Yeast nutrients and beer quality.

Hsu, W.P., Vogt, A. and Bernstein, L.

Abstract
Variation in fermentation time and flavour amongst batches of beer apparently made in an identical manner are not uncommon. The reason seems most likely to be variations in essential minor components required by yeast especially where high adjunct levels are used. To test this idea a number of beers were produced on a four gallon scale using a 60% malt grist. A complex, but incompletely specified, mixture of yeast nutrients were added to the experimental worts. By and large the addition of the nutrients improved fermentation behaviour especially as the yeast went into successive generations. The flavour of the experimental beers was preferred to the control beers in all cases by a tasting panel. The composition of the nutrient mixture is based on information from published work. Main components include amino acids, vitamins, proteolipids and salts. The work suggests that in some cases the alpha amino nitrogen level of a wort may not be a reliable guide to yeast growth and fermentation behaviour.
Keywords: beer fermentation growth high gravity brewing nutrient quality wort yeast