VARIETAL DIFFERENCES IN BARLEYS AND MALTS: VI. AUTOLYTIC PROTEOLYTIC ACTIVITY OF MALT AND ITS CORRELATIONS WITH WORT NITROGEN AND BARLEY NITROGEN FRACTIONS

Abstract

The proteolytic activity of 144 samples of malt, representing 12 varieties grown at 12 experimental stations in Canada, was determined by an autolytic method. Certain varieties differed widely in average activity (Olli, 291; O.A.C. 21, 235; and Wisconsin 38, 150 units), those of poor malting quality tending to give low values. The spread between station means was also large (Beaverlodge, 284; and Nappan, 149 units).The correlations between proteolytic activity, barley nitrogen fractions, total barley nitrogen, and wort nitrogen (data given in an earlier paper), were also studied. Intra-varietal partial correlations independent of total nitrogen, between proteolytic activity and nitrogen fractions, were all insignificant. Corresponding inter-varietal partial correlations were insignificant for insoluble and alcohol-soluble nitrogen, but highly significant for salt-soluble barley nitrogen and wort nitrogen. A close inter-varietal relation was found between proteolytic activity and salt-soluble barley nitrogen, and it was impossible to demonstrate that these two properties influenced wort nitrogen independently.