Effect of storage on antioxidant activity of freeze-dried potato peels

A study was undertaken with the objective of evaluating the storage stability of the polyphenols and the antioxidant activity in the peel from two varieties of potatoes, Penta and Marcy, grown in Ontario, Canada. Samples were stored at −20, 4 and 25 °C for 0, 2, 4 and 8 weeks. Peel from Penta variety contained higher levels of total polyphenolic compounds, 2.4 mg/g of peel d.w. compare to Marcy, 1.14 mg/g of peel d.w. Chlorogenic and caffeic acids were the major polyphenolic compounds present in both verities. Levels of polyphenolic compounds in the peel were influenced by storage temperature with maximum loss observed at 25 °C. Storage time caused a decline in the levels of polyphenolic compounds up to 4 weeks at all temperatures followed by a significant increase at the end of week 8. There was a parallel increase in the antioxidant activity of the peel samples during storage and until the end of 8 weeks of storage. At all temperatures of storage, there was a significant relationship (r = 0.43, P ≤ 0.05) between the amount of polyphenolic compound in the peel samples and their antioxidant capacity. Results suggest potato peel as a valuable source of polyphenolic compounds requiring proper storage condition to maintain their antioxidant properties.