14. Barley starch—It’s not about quantity but the quality (Does size matter?)

Glen Fox (1); (1) The University of Queensland, Toowoomba, Australia

Technical Session 4: Barley & Malt I
Sunday, August 14  •  2:00–3:15 p.m.
Tower Building, Second Level, Grand Ballroom

Barley starch is the main source of fermentable sugars required for fermentation in brewing. For decades, researchers have measured total starch content and/or amylose content only to be left unsure as how to quantify the contribution of total starch or the starch polymers (amylose and amylopectin) to malting and brewing quality. Further, barley breeding programs have focused on increasing the level of starch-degrading enzymes without really understanding the starch substrate. We now can show there is considerable variation in starch structure (both amylose and amylopectin) in barley. The variation in the length of glucose chains and degree of branching influence the rate of fermentable sugar release. The structure of starch in solid adjuncts also influences the addition of fermentable sugars. Currently, the standard barley specifications show no relationship to starch quality, while large grain size does not tell us anything about the size of the starch polymers and high starch content (low protein) is as equally uninformative. Many researchers have previously shown the lack of correlation between barley and malt specifications and brewing performance. We will show the potential to use starch structure as a means to better understand the fermentable sugar profile. In addition, the focus for breeders may be to fine-tune starch structure rather than just increasing starch-degrading enzyme levels.

Glen Fox joined the University of Queensland’s Centre for Nutrition and Food Science in October 2010, after 25 years of conducting research projects with the Queensland government. He obtained his Ph.D. degree from Southern Cross University in the area of barley genetics related to barley and malt quality. In 2008-2009, he was a postdoctoral fellow at the Department of Food Science, Stellenbosch University, South Africa, and appointed adjunct professor in 2012. In 2013, he was appointed to the College of Experts for the Global Change Institute at the University of Queensland. He has a vast amount of knowledge in value-adding of cereals, particularly barley, malt and beer quality, including starch structure and fermentability. He has collaborated with major global brewing companies and partnered in all the Australian states, the United States, Canada, South Africa, China, Ethiopia, Kenya and the United Kingdom. Glen also has research activities on maize and sorghum covering food security in several African countries. Glen is on a number of national and international technical committees, including the Institute of Brewing & Distilling Asia Pacific Section Analytical Methods Sub-committee and the European Brewery Convention Brewing Science Group.