Production of alcohol-free beer with elevated amounts of flavouring compounds using lager yeast mutants

Abstract

Arrested or limited fermentation process is a widespread method used for production of alcohol-free beer (AFB). However, it usually leads to worty off-flavour and a lack of pleasant fruity flavour/aroma. The aim of this study was to isolate spontaneous mutants of Saccharomyces pastorianus strain 2 resistant to 5,5,5-trifluoro-DL-leucine, since the resistance is related to overproduction of flavour active isoamyl alcohol (IAAL) and isoamyl acetate (IAAC). The mutants were the subject of selection during series of screening tests aimed at selecting the best producer of target compounds (IAAL and IAAC). Subsequently, the overproduction stability of the selected mutant strain was verified in four consecutive fermentations of AFBs. A higher pitching rate and increased fermentation temperature did not result in an overall improvement in the production of the target compounds. Sensory analysis proved the flavouring effect of the spontaneous lager yeast mutant on the AFB produced by arrested fermentation.

Gravity-Driven Adaptive Evolution of an Industrial Brewer’s Yeast Strain towards a Snowflake Phenotype in a 3D-Printed Mini Tower Fermentor

“…A number of investigations have demonstrated the feasibility of directing evolution in natural Saccharomyces pastorianus hybrid stains in order to create variant strains with improved functional properties [6]. Such investigations have focused on adaptation to very high-gravity brewing conditions [7][8][9], associated stresses (such as osmotic stress and ethanol toxicity) [10,11], or the modification of the production of flavour compounds [12]. ALE has also been utilised to enhance the fermentation rate of S. cerevisiae with decreased formation of acetate and greater production of aroma compounds [13,14].…”

Volatile Compound Profiling in Commercial Lager Regular Beers and Derived Alcohol-Free Beers After Dealcoholization by Vacuum Distillation

“…High losses of volatile compounds have been reported during the lab-scale vacuum dealcoholization process and also when commercial regular beers and their related nonalcoholic beers were compared (Zürcher et al 2005;Montanari et al 2009;Lehnert et al 2009;Brányik et al 2012;Strejc et al 2013). In this study, the major losses were found over the initial period of the dealcoholization experiments, and, hence, although the system is only nearly comparable to the industrial scale ones, our results suggest that the volatile compound behavior is likely to be also comparable.…”

Brewer’s yeast in controlled and uncontrolled fermentations, with a focus on novel, nonconventional, and superior strains

“…There are a number of examples of this approach, leading to the design of S. pastorianus (123,124) or S. cerevisiae strains (125) with enhanced performances. Examples also include the design of S. pastorianus strains for improved growth under hyperosmotic conditions (126) or with improved production of flavor compounds (127,128). Finally, a possible solution to overcome consumer distaste towards GMO could be the application of self-cloning yeasts because only homolog DNA or DNA from a closely related organism are inserted or modified (135).…”