Effect of nutrient supplementation on single cell protein production from watermelon and pineapple peels

The fast growing population of the world has led to an increased demand for protein rich food; this exerts great pressure on food and feed industries to produce sufficient quantities of protein to meet the high nutrient requirements of vulnerable populations (children and women). Single cell protein (SCP) has proven to be a sustainable approach since agricultural residues can be used for the production. In the present study, efforts were made to improve the growth support capacity of watermelon and pineapple fruit peels by submerged fermentation using Saccharomyces cerevisiae. Fruit hydrolysate media supplemented with glucose and nitrogen recorded the highest concentrations of total carbohydrate (6.6 g/L) and crude protein (20 g/L) on the 16th day of fermentation, as compared to that of the fruit hydrolysate media without supplementation which produced 3.6 g/L of total carbohydrate and 5.6 g/L of crude protein. Similarly, fruit hydrolysate media supplemented with nitrogen recorded higher content of total carbohydrate (5.4 g/L) and crude protein (20 g/L); while fruit hydrolysate media supplemented with glucose produced 5.1 g/L and 6.0 g/L of total carbohydrate and crude protein, respectively. Thus, S. cerevisiae produces higher amount of Single Cell Protein by submerged fermentation of pineapple peel hydrolysate (9.8%) as compared to watermelon peel hydrolysate (2.42%). It was also observed that, the combination of the two fruit peels produces higher SCP than watermelon but lower than pineapple fruit peels. However, supplementation with nutrients (Glucose and Ammonium sulphate) at 2% (w/v) greatly increased SCP production in all the fruit combinations. This suggest that microbial growth support capacity of fruit peels can best be improved by addition of nutrient supplements rather than combining different fruit peels. The findings in this study indicated that pineapple peels could serve as a good substrate for SCP production which is strongly influenced by glucose and ammonium sulphate supplementations.Keywords: Yeast, Single Cell Protein, Watermelon, Pineapple, Saccharomyces cerevisiae