Abstract

High gravity brewing is a perspective technique for increasing brewing capacity without significant capital expenditure. In Vietnam, high gravity brewing has been carried out in some breweries, the specific gravity of wort is up to 16°Plato (Pt). In this paper, fermentation of the 16-22°Pt wort was examined. The obtained results showed that the higher the specific gravity of wort, the longer the fermentation time and the higher the residual substrate content in the green beer. The principal reason was due to high ratio of C/N content in wort. Then some nitrogen sources were alternatively added to the 22°Pt wort. It was showed that the fermentation was significantly accelerated and the alcohol content in the green beer increased. Yeast extract was considered as a suitable nitrogen source for supplementation in high gravity brewing. For the 22°Pt wort, the optimal content of supplementing yeast extract is 90mgN/litre.