The Improvement of Reserve Polysaccharide Glycogen Level and Other Quality Parameters of S. cerevisiae Brewing Dry Yeasts by Their Rehydration in Water, Treated with Low-Temperature, Low-Pressure Glow Plasma (LPGP)

Aneta Pater,Marek Zdaniewicz,Paweł Satora,Karen Khachatryan,Małgorzata Makarewicz

doi:10.3390/app12062909

Abstract

The increasing popularity of active dry yeast arises from its properties, such as ease of storage, and simplicity of preparation and dosing. Herein, we elaborate on the effect of plasma-treated water (PTW) under air atmosphere (PTWAir) and nitrogen (PTWN) on the improvement of the reserve polysaccharide glycogen level and other quality parameters of S. cerevisiae brewing dry yeast in comparison with the non plasma-treated water (CW). For this purpose, strains of top-fermenting (S. cerevisiae T58 (poor quality), S33 (poor quality)) and bottom-fermenting (S. pastorianus W30/70 (poor quality)) yeast stored one year after opening and S. cerevisiae US-05 (fresh strain) were selected to examine the influence of PTWs toward the quality parameters of yeast biomass after the rehydration and fermentation process. The obtained results showed that in the case of poor quality yeast strains, PTWAir increased glycogen content after the rehydration and fermentation process, which was a favorable trend. A similar increase was observed for the trehalose content. Results showed that PTWN significantly reduced the number of yeast cells in ale strains and the viability of all analyzed samples. The lowest viability was observed in Sc S33 strain for PTWAir (41.99%), PTWN (18.6%) and CW (22.86%). PTWAir did not contribute to reducing the analyzed parameter; in particular, the results of Sc T58 yeast strain’s viability are shown: PTWAir (58.83%), PTWN (32.28%) and CW (43.56%). The obtained results suggest that rehydration by PTWN of dry yeast with a weakened condition is not recommended for both qualitative and cost-related reasons, while PTWAir significantly contributed to the improvement of some yeast parameters after rehydration and fermentation (higher glycogen and trehalose content).

Highlights

Introduction iationsIn the brewing industry, the most frequently used species of yeast are Saccharomyces cerevisiae and S. pastorianus [1]
For the results presented in the article, the most similar result was obtained for the fresh quality yeast strain of Sc US-05 for the samples after rehydration in the presence of Plasma-Treated Water under Air Atmosphere (PTWAir) (83.3%) and CW (84.5%)
The current research reports the influence of plasma-treated water obtained in different atmospheres on the rehydration and technological parameters of brewing yeast—top- (S. cerevisiae) and bottom-fermenting (S. pastorianus)

Summary

Introduction

The most frequently used species of yeast are Saccharomyces cerevisiae and S. pastorianus [1]. It is possible to ensure the appropriate quality of yeast biomass thanks to the laboratory facilities. In the case of smaller breweries, the number of propagation stations is constantly growing. Brewer’s yeast can be used for subsequent fermentation cycles [2]. Craft breweries that do not have propagation stations use dried yeast. Dried yeast has similar characteristics to fresh yeast in terms of aroma compound formation, fermentation rate and attenuation [3]

Methods

Results

Conclusion