Kinetics of Polyphenol Losses and Antioxidant Activity of Extracts from Olive Cake During Evaporation

Polyphenols were extracted from olive cake and then concentrated at 50, 75, and 100°C by the evaporation of extract. Antioxidant activity of total polyphenols in olive cake extract decreased while the concentration of total polyphenols increased during the evaporation of extract at 100°C, but concentration of polyphenols slightly increased while antioxidant activity did not change at 75°C. These results showed that antioxidant activity is not related and estimated with the amount of total polyphenols. Reaction rate for the loss of polyphenols is found zero order at 50 and 75°C with r2 of 0.99 and at 100°C with r2 of 0.85. Low r2 value at 100°C requires the consideration of a different kinetic model to predict the losses of polyhenols at a high temperature of 100°C.