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Impact of mashing conditions on extract, its fermentability, and the levels of wort free amino nitrogen (FAN), β-glucan, and lipids

Citation

Evans, DE and Goldsmith, M and Redd, KS and Nischwitz, R and Lentini, A, Impact of mashing conditions on extract, its fermentability, and the levels of wort free amino nitrogen (FAN), β-glucan, and lipids, American Society of Brewing Chemists. Journal, 70, (1) pp. 39-49. ISSN 0361-0470 (2012) [Refereed Article]


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Copyright Statement

Copyright 2012 American Society of Brewing Chemists.

DOI: doi:10.1094/ASBCJ-2012-0103-01

Abstract

In a small-scale protocol, the mashing conditions used were found to have important influences on malt quality parameters, including extract, fermentability, and the levels of wort free amino nitrogen (FAN) and -glucan. Understanding this relationship is important in determining and prioritizing malt components for malt quality assessment. The impact of mash-in temperatures of 62.575.0C was assessed on a modernized small-scale mash program whose key parameters included grist milling at 0.7 mm by disc mill, addition of CaSO4 (0.3 mM) to water, grist/water ratio of 1:3, 60 min duration of the initial phase of mashing, and the completion of mashing at 74C. Wort -glucan and total protein levels were relatively stable, whereas FAN progressively decreased across the temperature range studied. Maximal fermentability was obtained at a mash-in temperature of 65C. It was observed that malts containing the most thermostable -amylase type, Sd2H, produced more fermentable worts and that these mashes maintained a greater degree of fermentability at the higher mash-in temperatures. At mash-in temperatures greater than 65C, extract slowly decreased, whereas the level of wort total fatty acids increased substantially. The levels of linoleic (C18:2) and linolenic (C18:3) acids increased, whereas the level of palmitic (C16:0) and stearic (C18:0) acids declined at mash-in temperatures above 65C. For yeast fermentation performance, C18:2 is a key nutritive component provided by wort. It was observed that malt samples from different barley varieties produced a range of levels of wort total fatty acid contents, although the greater proportion of this variation could be attributed to between sample variation at mash-in temperatures below 65C. However, at mash-in temperatures above 65C, the varietal sample became substantially more important in determining fatty acid content and composition. In both small-scale and commercial worts, wort boiling and trub removal reduced the level of wort fatty acids by up to 85 percentage points and increased the proportion of C16:0 while decreasing the proportion of C18:2. This effect of wort boiling was more variable with commercial brewery worts that were also more variable in the initial levels of total fatty acids and were not as consistent with respect to the extent of trub removal. In particular, the level and composition of wort fatty acids is well known to impact on yeast fermentation performance and generation of flavor-active esters. As such, brewers with a greater understanding of the determinants of the level and composition of the fatty acids in the wort from which they were brewing could potentially produce beer more efficiently and closer to their desired quality specifications.

Item Details

Item Type:Refereed Article
Keywords:Brewing, Lipids, Malt quality, Mashing
Research Division:Agricultural and Veterinary Sciences
Research Group:Crop and Pasture Production
Research Field:Crop and Pasture Biochemistry and Physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Winter Grains and Oilseeds
Objective Field:Barley
Author:Evans, DE (Dr David Evans)
Author:Redd, KS (Mr Kevin Redd)
ID Code:81326
Year Published:2012
Web of Science® Times Cited:7
Deposited By:Plant Science
Deposited On:2012-11-29
Last Modified:2013-05-14
Downloads:1 View Download Statistics

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