Optimization of Antioxidant Compounds Extraction from Fruit By-Products: Apple Pomace, Orange and Banana Peel

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The aim of this research was to optimize, by response surface methodology, antioxidant compounds extraction from apple pomace, orange and banana peel. The extracts were obtained at different temperatures and times. All by-products show a good content of vitamin C (12–102 mg of ascorbic acid/100 g dw), flavonoids (455–756 mg of catechin/100 g dw), phenolic compounds (227–689 mg of gallic acid equivalent/100 g dw), antioxidant capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH; 454–1,040 mg of Trolox/100 g dw) and ferric-reducing antioxidant power (FRAP; 4–32 mM Fe2+/100 g dw) assays. Polynomial models obtained from each by-product showed a good fitting (0.81–0.97). Temperatures of 41–60C promote the major extraction of bioactive compounds and antioxidant capacity from apple pomace. In orange peel, the optimum condition for vitamin C extraction was 20C (0.5 h); flavonoids, total phenols and antioxidant capacity (DPPH) were mostly extracted at 60C. In banana peel, the optimization indicates that major flavonoid concentration and antioxidant capacity (DPPH and FRAP assays) were at 60C (0.5 h). Practical Applications By-products are a good source of bioactive compounds that could be used to obtain products with added value; in this sense, the optimization of extraction of bioactive compounds with antioxidant capacity may be an important step in order to obtain the major concentration of antioxidant compounds with the less use of energy and cost. Therefore, the information presented in this study may be a good tool to apply in the industrial extraction of bioactive compounds from apple pomace, orange and banana peel.