The bioconversion of various wastes such as fruit peels into some valuable products such as single-cell protein (SCP) has simultaneous potential to resolve nutritional protein deficiency worldwide. The shortage by obtaining an economical product for food and feed, as well as the mitigation of environmental pollutants to a large extent through the optimization of these residues, which serve as substrates for the production of a product with a high nutritional value. Therefore, the current study aimed to evaluate the feasibility of using fruit peels such as orange peel and pomegranate and their mixture through chemical treatment concentrations of dilute hydrochloric acid as well as thermal treatment by autoclave to obtain the highest concentration of sugars needed for yeast growth and the evaluation of biomass yields as a single-cell protein (SCP). The results showed that orange and pomegranate peels treated with different concentrations of 10, 20 and 30% hydrochloric acid had the highest yield of reducing sugars )4.89g/100g peel) obtained from orange peels treated with 10% acid concentration. After that, a comparison was made between the treatment with the best concentration of acid (HCl 10%) and the thermal treatment by autoclaving for orange peels, pomegranate peels and a mixture of them, so the treatment with acid (HCl 10%) for the mixture had the highest concentration of reducing sugars, followed by orange peels (5.90 and 4.87g/100g peels) respectively. But it was found that this treatment affects the growth of Saccharomyces cerevisiae later compared to the thermal treatment. After that, the media were prepared from orange peels and pomegranate peels, mixed with acid (HCl 10%) and heat treatment, and salts were added to one of them and the other without salts. The results were in favor of the thermal treatment. The orange peels thermal treated without salts gave the largest amount of protein, followed by the mixture without salts, then the mixture with salts that were thermal treated (9.39, 8.107 and 8.02 g/L) respectively.