Kinetic of degradation of ascorbic acid in passion fruit juice

Abstract

It was evaluated the kinetic degradation of the ascorbic acid in passion fruit juice "maracuya" (Passiflora edulis f. Flavicarpa) fresh and pasteurized at different storing temperatures (0 degrees C, 10 degrees C, 25 degrees C, 40 degrees C, 60 degrees C). The juice was characterized in terms of pH, titration acidity, total soluble solids, degrees Brix/acidity relation - and total sugars. The passion fruit juice samples, fresh and pasteurized, were stored at 0 degrees C, 10 degrees C during 60 and 15 days respectively. Samples of fresh passion fruit juice were also taken and stored at 25 degrees C, 40 degrees C for 10 hours and at 60 degrees C for 2,5 hours. The kinetic of acid ascorbic degradation in fresh and pasteurized passion fruit juice has a behavior of zero order for temperatures of 0 degrees C 25 degrees C, 40 degrees C and 60 degrees C. A first order kinetic was obtained for fresco refrigerated passion fruit juice at a temperature of 10 degrees C, where as a second order kinetic was obtained for the pasteurized juice at the same temperature. The activation energy estimated from Arrhenius equation was 92.168 J/mol and the frequency factor was 1.583 x 10(13) min(-1) in fresh passion fruit juice for zero order reactions at 0 degrees C, 25 degrees C, 40 degrees C and 60 degrees C temperatures.