Use of secondary raw materials of the agro-industrial complex in feed production technologies

Abstract

The study aimed to assess the bioconversion potential of secondary raw materials (SRM) in the agro-industrial complex and develop a system of scientifically valid parameters for their application in the production of feed products enriched with carotenoids and microbial proteins. The study subjects were wheat bran, lingonberry cake, corn cobs, and malt; and strains of carotenoid yeasts of the genera Rhodosporidium and Rhodotorula from the culture collection of the All-Russian Research Institute of Food Biotechnology. The most promising yeast strain was Rhodosporidium species SK-111-15, which was characterised by the highest biomass accumulation (6.25±0.24 g) and productivity (55.5±2.22 g/dm3), lower humidity level (77.8±3.11%), low dry matter content in the centrate (4.30±0.17%), the highest carotene synthesis (1.21±0.05 mg/100 cm3) and microbial protein content (49.83±1.99% of absolutely dry matter). Upon completion of the cultivation of carotenoid yeast on food production waste, the fermentation medium with corn cobs was distinguished by the best biochemical parameters. The concentration of microbial biomass reached 45.21± 1.79 g, which was almost 12 times higher than the value of this indicator in the control (3.83±0.15 g). The residual content of dry matter and carbohydrates in the centrate in this variant was 0.6±0.02% and 0.01% on an absolutely dry matter (a.d.m.), respectively. At the same time, a high concentration of carotenoids (1.65±0.06 mg/100 cm3) and a specific growth rate (0.07 h-1, which is 3.5 times higher than the control) were recorded. The content of crude protein (31.50±1.26% on an a.d.m) differed insignificantly from the control (31.80±1.27% on an a.d.m). Based on the research results, a medium containing corn cobs was selected for further development of feed production technology.