Structural changes in starch molecules during the malting of barley.

Two cultivars of sorghum (red, RS and white, WS) were germinated at 25 or 30°C for 1, 2, or 3 days and were evaluated regarding enzyme activities (diastatic power: DP, b-amylase), chemical compounds (total starch, damaged starch, glucose, free amino acid), and bioactive compounds (free phenolic compounds: FPC and g-aminobutyric acid:GABA). For WS and RS (on third germination day at 30°C), DP was 11.3 AE 1.4 and 10.8 AE 1.3°DP, b-amylase activity: 33.0 AE 0.9 and 71.1 AE 0.7 UBetamyl/g d.b., respectively, while at 25°C, DP was 6.1 AE 0.7 and 18.0 AE 1.1°DP, b-amylase activity: 9.3 AE 0.5 and 57.8 AE 0.3 UBetamyl/g d.b., respectively. Starch degradation, free amino acids, and free glucose content increased during germination, and depended on cultivar, germination time and temperature. The hydrolysis of the protein matrix influenced the release of starch granules, which were more accessible to amylolytic action. FPC and GABA levels were higher after grain germination and depended on sorghum cultivar and germination temperature. Germination at 30°C for 3 days represented the most suitable conditions for obtaining good bio-functional sorghum malt.

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“…The loss of starch reached for WS on G3 (14 g/100 g d.b.) was similar to the percentage of loss of barley malt starch .…”

Section: Resultssupporting

confidence: 69%

“…These results suggest that protease activity was modified significantly by germination temperature, achieving greater activity at 30°C. Kano et al also observed a higher content of free amino acids in a variety of sorghum germinated at 30°C compared to 20°C.…”

Section: Resultsmentioning

confidence: 88%

Effects of malting conditions on enzyme activities, chemical, and bioactive compounds of sorghum starchy products as raw material for brewery

2016

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“…The starch structure considered in this study includes the molecular size distributions of individual branches (known as the chain-length distribution or CLD) and whole (fully branched) starch molecules obtained through sizeexclusion chromatography (SEC) equipped with differential refractive index detection, as well as the average degree of branching (DB) of starch molecules obtained through 1 H nuclear magnetic resonance (NMR) spectroscopy. Early work (Kano et al 1981;Bertoft and Henriksnas 1983) to describe the detailed changes in size distributions of starch molecules during malting probably had some technical limitations, such as the loss of partially hydrolyzed starch molecules during starch isolation owing to their high water solubility and the retrogradation of AM branches during SEC analysis in water. The loss of partially hydrolyzed starch molecules has been overcome here by using a technique that simultaneously dissolves starch molecules and removes nonstarch components in the grain without the need of preisolation of starch granules Syahariza et al 2010).…”

mentioning

confidence: 99%

Structural Changes of Starch Molecules in Barley Grains During Germination

et al. 2014

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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.

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“…This demonstrates that the first peak eluting from the chromatographic column is the branched amylopectin, while the relatively linear amylose was left intact. The lower molecular weight fragments from debranching amylopectin were found in two peaks located to the right of amylose in the chromatogram (data not shown) in a typical bimodal distribution pattern (Lii and Lineback 1977;Kano et al 1981). The series of chromatograms illustrated in Fig.…”

Section: Enzymatic Degradation Of Native Starchmentioning

confidence: 83%

Characterization of the Action of Bacillus Subtilus Alpha-Amylase on Sweet Potato Starch, Amylose and Amylopectin

Rupp

Schwartz

1988

J Food Biochemistry

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f i e action pattern of Bacillus subtilis alpha-amylase on Jewel variety sweetpotato starch, amylose and amylopectin was monitored using high peij4ormance size exclusion chromatography. A wide range of products, from high molecular weight polysaccharides to specific saccharides of low molecular weights, were observed. The hydrolysis pattern for amylose in starch was concealed by hydrolytic fragments formed from amylolysis of the greater quantity of amylopectin. Amylopectin was degraded to a more speciJic mixture of polysaccharide fragments. Changes in molecular size of hydrolytic fragments formed during amylolysis supported the cluster model praiously proposed for amylopectin. These results also suggest that the action of alpha-amylase on sweet potato starch is generally a nonrandom process, primarily resulting from enzymatic action on amylopectin. To support this hypothesis, a more random pattern of hydrolysis was observed from acid treated starch.

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Structural changes in starch molecules during the malting of barley.

Cited by 12 publications

References 1 publication

Effects of malting conditions on enzyme activities, chemical, and bioactive compounds of sorghum starchy products as raw material for brewery

Effects of malting conditions on enzyme activities, chemical, and bioactive compounds of sorghum starchy products as raw material for brewery

Structural Changes of Starch Molecules in Barley Grains During Germination

Characterization of the Action of Bacillus Subtilus Alpha-Amylase on Sweet Potato Starch, Amylose and Amylopectin

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