Phenolics in Potato Peels: Extraction and Utilization as Natural Antioxidants

The total phenolics content of potato peel extracts of five different solvents (water, ethanol, hexane, methanol and acetone) and two solvent extraction methods (Solvent and ultrasound-assisted) were studied. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents. Antioxidant activity of methanolic extracts was determined by using the Oven (63°C) and Rancimat (90,120,150°C) methods on refined soybean oil and compared with the effects of synthetic antioxidants ( BHA, BHT and TBHQ). Peroxide values and 2-thiobarbituric acid values were used to assess lipid peroxidation. The greatest amount of extract was obtained with water but the greatest amounts of phenolic acids resulted when potato peels was extracted with methanol. Using ultrasound improved the total phenolic compounds of the potato peel extract. After 16 days storage at 63°C, 5.00g of soybean oil containing either the methanolic extract (800, 1600 ppm) or BHA (200 ppm) and BHT (200 ppm) reached peroxide values (PV) of 37.35, 24.65, 33.20 and 28.88 meq/kg respectively. Also the Rancimat method revealed that TBHQ was the best antioxidant but potato peel extract was as good as BHA and BHT.