Electrostatic Fermentation: Molecular Response Insights for Tailored Beer Production

Abstract

Electrostatic fermentation avoids the cellular redox imbalance of traditional fermentation, but knowledge gaps exist. This study explores the impact of electrostatic fermentation on the growth, volatile profile, and genetic response of Saccharomyces pastorianus Saflager S-23. The applied voltage (15 and 30 V) in the electrostatic fermentation system increased the growth and substrate utilization of S. pastorianus while decreasing ethanol production. The aromas typically associated with traditional fermentation, such as alcoholic, grape, apple, and sweet notes, were diminished, while aromas like roses, fruits, flowers, and bananas were augmented in electrostatic fermentation. RNA-seq analysis revealed upregulation of genes involved in cell wall structure, oxidoreductase activity, and iron ion binding, while genes associated with protein synthesis, growth control, homeostasis, and membrane function were downregulated under the influence of applied voltage. The electrostatic fermentation system modulates genetic responses and metabolic pathways in yeast, rendering it a promising method for tailored beer production. Demonstrating feasibility under industrial-scale and realistic conditions is crucial for advancing towards commercialization.

Keywords: RNA-seq; Saccharomyces pastorianus; electrostatic fermentation; low-alcohol beer; volatile profile.

Figure 1

The electrostatic fermentation cell consisted of a plastic bottle with a graphite electrode located at the center of the lid and an AWG 24 enameled copper wire coiled with 300 loops around the bottle. Both the electrode and the copper wire were connected to a power supply.

Figure 2

Growth and ethanol parameters of Saccharomyces pastorianus Saflager S-23 under the electrostatic fermentation system at 15 V (gray), 30 V (white) and traditional fermentation (TF) in black. Specific growth rate (A), ethanol yield (B), specific substrate consumption (C), and specific ethanol production (D). Different letters indicate statistical significance (p < 0.05). Results are reported as the mean ± standard deviation (n = 3).

Figure 3

Volatile compound identification on the wort at 60 h in traditional fermentation (TF), 15 V, and 30 V (A). Aroma profile of traditional fermentation (B), and in the electrostatic fermentation system applying 15 V (C) and 30 V (D). Lighter colors correspond to lower concentrations, while darker colors correspond to higher concentrations.

Figure 4

Gene ontology enrichment comparison of differentially expressed genes for biological process (A), molecular functions (B), and cellular components (C) in the electrostatic fermentation system applying 15 V and 30 V compared to traditional fermentation (p < 0.05 and fold change >2).