Structural Changes of Starch Molecules in Barley Grains During Germination

Abstract

The germination of barley grains is an important step in malt production for beer brewing. This study examines the changes in starch molecular structure in barley grains under optimal conditions for sprouting. Two barley varieties were tested: Schooner and Grimmett, which are low and moderate dormancy grains, with >90 and <5% of grains germinating within two days in sprouting conditions, respectively. The barley grains were germinated in humid conditions after being soaked in excess water for 24 h. The grain weight and starch content of Schooner decreased significantly (P < 0.05) with germination time, whereas those of Grimmett showed no significant changes (P > 0.05). The starch chain‐length distributions, analyzed from enzymatically debranched starch molecules with size‐exclusion chromatography, indicated that the shorter amylopectin branches of Schooner were degraded at a faster rate than its longer amylopectin branches, which was also confirmed by the decreasing degree of branching with germination time. The changes in starch molecular structure of Grimmett grains were less apparent. The results of this study showed that barley grains containing shorter starch chains can produce sugars more quickly, which indicates that starch structure can serve as one of the specifications when selecting barley grains for brewing.

The impact of barley nitrogen fertilization rate on barley brewing using a commercial enzyme (Ondea Pro)

“…In addition, this study did not attempt to measure starch or its composition (amylose: amylopectin, branching, etc) which is an emerging measure of barley and malt quality. Future studies would be expected to include these parameters once the importance of these parameters is understood in terms of brewing functionality . Finally, this investigation supports the contention that barley brewing is commercially possible and that barley with higher protein content has the capacity to produce beer that would meet the quality expectations of brewers.…”

Infrared spectral analysis of sugar profiles of worts from varying grist to liquor ratios using infusion and ramping mash styles

“…However, there is a preferred profile of fermentable sugars by yeast strains. This profile of sugars in the wort comes from barley starch and some non‐starch polysaccharides .…”

The intrinsic and regulated proteomes of barley seeds in response to fungal infection

“…Sucrose synthase 1 (SUS1) and sucrose synthase 2 (SUS2) catalyse the conversion of sucrose with nucleotide activated glucose and fructose, and are key regulatory enzymes in the process of starch synthesis [42,43]. Increased sucrose synthase abundance in malting barley is consistent with selection for high starch content and starch structure more suited to hydrolysis during the malting and brewing process [44]. To our knowledge, this is the first time that proteomic differences have been identified .…”