Research Of Pressure Immersion Of Barley On Malt Preparation Technology

Malt preparation is an important part in beer brewing. Previous study on malt preparation process was carried out under atmospheric conditions, however, there was mentioned rarely that control the growth of the malt by using pressure in the paper. This paper using the pressure soak method, through testing on the indexes of germination of barley under different pressure, discussing the influence on barley germination process by different pressure immersion, so as to develop the method of control the malting process by pressure, and build the fundation on the study of barley immersion by pressure malt preparation technology.In the barley immersion by pressure and germination process, through the detection of moisture degree of barley, hormones, organic acids and enzyme activity of malt indexes, and exploring the effect on barley germination process by pressure immersion. The main results are as follows:1. The effects on moisture degree of barley and malt indexes by pressure immersion process:the appropriate pressure can shorten the barley immersion time. Taken the twice wet and twice dry process, reached43%moisture degree of barley in0.05MPa and0.10MPa could save eight hours, reached38%moisture degree of barley in0.05MPa and0.10MPa could save four hours. It has bad influence on malt dissolving and protein dissolving and wort viscosity when the pressure increasing. But there has little impact on the quality of the malt by the lower pressure.2. The effects on hormone, enzyme activity and organic acids by pressure immersion process. With the pressure increasing, the content of gibberellin, auxin and abscisic acid were decreased, and the enzyme activities of phytase, a-amylase, protease, β-glucan were decreased, however, the enzyme activities of β-amylase and polyphenol oxidase were increased. The content of organic acids were changed by increasing pressure, the content of succinic acid, malic acid and lactic acid were decreased. For citric acid, the maximum content value of0.05MPa group higher than normal group150mg/L, while the overall content of0.10MPa and0.15MPa groups lower than normal group.3. There had better control of the malt growth rate by pressure. For phytase, amylase, protease, β-amylase and polyphenol oxidase, the maximum enzyme activities value of0.10MPa and0.15MPa groups later than0.05MPa and normal groups24hours, and the overall tendency was similarity. So it caused some delayed function on the changes of the enzyme activities in malt by a certain intensity pressure, to some extent, it can control the growth rate of malt. And it has a great function in malt preparation.