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Re‐Assessment of the Half‐Grain Modification Method for Assessing Malt Modification
Author(s) -
Sá Roberta M.,
Palmer G. H.
Publication year - 2005
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.2050-0416.2005.tb00663.x
Subject(s) - mashing , endosperm , glucan , starch , food science , germination , chemistry , polysaccharide , horticulture , biochemistry , biology
The half‐grain mashing (modification) method proposed by Palmer (J. Inst. Brew., 1975, 81: 408) was reassessed. The intention was to quantify the differences in malt modification in terms of β‐glucan breakdown and clarify the relationship between β‐glucan breakdown and overall modification of the endosperm during malting. This was carried out at 45°C as well as at 65°C, the percentage of weight loss was recorded and the endosperm residue was analysed for β‐glucan content. In general, weight loss was related to modification. Samples, which were modified at higher levels, lost significantly more material during the half‐grain mashing procedure than those which were under‐modified. At a malting process time of 96 h all the varieties had similar weight loss. After mashing the half grains, the β‐glucan contents of the grain residues showed an apparent increase because of loss of non‐β‐glucan materials. However, over the malting period β‐glucan decreased. Chariot malted faster than the other varieties studied. The β‐glucan levels of this variety were reduced by 78% between 48 and 72 h of germination. Significant levels of β‐glucan were degraded and large quantities of starch and protein were released. During the same period of germination, the corresponding samples of Decanter did not show a significant reduction in β‐glucan levels. In contrast, Brazilian variety MN698 lost endosperm material and β‐glucan rapidly by 48 h. These early results suggest that during malting, extract solubilization may or may not accompany β‐glucan breakdown. Therefore, β‐glucan levels in malt cannot be used as an overall index of modification of the endosperm.