Immobilization of lager yeast by hydrocolloids as supporting matrix for improving fermentation performance of high gravity brewing

Abstract

The objective of this study was to investigate the effects of six kinds of hydrocolloids supplementations, namely κ-carrageenan, gellan gum, pectin, gum ghatti, karaya, and guar gum as the supporting matrix, on the fermentation kinetics of lager yeast during high gravity beer fermentation. Results showed that hydrocolloids supplementations significantly accelerated fermentation and resulted in higher consumption of reducing sugar and free amino nitrogen, and higher production of ethanol and flavor volatiles. Compared to the control, wort fermentability and ethanol production were increased by 19.3% and 25.0%, respectively, by κ-carrageenan supplementation. Furthermore, volatile compounds formation and aroma complexity (25 new volatile compounds) of green beers were improved by hydrocolloids supplementation, and the reduction in acetic acid and acetaldehyde contents was observed, which suggested favorable flavor characteristics. Results of SEM images revealed that hydrocolloids supplementation induced the immobilization of yeast cells through flocculation, providing a protective effect on the physiological characterization of lager yeast during high gravity brewing.