Fermentation studies of wort made using malt and different adjuncts : Rice and maltose syrup

Fermentation studies of brews made using 30% rice adjunct and 70% malt or 30% maltose syrup adjunct and 70% malt showed that mash made using rice adjunct and malt contained more total soluble nitrogen (TSN) and free amino nitrogen (FAN) and released more peptides into the wort than mash made using maltose syrup adjunct and malt. The rice adjunct mash also contained peptides that were more readily assimilated by yeast during fermentation than did the maltose syrup adjunct mash. Both types of mash, however, produced different levels of FAN products (>140 mg/L) required for yeast fermentation. Although the mashes produced different levels of FAN products, a similar amount of FAN was taken up by yeast in both fermentations, after which, excess FAN was carried over into the beer. The high levels of TSN and FAN products found in the beers brewed in the pilot plant seemed to be a general characteristic of beer, because different levels of TSN and FAN products were also found in commercially brewed beers that were analyzed in a different experiment. The results suggest that FAN levels >150 mg/L in the wort during fermentation might not be a prerequisite to achieve optimal yeast performance during the fermentation of wort.