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Amino Acid Permeases and their Influence on Flavour Compounds in Beer
N. James and U. Stahl

Amino acids are the chief source of assimilable nitrogen in wort. Beer flavour is highly influenced by wort nitrogen content and their utilization by yeast. Amino acid permeases that transport amino acids into the yeast are regulated by two mechanisms namely SPS-sensor complex (Ssy1-Ptr3-Ssy5) and nitrogen catabolite repression (NCR). Various by-products and metabolites like alcohols, esters, organic acids, aldehydes and ketones from beer fermentation contribute to beer flavour. Sufficient FAN amounts, nitrogen combinations in the wort and a good understanding of the regulation of amino acid permeases help promote adequate growth and a good flavour profile during alcoholic fermentations.

Descriptors: fermentation; nitrogen; amino acid permeases, flavour

BrewingScience Monatsschrift fr Brauwissenschaft, 67 (September/October 2014), pp. 120-127