Production of single cell protein by fungi from different food wastes

Abstract

Single-cell protein (SCP) which is derived from agricultural waste has recently drawn increased interest as a substitute source of protein to improve both human and animal nutrition. In this study, pineapple, orange, banana, sugarcane, and garlic wastes were prepared as substrates for SCP production using fungi under a liquid fermentation system. The fermentation conditions (temperature, pH, and nitrogen sources) of the most promising fungal isolates were optimized for maximum SCP production. Results obtained showed that Aspergillus niger with pineapple waste after 10 days gave the highest protein content (9.79 ± 0.11 g/L), followed by Penicillium citrinum with orange waste after 8 days (9.41 ± 0.15 g/L) and Penicillium crustosum with banana waste after 6 days (7.75 ± 0.11 g/L).The optimum fermentation temperature, pH value, and nitrogen source for SCP production were recorded at 30 °C, pH 4.3, and ammonium sulphate with Aspergillus niger; at 30 °C, pH 5.0, and ammonium sulphate with Penicillium citrinum; and at 20 °C, pH 5.0, and ammonium sulphate with Penicillium crustosum. Based on proximate analysis of SCP produced, fat content ranged from 2.74 ± 0.08∼10.73 ± 0.1%, fibers from 4.8 ± 0.18∼9.45 ± 0.15%, carbohydrates from 14.1 ± 0.06∼20.81 ± 0.06%, ash from 4.05 ± 0.05∼16.1 ± 0.2%, total phenols 0.14 ± 0.03∼0.64 ± 0.04%, and total flavonoids 0.09 ± 0.01∼0.55 ± 0.15%. The amino acid profile of SCP showed that all essential amino acids were present in significant amounts. This study recorded some fungal species as SCP producers for the first time and provided a significant amount of protein. Briefly, fungal SCP is a great protein source and other essential nutrients that may be used in food products. Graphical Abstract