TOTAL AND INDIVIDUAL BARLEY (1-3), (1-4)-BETA-D-GLUCANASE ACTIVITIES IN SOME GREEN AND KILNED MALTS

Total beta-glucanase activity was measured in extracts of malts prepar ed from three winter and three spring cultivars of barley. Samples wer e taken at intervals during modification and, after 116 hr, from malt kilned to 65-degrees-C. Good malting varieties showed highest levels o f total beta-glucanase activity, with a high correlation (r = 0.926** ) with HWE. Angora had the highest activity in the intermediate stages of malting, least loss of activity after heating extracts to 48-degre es-C for 10 mins and least loss of activity on kilning. Separation of isozymes by HPLC9 confirmed the greater heat stability of isozyme II, but, unlike previous studies on Australian cultivars, we found conside rable activity of isozyme I after kilning, even up to 85-degrees-C. Ho wever, total beta-glucanase activity was destroyed by heating extracts of all varieties to 60-degrees-C. Angora showed the highest proportio n of total activity as isozyme II after kilining. Cultivar differences suggested some scope for breeding varieties with increased total acti vity by combining high activities of each isozyme. The high correlatio n of total activity with HWE suggests beta-glucanase activity as a rap id test of malting quality.