Analysis of the impact of fermentation tank size on Delta beer

Details

Supervisors

Sonia Collin

Faculty

Faculté des bioingénieurs

Degree label

Master de spécialisation en génie brassicole

Abstract

Brussels Beer Project is a Brussels-based brewery, specialized in craft beers. Founded in 2013, the brewery based in Dansaert has rapidly become too small to produce all of their beers. In 2021, a new brewery, called Port Sud, will be built, enabling BBP to progressively brew all of their beers themselves. A transition from Anders brewery to Port Sud is therefore a crucial point of the project, as the beers need to remain similar while both breweries are different. This thesis project will focus on the impact of the fermentation tank size on the aromatic profile of the Delta, BBP’s most sold beer. Fermentation tanks used for Delta at Anders are 120 hL tanks while 240 hL tanks will be used at Port Sud. Literature review has taught us that higher aspect-ratio fermenters lead to higher agitation rate due to CO2 bubbles and hence higher suspended yeast count. This will imply higher fermentation rates, increased yeast growth, greater attenuation of wort, reduced beer nitrogen, increased concentration of higher alcohol, lower beer pH, and less ester formation. Higher aspect-ratio fermenters also lead to higher hydrostatic pressure but we do not expect any deleterious effect from that given the relatively low pressures that are easily bearable by Saccharomyces cerevisiae. Experiments in two fermentation tanks from 80 and 120 hL have confirmed some of these hypothesis. Regarding the fermentation dynamics, a slightly greater attenuation was observed in the 120 hL tank. Regarding volatiles, globally we did not observe many differences between the two batches of Delta. The most noticeable difference was the concentration of esters which was higher in the 80 hL tank, as expected. Differences in levels of terpenes and thiols were also observed but are not likely to be caused by the difference in tank size. However our experiments have demonstrated the importance of cold storage to preserve important hop-related compounds.