Effect of drying and milling industrial potato peel for recovering phenolic and antioxidant compounds: Optimization process and economic evaluation

Abstract

Currently, industrial potato peel (PP) represents a cost to the industry and a potential burden on the environment. This study aims to discuss the need to dry and mill PP before extracting phenolic and antioxidant compounds, aiming to achieve the most profitable strategy to valorize the residue without introducing irrelevant and expensive processes. A design of experiments and a simplified economic evaluation were used to compare the two scenarios: PP without pre-treatment and after drying and milling (PPt). A central composite design with two factors (ethanol concentration and solid/liquid ratio) was performed aiming to maximize two response variables (concentration of phenolic compounds in the extract and antioxidant activity). A maximum of 46.9 ± 2.6 mg GAE/g dry extract and an IC50 of 900 mg/L was achieved by extracting PPt with 50 % ethanol. For PP extraction, only ethanol concentration was revealed to be important, achieving an extract with 22.8 ± 0.8 mg GAE/g dry extract and an IC50 of 900 mg/L with 60 % ethanol. The economic analysis showed that the reduced extraction yield and the increment in ethanol used for extracting potato peel without pre-treatment significantly affected the operating costs. A more economic scenario is achieved by drying and milling PP.