This study reports the optimization of ultrasonic treatment combined with sodium hypochlorite (NaOCl) solution on kiwifruit (Actinidia deliciosa) to evaluate its effect on microbial population, respiration rate and its textural quality. Response surface methodology (RSM) based on four factors three level central composite design was applied to investigate the effects of process variables on ultrasonic treatment. Four independent variables include ultrasonic intensity (184-368W/cm(2)), temperature (25-40°C), treatment time (8-15min) and concentration of the solvent (30-60ppm) were considered for this study. According to RSM analysis, the optimal treatment parameters obtained were ultrasonic intensity (368W/cm(2)), temperature (25°C), treatment time (8min) and concentration of the solvent (30ppm). Microbial population, respiration rate and some quality parameters were compared with NaOCl treated kiwifruits. An ultrasound combined with NaOCl was found to be the most effective treatment in inhibiting the microbial growth (bacteria, yeast and mold) and preserving the quality of kiwifruits, and these results suggest that the ultrasound treatment may provide an alternative for extending the shelf life of whole kiwifruit, maintains the quality of fresh cut kiwifruits and further increases the shelf life of chitosan coated fresh cut kiwifruit.

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Fresh juice of fully ripe tomato was subjected to ohmic heat (OH) treatment (908C for 1 min) and the effectiveness of treatment was compared with conventional hot break (CT) treatment (908C for 5 min). PG (Polygalacturonase) and PME (Pectin methyl esterase) enzyme inactivation achieved by the OH (1 min.) was similar as compared to CT of 5 min. During the kinetic analysis it was observed that the inactivation of PME & PG enzyme and degradation of ascorbic acid followed first order trend in ohmic as well as conventional treatment of tomato juice, however total color change (DE) was found to follow least-squares non-linear parameter algorithm behavior. Thermal treatments leads to the increased release of phyto-chemicals from the matrix which results in a significant (p<0.01) increase in lycopene content during the early phases of the treatments. The Paste (2860.5 8Brix) obtained after pre-treatment was analyzed for lycopene, ascorbic acid content and apparent viscosity and color. OH Paste was found more viscous than CT treatment with maximum viscosity of 2.333103 mPa-s. The color of OH treated paste was bright red as compared to CT treatment, however the lycopene and ascorbic acid content of paste were found similar in OH and CT. Based on results of present study it is concluded that the ohmic treatment may be applied as an efficient alternative to the conventional method of enzyme inactivation in tomato juice. K E Y W O R D Scolor, enzyme inactivation, kinetics, ohmic heating, tomato juice J Food Process Eng. 2017;40:e12464.