Variation in the Biochemical Composition of Acid Extracts From Barleys of Contrasting Malting Quality

Abstract

Acid extracts from barleys of poor malting quality were characterized by high viscosity caused by enhanced concentrations of high molecular weight carbohydrates of which more than 80 per cent was /7-glucan. Up to 67 per cent of the j3-glucan in these barleys was soluble in the acid extract ing solution. In contrast, only about 25 per cent of the /3-glucan in good malting barleys was soluble, resulting in extracts having low viscosity. No evidence was found for autolysis in any of the extracts, and extracts from good malting varieties were characterized by high concentrations of fructose and sucrose. Protein concentration in the extracts varied little, although the protein content of the barleys ranged from 9-1 per cent to 15-4 per cent. Soluble protein has no effect on extract viscosity or the gel filtration properties of the carbohydrates. Some quantitative variation in acid-soluble and salt-soluble proteins was seen after electrophoresis on polyacrylamide.

Selection and characterization of low β-glucan mutants from barley

“…Two (M-737, M-1460) were low in total I~-glucan content, while the others (M-699, M-892) contained relatively high levels of total lS-glucan, confirming the earlier observations that the ratio of soluble to total 13-glucan in barley varieties can vary significantly (2,3,29). The reason for this is uncertain, but it is apparent that little or no 13-glucan soluble at pH 1.5 is synthesised in the four mutant lines.…”

“…A low viscosity of acid extracts of barley flours has been shown to indicate low [3-glucan content and good malting quality (2,15,24), although the overall correlation between viscosity of acid extract and total ~-glucan is poor (2,29). In the present study, however, a quick screening method based on barley extract viscosity (2) was used successfully in the search for low ~-glucan mutants of the high 13-glucan barley variety, Minerva.…”

“…This may be due to the warmer and drier S. AASTRUP: LOW I~-glucan barley mutants (17) and higher levels of total 13-glucan content. Very low viscosities of the acid extracts are seen for all the selected lines, which implies that they have very little acid soluble fS-glucan (2,29). The low viscosities are paralleled by large decreases in total 13-glucan content for the mutants M-737 and M-1460 compared with Minerva, while M-699 and M-892 show a smaller decrease.…”

Relationships Between Fructans Content and Barley Malt Quality

“…Recent studies reported that an interesting feature of the composition of malt extracts is the very small variation in the total carbohydrate concentration, particularly for the hexose sugars where the large variation in β-glucan and starch content is offset by differences in the concentration of simple sugars (Smith and Morgan 1980). These sugars are principally fructose, sucrose and glucose, and it has been suggested that the concentrations are highest in extracts from the better malting varieties (Smith and Morgan 1980;Cozzolino et al 2014a, b).…”

The molecular weight distribution of β-glucan in wort from malts of different barley varieties at different stages of malting

“…SMITH et al (20) suggested that the ratio between the HMW and the LMW carbohydrate fraction from acid extracts of barley flour could disclose the malting potential of a barley genotype. Our results show a similar distinction, i.e.…”