The Impact Of Two Kinds Of Bacteria Colonies On Malt And Wort Quality During The Malting Process

As one of the raw material of beer brewing, microbial communities on barley have a great impact on the processes of barley germination, quality of malt and beer brewing. During malting, these organisms have complex interactions, and causes barley and malt quality dropping. At the same time, it also causes adversely affect to beer, such as quality and taste can be change. As bacterial microbial communities are the main microflora on the barley, and it has not been reported on the impact of two communities of bacterial on barley so far, this experiment focus on the impacts of two bacterial communities(Gram-positive bacterial and Gram-negative bacterial) on the quality of barley, malt and wort.And hope to provide some reference to theoretical research and industrial production. The main contents are as follow:G+ and G- have little impact on the activity of a-amylase, but G- inhibits the activity of β-amylase. G+ promotes the activity of protease in early germination, but G+ and G- all inhibit it in the late germination. G+ and G- promote the activity of cellulose. G+ promotes the activity of phytase, and G- inhibits. At the end of germination, two communities all promote the activity of β-glucanase.G+ reduces the content of lactic acid, meanwhile, the contents of malic acid, citric acid and succinic acid have little changes. G- greatly reduces the contents of citric acid and succinic acid, and the contents of malic acid and lactic acid are slightly decrease.G+ and G- reduce the content of soluble protein at the end of germination. The content of salt-soluble protein slightly changes at the end of germination, G+ and G- primarily affect the content in the process of germination. G+ and G- discourage the dissolve of gliadin protein.G+ has little effect on the content of alkali-soluble protein and G- makes it higher than normal level at the end of germination.G+ and G- significantly affect the extract,library value, a-amino nitrogen and saccharification force of malt and wort. G- reduces 3.5% content of extract,3% content of library value and 28mg/100g a-amino nitrogen, these all below the superior grade standard of malt. G+ reduces 2.1% content of extract,1.8% content of library value,18mg/100g α-amino nitrogen and 12WK of saccharification force, these make the quality of malt decline.G+ and G- have little effects on chroma, viscosity, pH and total acid, but increase the turbidity.