Single Cell Proteins production from food processing effluents and digestate

The increase in human population determines a higher proteins request to sustain the feed demand for animals and aquaculture. Single Cell Proteins (SCPs) consist of mixed protein from pure and mixed culture of bacteria, fungi, algae, and yeast, which are grown and harvested to accomplish the food requirement of human and animals. This work investigated the production of Saccharomyces cerevisiae to be used as SCPs for animal feeding. The effluent of candies production process, rich in sugars, about 40 g/L, and agricultural digestate rich in nitrogen and other macro and micronutrients, were used for the yeast's growth. Preliminary batch tests demonstrated that aerobic conditions optimized the biomass growth. Then, continuous aerobic tests were conducted at different dilution rates. The dilution rate of 0.50 d(-1), corresponding to a hydraulic retention time of 2 days, optimized both the biomass productivity of 0.25 g/L per day and the protein content of 28% w/w. The analysis of the aminoacidic profile demonstrated that obtained SCPs could be used as an integrator of feed for fish and monogastric animals. On the contrary, they were not suitable for pet feed as all the amino acids concentrations were lower than required standards. These results suggested that anaerobic digesters in the agricultural sector can be transformed into small biorefineries for microbial protein production.

Automated summary

The increase in human population has led to a higher demand for protein, and Single Cell Proteins (SCPs) are a mixed protein source that can meet the food needs of animals and humans. This study explored the production of Saccharomyces cerevisiae as SCPs for animal feeding, using effluent from candy production and agricultural digestate as growth mediums. The results showed that aerobic conditions and a dilution rate of 0.50 d(-1) optimized both biomass productivity and protein content. The obtained SCPs were suitable as a feed supplement for fish and monogastric animals, but not for pets due to lower amino acid concentrations.