The use of high-lysine malt in brewing.
The high lysine barley mutant 1508, a chemically induced mutant of the two rowed Danish variety BOMI, has been malted and brewed in laboratory, pilot and production scale trials. 1508 has a high lysine content due primarily to its relative lack of low lysine hordeins. Compared to the wild type it has a shrunken endosperm, lower kernal weight and reduced beta amylase, but 50% less beta glucan and greater alpha amylase activity. Although the total nitrogen concentration of malt derived from the mutant barley is normal, that of soluble nitrogen is double that of the wild type. Worts and beers produced from 1508 malt had twice the concentrations of total nitrogen, amino acids and high molecular weight nitrogen than did normal worts and beers. The relative molar amino acid composition of the two worts was however only marginally different. Because of its high nitrogen concentration, the mutant malt allows use of very high proportions of adjuncts in the grist. A pilot brewing of a grist containing 35% 1508 malt and 65% maize grits produced a beer comparable to that from a conventional grist of 65% Emir malt and 35% maize. The use of sucrose or of other 100% fermentable adjuncts in place of the maize grits facilitates the production of low carbohydrate beer without the use of enzymes. In full scale trials the beer produced in this way was comparable to that produced from normal wort with amyloglucosidase addition.
Keywords: barley beer brewing lysine mutant