Optimization of the Ohmic Heating Parameters for Pasteurization of Mango Pulp using Response Surface Methodology

Abstract

The present investigation optimized the ohmic heating variables influencing the quality parameters of mango pulp during pasteurization. Three independent variables such as voltage gradients (10–20 V/cm) of ohmic heating, pulp temperature (60–80℃) and pulp concentration (6–14 °Brix) were experimented using Box-Behnken experimental design of response surface methodology. The models generated for the quality parameters as responses such as ascorbic acid, total phenol content, overall acceptability, mold load and bacterial load were tested for their validity using ANOVA. The optimum conditions for pasteurization of mango pulp through ohmic heating were found to be 19.5 V/cm, 75°C and 9.96 °Brix respectively for voltage gradient, pulp temperature and pulp concentration. The values of corresponding quality parameters of ascorbic acid content, total phenolics content, overall acceptability, yeast/mold load and bacterial load were estimated to be 129.39 mg/100g dm, 288.006 mg GAE/100 g dm, 7.40, 11.01 cfu/ml and 162.299 cfu/ml respectively. The results were experimentally verified within a deviation of ±0.5%. Structural variations and functional compounds of fresh, conventionally heated and ohmic heated samples at optimum conditions were analyzed through SEM and FTIR respectively. The ohmic heated sample was found superior over conventionally heated sample with maximum retention of quality parameters. Further, the rheological analysis depicted the closeness of ohmic heated (optimum) sample with the fresh sample.