Influence of Lauter Turbidity on Wort Composition, Fermentation Performance and Beer Quality in Large-Scale Trials

Different lauter turbidities (standard 43 EBC vs. turbid 82 EBC on average) were obtained by variation of the lauter procedure, particularly deep raking, in this study. The resulting worts were used for repitching the respective yeast into six subsequent fermentation cycles. The resulting beers were investigated in terms of flavour quality, flavour stability, non-biological stability and foam stability. Worts gained from turbid lautering showed very similar analytical data compared to the controls (except for a slight but significant increase in linoleic acid). There was an improvement in fermentation performance in terms of a pH decrease and a decrease in extract. The resulting beers were quite similar, and the staling indicators increased slightly, but not significantly, due to turbid lautering. Both types of beer were evaluated on tasting as being of a high flavour quality and neither a professional panel nor a non-professional (customer) panel was able to distinguish the difference, between standard and turbid lautering, in terms of fresh and forced aged beers. Due to turbid lautering the non-biological stability appeared to be slightly, but not significantly, decreased while on the other hand the foam stability was significantly improved due to turbid lautering. In conclusion, fermentation performance may be improved by more turbid lautering, and the negative consequences often reported for the resulting beers appear to be overestimated, since the quality parameters of the final beers had not deteriorated significantly.