Future production of yeast biomass for sustainable proteins: a critical review

Yeast biomass has untapped potential as a sustainable source of nutritional protein. To realise this, current production capacity and the demand for yeast-based products in food applications must be increased. This review explores the possibility of increasing yeast supply using low-cost and sustainable substrates such as lignocellulosic sugars, starch hydrolysates and waste lactose, and by utilising the waste yeast biomass that will be generated from future recombinant protein production. Candidate yeast strains and processes for producing biomass from these substrates are reviewed in relation to production efficiency and product functionality. The opportunity to lower production costs and control yeast cell properties using continuous cultivation is highlighted. Current knowledge of how yeast diversity, metabolism and physiology are influenced by growth conditions is brought together to understand how yeast biomass can be produced with desirable functional properties. In particular, this review provides insights into how the variety and adaptability of yeast can make it possible to adjust attributes such as protein and cell wall composition through strain selection and controlled production. Major gaps are identified as targets for future research, in particular understanding the functional properties of non-Saccharomyces yeast biomass that could be produced from lignocellulosic sugars, lactose and precision fermentation. Specific, controlled studies of yeast biomass functionality in relation to species and growth are now needed to help expand the scale of production and associated environmental benefits of nutritional yeast.