Stan Duke

Duke-Stan Professor
(608) 262-6527
shduke@wisc.edu
246 Moore Hall

Program Description:
My research program is focused on the improvement of barley malt quality. The bulk of the research is involved in study of amylolytic enzymes (α- and β-amylases, α-glucosidase, and starch debranching enzyme [limit dextrinase]) which degrade starch to fermentable sugars. Also, significant effort has been spent on new technologies for predicting malt quality and performance in mashing (the production of fermentable sugars in the mashing tun which is the first stage of brewing). The most significant recent results are (1) that the use of osmolality measurements are better predictors of sugars produced in mashing, amylolytic enzyme activities, and other measures of malt quality than malt extract, which has been the standard and most important measure of malt quality for more than 200 years. (2) That the endosperm specific β-amylase Bmy1 intron III variation is not an indicator of β-amylase activity or thermostability in North American germplasm (this contradicts several European, Japanese, and Australian studies). We have published papers on this topic in journals aimed at plant breeders and geneticists, molecular biologists, and those involved in malting and brewing. (3) That the endosperm specific β- amylase (Bmy1), rather than ubiquitous β-amylase (Bmy2), is by far the predominant β-amylase in barley grain (this contradicts a recent paper in Plant Physiology which used inappropriate probes) (4) D-enzyme was determined to be in malted barley.

Research in progress includes (1) Studies on the role of D-enzyme (i.e. disproportionating enzyme, 4-α-D-glucanotransferase) in fermentable sugar production during mashing (with C. A. Henson), (2) Studies on QTL mapping of osmolyte concentration in mashing (with C. A. Henson and R. Horsley), (3) Studies on improvements in barley malt quality from pre-Prohibition to the present (with C. A. Henson and H. E. Bockleman), (4) Metabolomic studies on winter barley acclimation (with C. A. Henson and P. M. Hayes), and (5) Studies on barley grain water sensitivity (with C. A. Henson and P. M. Hayes).