Numerical optimization of hypochlorous acid (HOCl) treatment parameters and its effect on postharvest quality characteristics of tomatoes

The present study aimed at the numerical optimization of process variables to analyze the effect of hypochlorous acid (HOCl) treatment on postharvest quality characteristics of tomatoes. Box Behnken design was used to optimize the process variables, including concentration (40, 60, and 80 ppm), pH (4, 5, and 6), and dipping time (2, 4, and 6 min), and their effect on responses, i.e., weight loss (%), redness (a*), and microbial load (log cfu/ml). The optimized values of HOCl treatment process variables were found to be concentration (80 ppm), pH (4), and dipping time (6 min), and the corresponding responses were 11.69% (weight loss), 21.09 (redness), and 4.79 log cfu/ml (microbial load). The effects of different treatments, i.e., HOCl treatment (optimum values), ClO2 treatment (concentration 60 ppm, dipping time 15 min), and control (tap water), on weight loss (%), firmness (N), TSS (%), redness (a*), and microbial load (log cfu/ml) were compared for 10 days of storage (ambient conditions). Results revealed that decay rates for HOCl-treated tomatoes were significantly lower (54.86%) in comparison to ClO2 treatment (79.16%) and control samples (97.22%) at the end of the storage period, indicating the effectiveness of HOCl treatment. However, the microbial load in the HOCl-treated samples was significantly lower (7.61 ± 0.01 log cfu/ml), followed by ClO2 (8.39 ± 0.04 log cfu/ml) in comparison to control samples (10.14 ± 0.02 log cfu/ml) during the storage period. It could be concluded that HOCl could be used as a disinfectant for enhancing the shelf life of tomatoes and ensuring microbial safety.