P-11
Relationships among starch-degrading enzymes, fermentable sugars and real degree of fermentation
Presenter: Dennis Langrell, Canadian Grain Commission, Winnipeg, Manitoba, Canada
Co-Authors: Michael Edney, Canadian Grain Commission, Winnipeg, Manitoba, Canada; and Yueshu Li and Robert McCaig, Canadian Malting Barley Technical Centre, Winnipeg, Manitoba, Canada

Levels of fermentable sugars in a wort should play a key role in determining fermentation efficiency of that wort. In turn, the starch-degrading enzymes, which produce the fermentable sugars and include alpha-amylase, beta-amylase, and limit-dextrinase, should also have an effect on fermentability. Reported research, though, has been inconclusive in determining the effect of fermentable sugars and enzyme levels on fermentability. However, in these studies, fermentability has often been quantified using low-gravity (Congress) worts with small-scale, forced fermentations. The present study used real degree of fermentation (RDF), as determined with commercial wort from a 3-hL pilot-scale brewery, to indicate fermentation efficiency. Commercial-quality malts, from two-rowed malting barley varieties (AC Metcalfe, Calder, CDC Copeland, CDC Kendall, CDC Select, Harrington, Newdale, Merit), were produced in a 50-kg pilot malt plant. Malts were reasonably well modified (wort beta-glucan less than 200 ppm, friability greater than 80%) and they showed significant variability in fermentability (61.8 – 72.0% RDF). Levels of fermentable sugars were found to have a greater effect on RDF and ethanol content than did the starch-degrading enzymes. Significant differences in enzymes were observed among the varieties, but some varieties with lower levels of enzymes had superior fermentability.

Dennis Langrell received a diploma in biochemical technology in 1975 from Red River College and a B.Sc. in chemistry in 1985 from the University of Winnipeg, both located in Winnipeg, Manitoba, Canada. He began employment with the Canadian Grain Commission's Grain Research Laboratory(GRL) in 1975, and has held several positions involving malting barley quality analysis and research. Since 1993, he has been employed as a malt quality chemist in the Applied Barley Research Unit of the GRL, reporting to Michael J. Edney. He has been a member of the ASBC since July of 2000.