the cost for beer production.The results shows that the optimized condition using supercritical CO2 for hops concrete is: pressure 25MPa,temperature 40℃, time150mins, CO2 flux 45 kg/h, the rate of obtains is 6.47%;the optimal conditions ofα-acid isomerization in advance is: paste water ratiol:300, reflux time45mins, pH10, the rate of isomerization is 69.65%; the optimal conditions of extracting hop polyphenol with ethanol is: ethanol concentration 60%, liquid ratio 1:60, reflux time 60mins, the temperature of water bath 70℃. The rate of obtains is 4.79%.After improving the process of beer fermentation with iso-a-acid, the rate ofα-acid is 2.4 times as more as adding to the whole hops, and the main chemical indicators in the beer are in line with the national standard.