The importance of starch in brewing

Through a number of our research projects, we have explored the variation in barley, and the resultant malt starch structure; how this variation affects the malt gelatinisation temperature in a mash, and the fermentable sugar profile from the mash.  

Current malt specifications give data on extract and fermentation potential, along with diastatic power and usually alpha-amylase. But there is rarely any data on the gelatinisation temperature and the speed of gelatinisation in a mash. These two parameters are critical in understanding how the quickly starch is solubilsed and, as a consequence, how the starch hydrolysing enzymes can efficiently degrade starch.  Our results show variation in the average length of amylose and amylopectin chains influence the gelatinisation temperature in a high temperature 65^oc mash.  

The final fermentable sugars profile, especially maltose, are positively influenced by shorter chain lengths and or lower mashing temperatures. Beta-amylase was the enzyme most correlated to maltose production. The chain length of adjuncts also influence the fermentable sugar profile. Other traits that also play an important role are barley grain size and protein .content. Our results highlight the importance of barley (and solid adjunct) starch structure or at least malt parameters such as gelatinisation temperature should be considered as key malt parameters.

Dr Glen Fox

Centre for Nutrition and Food Sciences, QAAFI

Dr Glen Fox joined QAAFI’s Centre for Nutrition and Food Science in October 2010, after 25 years of conducting research projects with the Queensland Government. He obtained his PhD from Southern Cross University in the area of barley genetics related to barley and malt quality.
His research in barley, malt and brewing quality over many years has seen numerous outcomes for the Australian and international malting and brewing industries. He was elected as a Fellow of the Institute of Brewing & Distilling in 2018. The IBD is one the oldest international professional societies, established in 1886. Fellows are recognized as distinguished IBD members with substantial experience and responsibility in the field of brewing, fermentation, distilling or associated activities. They are likely to have shown dedicated service to the IBD and associated industries over many years.