Beer Yeast Extract

China is one of the largest countries in beer production and consumption, with an annual beer yield of more than 35 million tons, which produces approximately 700,000 tons of spent brewer's yeast mud. But most domestic breweries don't make full use of the spent brewer's yeast mud but discharge it directly as waste, or just make utilization of low additional value. That is not only a waste of resource but may also cause pollution to the environment.We obtain yeast extract from spent brewer's yeast mud, with the breaking-up of yeast's cell as the first step. There are lots of approaches to break up cell walls nowadays but considering food safety of yeast extract, several potential hydrolyzing methods and the most optimized hydrolyzing conditions are studied in this paper.Four degrading methods including yeast autolysis, hydrolysis by papain, hydrolysis by neutral proteinase and hydrolysis byβ- glucanase are applied successively to break up the cell walls and degrade macro molecules into small soluble ones. Then we confirm the most optimized wall-breaking method and conditions according to protein dissolve rate of the yeast extraction solution and content ofα-amino nitrogen dealt with the four methods.As a result, we found that the best dissolution result of spent brewer's yeast is acquired when usingβ- glucanase, and the most optimized conditions are: temperature at 55℃, pH5.5, 0.4% glucanase added and reaction for 32 hours; Product obtained after debitteration with 0.5% NaHCO3 in net weight shows a yellow color and is powder-like, which has a good taste and thick freshness, and has a unique, meat-like smell.