Utilization of Food Industries Wastes for The Production of Single Cell Protein by Yeasts

To study the potential of producing single cell protein (SCP) from waste materials to decrease the protein gap and to reduce the environmental pollution, five yeast strains (Candida blankii, Candida rugosa, Pichia anomala, Kluyveromyces lactis and Rhodotorula glutinis) were used. The results of growth of the tested strains on four types of food industries wastes (cheese whey, orange peel, beet pulp and rice husk) as indicated by their protein and nucleic acids content, showed that Kluyveromyces lactis and Candida rugosa grew well on whey, while Candida blankii, Rhodotorula glutinis and Pichia anomala grew better in orange peel. The highest value of protein content was obtained with Kluyveromyces lactis on whey (6.78 g/l) followed by Candida blankii on orange peel (6.01 g/l). On the other hand, the lowest values of protein content were found when rice husk and beet pulp were used for growth of these strains. Nucleic acids content followed the same trend of protein content and the highest value was obtained with Kluyveromyces lactis on whey (1.05 g/l) and then Candida blankii on orange peel (0.88 g/l), whereas rice husk and beet pulp gave the lowest values. Heat shock at 64 C for 20 min caused a reduction in nucleic acid contents ranged from 65.2 to 88.8%, whereas the reduction by ribonuclease (RNase) enzyme reached over 99.0 %. It is concluded that SCP could be produced from some food industries wastes providing the appropriate strain of yeast is used. Nucleic acids content can be reduced to the required limit.