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ENZYMIC QUANTIFICATION OF (1→3) (1→4)‐β‐ D ‐GLUCAN IN BARLEY AND MALT
Author(s) -
Mcclear Barry V.,
GlennieHolmes Malcolm
Publication year - 1985
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1985.tb04345.x
Subject(s) - glucan , chemistry , glucose oxidase , degree of polymerization , hydrolysis , food science , chromatography , beta glucan , wheat flour , biochemistry , enzyme , organic chemistry , polymerization , polymer
A simple and quantitative method for the determination of (1→3) (1→4)‐β‐ D ‐glucan in barley flour and malt is described. The method allows direct analysis of β‐glucan in flour and malt slurries. Mixed‐linkage β‐glucan is specifically depolymerized with a highly purified (1→3) (1→4)‐β‐ D ‐glucanase (lichenase), from Bacillus subtilis , to tri‐, tetra‐ and higher degree of polymerization (d.p.) oligosaccharides. These oligosaccharides are then specifically and quantitatively hydrolysed to glucose using purified β‐ D ‐glucosidase. The glucose is then specifically determined using glucose oxidase/peroxidase reagent. Since barley flours contain only low levels of glucose, and maltosaccharides do not interfere with the assay, removal of low d.p. sugars is not necessary. Blank values are determined for each sample allowing the direct measurement of β‐glucan in maltsamples.α‐Amylasedoes not interfere with the assay. The method issuitable for the routineanalysis of β‐glucan in barley samples derived from breeding programs; 50 samples can be analysed by a single operator in a day. Evaluation of the technique on different days has indicated a mean standard error of 0–1 for barley flour samples containing 3–8 and 4–6% (w/w) β‐glucan content.