Effect of processing and concentration methods on the quality of passion fruit concentrate

The hybrid passion fruit variety (Passiflora edulis Sims. * Passiflora edulis f. flavicarpa) were used in this study. The effects of enzyme treatment and centrifugation and process parameter e.g. temperature, transmembrane pressure, feed flow rate on the efficiency of the MF (microfiltration)/UF (ultrafiltration) process and the quality of permeate obtained in terms of flux, rejection of acid, flavor, total solid and turbidity were found. The juice treated with 200 ppm for 60 minutes and then centrifuged at 9000 rpm for 10 minutes was found to be suitable for the membrane process as it could increase the permeation rate. The membrane having molecular weight cut off of 100,000 gave the highest processing capacity. Increasing the pressure and feed flow rate to 4.0 bar and 12.2 l/min facilitated the efficiency of MF/UF membrane. Two membrane modules, namely flat sheet and tubular, were used to evaluate the processing capacities in both MF and UF modes. The flat sheet module possessed 50.79 and 27.45 % higher permeate flux than the tubular MF and UF, respectively at Pavg of 3.5 bar and feed flow rate of 9.07 l/min. But the tubular one was superior in flavor retention. A pilot scale plate and frame UF-RO (reverse osmosis) system equipped with high resistance (HR) membranes, HR-95 was operated at pressure of 50 bar and 20 deg C. At this condition, it possessed the highest processing capacity of 16.0 LMH (l/square m.hr) and concentration limit of 28 deg Brix for UF permeate. It had high recovery of solids and flavor volatiles. The recoveries of more than 96 % solids and acid, and also about 100 % volatiles were obtained. The concentrate could be reduced about 65 to 80 % in volume. Finally, the reconstituted samples were compared in quality aspects with fresh prepared passion fruit juice and reconstitute commercially concentrate. The quality of the juices passing through RO and UF process had higher overall quality than the conventional concentration process.