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THE INFLUENCE OF LIPIDS DERIVED FROM MALT SPENT GRAINS ON YEAST METABOLISM AND FERMENTATION
Author(s) -
Taylor G. T.,
Thurston P. A.,
Kirsop B. H.
Publication year - 1979
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.2050-0416.1979.tb03911.x
Subject(s) - yeast , fusel alcohol , chemistry , fermentation , phospholipid , biochemistry , food science , free amino nitrogen , fatty acid , lipid metabolism , membrane
The addition to wort of lipids derived from malt spent grains had a pronounced effect on yeast metabolism. The lipids allowed the fermentation of de‐oxygenated wort and also stimulated yeast growth and the corresponding rate and extent of fermentation of air‐saturated wort by yeast strains having a high oxygen requirement. The lipids increased the fusel alcohols content of beer and decreased the content of esters and medium chain‐length fatty acids. The yeast incorporated sitosterol and unsaturated fatty acids from the spent grain lipids and the unsaturated fatty acids changed the pattern of fatty acids and sterols synthesized by the yeast. The fatty acids were present in the spent grain lipids mainly as triglycerides, free fatty acids and phospholipids. Using pure lipid compounds it was shown that the triglycerides were inactive and that the spent grain lipids exerted their effect on fermentation through the synergistic action of free unsaturated fatty acids, sitosterol and phospholipid. Phospholipid could be replaced by the detergent, Triton X‐100. The effect of the lipids on the synthesis of esters, fusel alcohols and medium chain fatty acids could be explained solely by their content of unsaturated fatty acids.