Balancing the Brew: Fermentatior Dynamics of Saccharomyces and Combined Yeast Cultures

Yeast, a eukaryotic unicellular microorganism essential for fermentation, is a low-cost raw material for alcoholic products such as wine, beer, and spirits and has more than 700 identified species (Sandefur, 1998).

- Athira R S¹, Madhumitha M¹, Mathangi G, Baskaran N, Vignesh S¹

1. Introduction

The industrial importance Saccharomyces species have been adequately defined, whereas many others are barely characterized (Sandefur, 1998). Yeast fermentation of various plant carbohydrates is one of our earliest human inventions, which started in the Neolithic era (Dashko et al., 2014). Fermentation is a vital metabolic process in distilleries, where yeast produces alcohol or acid from starch or sugar. It's a natural process used for thousands of years in making alcoholic beverages, bread, and byproducts (Maicas, 2020a).

The baker's yeast Saccharomyces cerevisiae is utilized extensively to produce ethanol for both industrial and commercial purposes because it has the ability to convert sugars to ethanol and carbon dioxide in both anaerobic and aerobic conditions (Dashko et al., 2014). Under aerobic conditions, respiration is possible with oxygen as the final electron acceptor, but S. cerevisiae exhibits alcoholic fermentation until the sugar level reaches a low level, a phenomenon known as the Crabtree effect (Dashko et al., 2014). Fermentation was not well understood in ancient times, but through experimentation, people discovered its potential, leading to the rich and diverse array of alcoholic beverages known today.

2. Fast facts about yeast

Over 1,500 species of yeasts have been described, and this number is rapidly increasing due to advances in molecular and genomic sequencing techniques (Kurtzman et al., 2011). Yeasts carry out different types of fermentation based on species and conditions, including alcoholic fermentation by Saccharomyces cerevisiae, lactic acid production by Candida kefyr, mixed acid fermentation under stress in non-Saccharomyces strains, glycerol production for stress protection, and volatile aroma compound formation by wine yeasts like Torulaspora delbrueckii (Maicas, 2020b).

2.1. Why Saccharomyces cerevisiae?