Extraction of phenolic antioxidants from potato peel and development of a sustainable fish feed

Abstract

As the cost of the conventional feed ingredients is increasing and, simultaneously, there is also the issue of discarding waste materials generated by the agro-industries, alternative fish feeds have been explored. In the present study, extraction of the phenolic antioxidants from the potato peel waste and develop a substitute feed for aquaculture was done. Potato peels were obtained, washed, dried in an oven at 60°C, ground into a fine powder, and subjected to the extraction of the phenolic antioxidants by using 70% ethanol. Total phenolic content was estimated by the ferric chloride colorimetric assay, and antioxidant capacity was estimated by using the hydrogen peroxide scavenging method with ascorbic acid as a standard. The Fourier Transform Infrared, X-Ray Diffraction, Thermogravimetric Analysis, and proximate analysis of the potato peel powder and the fish feed were performed. A remarkable content of phenolics was noticed in potato peel extract, with a total phenolic content of 8.47 milligram Gallic Acid Equivalent per gram and excellent antioxidant performance. The antioxidant capacity increased along with the concentration of the potato peel extract. The highest was 82.5% with hydrogen peroxide scavenging activity at the highest concentration. The presence of phenolic functional groups has been evidenced with Fourier Transform Infrared. The X-Ray Diffraction results suggest that the potato peel powder and the fish feed have an amorphous nature. TGA revealed good thermal stability for formulated feed. Proximate analysis revealed 35% crude protein, 6% crude fibre, 11,5% moisture, 6.4% ash, and 5.5% fat, which are desirable characteristics for growers' phase fish feed. This investigation has proven potato peel as a cost-effective, renewable, and eco-friendly ingredient to provide phenolics, antioxidants, and other components that supplement the conventional ingredient to be used in the fish feed, and manage the waste from potato peels.