A. L. MACLEOD (1), M. S. Izydorczyk (1), M. J. Edney (1), J. T. O’Donovan (2); (1) Canadian Grain Commission, Winnipeg, MB, Canada; (2) Agriculture and Agri-Food Canada, Lacombe, AB, Canada

Malt
Wednesday, June 4 - 3:00 p.m.-4:45 p.m.
Level 4, Red Lacquer Ballroom

Different brewing practices require malts with different levels of diastatic power, depending on amounts of adjuncts, desired attenuation, and mouthfeel of the beer. In addition, the relative levels of various starch- and protein-degrading enzymes affect the fermentability of malt wort. Barley grown in western Canada is well known for its high content of protein, resulting in high levels and activity of various hydrolytic enzymes. However, excessive levels of grain protein lead to considerable quantities of Canadian malting barley being rejected by selectors. Breeders have strived to develop barley cultivars with low protein content while maintaining the desirable Canadian-type, high-enzyme malting quality. Recently, three such cultivars have been released: Bentley, CDC Meredith, and Merit 57. In the present study, the three cultivars were grown at five rates of nitrogen fertilization (0, 30, 60, 90, and 120 kg/ha), producing grain with a range of protein levels. AC Metcalfe and Major, two cultivars with normal grain protein levels, were included in the trials. Compared to AC Metcalfe and Major, cvs. Bentley, CDC Meredith, and Merit 57 showed reduced contents of grain protein, which resulted in higher malt extracts. The two higher protein cultivars, AC Metcalfe and Major, tended to have the highest levels of starch-degrading enzymes, but levels for Merit 57 were surprisingly high given the low grain protein content of this cultivar. The activity of individual starch-degrading enzymes alpha-amylase, beta-amylase, and limit dextrinase was also measured, and relationships with total diastatic power revealed complex interactions affected by factors such as cultivar, nitrogen application, and growing environment. A better understanding of the interactions among these factors will aid in the selection of new varieties to meet the needs of the modern brewer.

Aaron MacLeod is a chemist in the Malting Barley Research unit of the Canadian Grain Commission Grain Research Laboratory. The unit provides quality assurance for malting barley grown in western Canada and conducts research on factors affecting malting barley quality and quality measurement methods. Aaron is a member of the Prairie Recommending Committee for Oats and Barley and active ASBC member since 2008. He has participated in collaborative studies for numerous new methods and is currently serving on the ASBC Technical Committee. Aaron holds a B.S. degree in chemistry from the University of Western Ontario.