The effects of high protein levels in malt are discussed with particular reference to conditions in a microbrewery using pure malt mash. Although the free alpha amino nitrogen (FAN) content of the wort must be high enough to ensure adequate yeast nutrition and fermentation performance, an excess may lead to the production of large quantities of volatile compounds such as esters, higher alcohols and diacetyl, which can result in the flavour impressions produced by these compounds being too strong to suit consumer preferences. Moreover, if the total nitrogen content is high in relation to the FAN, the likelihood of undesirable nitrogenous compounds such as haze forming proteins being present in significant quantities is increased. In order that the brewer can avoid such problems, the maltster must therefore select suitable barley and control the malting process so as to achieve full endosperm modification without too much protein modification.
Keywords : beer brewing malt nitrogen content protein quality stability