EVALUATION OF OHMIC HEATING SYSTEM FOR PRESERVATION OF PASSION FRUIT PULP

Abstract

Passion fruit, a flowering tropical vine that grows in warm climate has recently gained a lot of attention because of its rich source of powerful antioxidants and healthful nutrition profile. Due to its perishable nature, the need for its processing is also increasing. For this purpose several non-thermal and thermal techniques are gaining attention all over the world. One among them is Ohmic heating. Ohmic heating with its many advantages, is a volumetric heating mechanism, where food is heated by its electrical resistance. in order to preserve passion fruit pulp with higher retention of its nutritional value, ohmic heating was applied using an ohmic heating system consisting of ohmic heating chamber, electrodes, variable transformer and control panel. The effect of ohmic heating parameters – voltage , temperature and holding time on different physicochemical properties of passion fruit pulp was also studied and the optimal condition for ohmic heating treatment of passion fruit pulp with minimal losses was found. Also the microbial population of the optimized sample was determined. From the results obtained it was concluded that the increase in ohmic heating parameters has caused an decrease in ascorbic acid,L* and b* values of passion fruit pulp while TSS and a* values of the pulp was found to be increasing. The ttrable acidity of the pulp was not much affected by ohmic heating. By analyzing the results a voltage of 185.34 V, process temperature of 60.26°C and holding time of 2.32 min was found to be the optimal condition for ohmic heating treatment of passion fruit pulp The microbial population was found to be significantly low in treated sample. So by using the optimal conditions, ohmic heating can be successfully used for preservation of passion fruit pulp with minimum losses.