Vitamins in brewing: effects of post-fermentation treatments and exposure and maturation on the thiamine and riboflavin vitamer content of beer

Post-fermentation processes and maturation are important steps in beer production as they help to shape the organoleptic properties and stabilize the final product. Brewers can use a variety of processing aids (e.g. isinglass, PVPP, etc.) and processes (e.g. pasteurization, bottle conditioning, etc.) to achieve a desired final product with a desirable shelf life; however, these processes can have detrimental effects on the vitamin content of the beer. This research found that heat treatments have a marked influence on the decrease in the thiamine diphosphate vitamer, while PVPP and silica treatments have a greater influence on the decrease in riboflavin vitamers. Refrigeration, filtration or centrifugation have no, or only very limited, influence on thiamine or riboflavin vitamers, while application of isinglass, bentonite, tannic acid and SO2 causes a decrease in both thiamine and riboflavin vitamers. Storage of beer at refrigerated temperatures appears to provide protection against significant degradation of both thiamine and riboflavin vitamers; however, storage of filtered beer at elevated temperatures shows a decrease in thiamine diphosphate and riboflavin. Storage of bottle-conditioned beer at elevated temperatures shows a marked decrease in yeast viability, accompanied by a decrease in thiamine diphosphate and free riboflavin, and a marked increase in free thiamine. These findings provide an insight into the reason why there is a significant variation in the vitamer content of beers, even within a single beer style. Copyright © 2016 The Institute of Brewing & Distilling