Study On Biochemical Characteristics Of Hordein In Brewing Barley

Composition and content variation of hordein storage protein, as well as endoproteinaseactivity of four barley cultivars (Ganpi.No.2, Ganpi.No.3, Gairdner and Schooner.) wereanalyzed. It is discovered that two domestic varieties presented higher hordein protein levelthan import varieties. Due to higher endoproteinase activity after steeping, the hordein level ofthe domestic varieties was subject to decrease fast, then equal or less to the imported in theend of germination. it suggest that the domestic cultivars is proatential to manufacture highquality malt.Proteinase activity, composition and content of hordein storage protein which wereaffected by pH and metal ions stress was investigated in order to further understandproteolysis of hordein. It was seen that appropriate pH environment and metal ionsconcentration during germinating increased proteinase activity, consequently promotedproteolysis of hordein too. It can be applied to Shorten malting time cycleBarley seed protein fractions, such as albumin, globulin, prolamin and glutenin weresuccessively extracted by using different solvents, and mashed with malt separately. It isshown that the hordein fractions had negative influence on quality indexes of wort. Somepolypeptides that may be hydrolysate of non-gel-forming hordein induced haze to wort.However, the gel-forming hordein is a factor which leads to filtration difficulty.Proteolysis of several proteinase with different substrate specificity (papain, trypsin andpepsin) to hordein was researched. All hydrolysates were analyzed by SDS-PAGE. The resultsindicated that the serine proteinase is effective to non-gel-forming hordein, as well as thecysteine proteinases to gel-forming hordein.