Grain Thin Stillage Protein Utilization: A Review

Ethanol production from grains produces wet grain and thin stillage (TS) as major coproducts. The grain fuel ethanol industry is massive, producing 58 billion L per year in the USA alone, and TS production is four to five times this volume. In short, through its coproducts TS and distiller's grains, the ethanol industry is a major supplier of inexpensive protein. However, obtaining this protein can be costly. In spite of its high water content, TS is typically concentrated by evaporation and then sold as distiller's solubles, or combined with wet grain and dried for use as an animal feed ingredient called “distillers’ dried grains with solubles”. The processes used for protein concentration and TS clarification are reviewed, including the addition of clarifying agents, centrifugation, dissolved air and anoxic gas flotation, filtration, size exclusion, and biorefinery processes. Biorefinery processes are being developed that will lower the energy inputs required for evaporation while greatly improving protein concentration. The protein concentrates could potentially be used in higher‐quality animal feed or even in food products.