Torulaspora

Torulaspora is a genus of yeasts in the family Saccharomycetaceae, within the phylum Ascomycota. Members are saccharomycetous yeasts that are widely distributed in nature and commonly isolated from fruits, dairy products, and spontaneous fermentations. They are non-pathogenic and primarily fermentative, and they are of interest for their use in mixed-culture fermentations alongside Saccharomyces cerevisiae to influence aroma and texture.

Taxonomy and notable species: The best-known species is Torulaspora delbrueckii, extensively studied for wine fermentation and other food fermentations. Other described species include Torulaspora pretoriensis, Torulaspora globosa, and Torulaspora microellipsoidea. Species differ in physiology and aroma production, which underpins their selective use in industry and research.

Ecology and physiology: Torulaspora species can grow over a range of sugar concentrations and conditions typical of fruit and fermentation environments. They reproduce asexually by budding and can form asci with ascospores under certain circumstances. They are generally considered safe for food use and are studied for traits such as glycerol production, aroma compound formation, and stress tolerance.

Applications and significance: In oenology, non-Saccharomyces yeasts like Torulaspora delbrueckii are used in sequential or co-fermentations with S. cerevisiae to diversify aroma profiles, improve mouthfeel, and influence fermentation kinetics. They may alter ethanol yield and acetaldehyde formation depending on conditions. Beyond wine, Torulaspora species are explored in other fermented foods and beverages and in research settings to understand yeast metabolism and aroma biosynthesis.

Genetics and research: Genome sequencing and comparative studies of Torulaspora species advance knowledge of sugar transport, metabolism, and aroma pathways, informing selection and application in fermentation processes.