Wort Trub Content and its Effects on Fermentation and Beer Flavor

Pilot-scale fermentations were conducted to determine the impact of various trub levels on fermentation kinetics and beer flavor. Trub content of the worts ranged from 0.00 to 2.66% (v/v). Clarified worts were produced either by filtration or by whirlpool treatment. Worts with high trub content were produced by omitting clarification treatment altogether, or by clarifying wort and then adding predetermined amounts of trub to the fermentor during fill. Results indicated that trub stimulated yeast activity, and subsequently, the rate of fermentation. In addition, elevated trub levels depressed the formation of esters and slightly increased production of fusel alcohol. Flavor analyses of the finished product demonstrated a preference for beers produced from clarified worts. The relationship between trub and fermentation kinetics appeared to be related to high lipid and zinc contents in the trub, which may have contributed important growth factors to the yeast. These findings demonstrate the importance of utilizing a wort processing technique that achieves an optimum and consistent trub level in production wort.