Evaluation of enzymatic pretreatment of passion fruit juice

Abstract

Yellow passion fruit juice is enjoyed worldwide due to its pleasant unique aroma and flavor. However, conventional stabilization processes induce general losses in the juice's original aroma and flavor. Membrane-based techniques are an alternative to obtain clarified and sterilized passion fruit juices. However, the high pectin and starch content makes the achievement of enhanced flow rates of permeate only possible after an enzymatic liquefaction of the juice. The scope of this work was to find the best condition for the enzymatic treatment of passion fruit in order to minimize the viscosity before the micro filtration process. The first step consisted on comparing the reduction of viscosity of the juice using different available commercial enzymes with pectinolityc, cellulase, and amylase activities. After the selection of the best enzyme-preparation, investigations were carried out in order to identify which were the significant variables for the enzymatic treatment. The studied variables were incubation time (from 30 to 120 min), enzyme concentration (from 0.025 to 5 mL/L), and temperature (from 25 to 50°C). Finally, the response surface methodology using a central composite planning was applied to predict the influence of input variables to achieve the highest viscosity reduction on the evaluated range of intervals. Results showed that enzyme preparations containing combined pectinolityc, cellulase, and amylase activities presented superior levels of viscosity reduction. Enzyme concentration and temperature were the two main constraints on the enzymatic liquefaction, whereas the incubation time did not have influence in the results after 30 minutes of reaction. The statistical analysis of the central composite planning showed that the best concentration and temperature values were lmL/L and 50°C, respectively, within the investigated interval. © 2011, AIDIC Servizi S.r.l.