Subcritical water extraction of phenolic compounds from potato peel

Potato peel, a waste generated from potato processing, is a disposal problem. But, potato peel is a good source of functional ingredients such as phenolic compounds. This study investigated the extraction of eight phenolic compounds (Gallic acid, GAC; Chlorogenic acid, CGA; Caffeic acid, CFA; Protocatechuic acid, PCA; Syringic acid, SGA; p-hydroxyl benzoic acid, PBA; Ferulic acid, FRA and Coumaric acid, CMA) from potato peel using subcritical water. Experiments were performed in a batch stainless steel reactor at 6 MPa, 2 mL/min and temperatures ranging from 100 to 240 °C at residence time of 30 to 120 min. High recoveries of phenolic compounds (81.83 mg/100 g; wet basis wb) were obtained at 180 °C and extraction time of 30 min compared to 3 h extraction with methanol (46.59 mg/100 g wb). CGA (14.59 mg/100 g wb) and GAC (29.56 mg/100 g wb) were the main phenolic compounds obtained from potato peel at 180 °C. Subcritical water at 160 to 180 °C, 6 MPa and 60 min might be a good substitute to organic solvents such as methanol and ethanol to obtain phenolic compounds from potato peel.