Characterization of an optimized hot water treatment for eggplant as a non-chemical mean to maintain postharvest quality: validation of its effect on bioactive compounds and antioxidant capacity

The objective of this study was to assess the effect of an optimized hot water treatment (OHWT) on the conservation of fresh eggplants (Solanum melongena L.), which was carried out through the Response Surface Methodology (RSM). Activity of pectin methylesterase (PME), color difference and firmness parameters, as well as the anthocyanin content were optimized according to a rotatable central composite design [process variables: temperature (30–50 °C) and time (5–15 min)]. The RSM results showed an activation on PME activity (1.333–2.922 U/g FW) along with a retention on the quality attributes and optimized conditions of 40 °C and 15 min. In addition, significant differences in bioactive compound contents were observed between treatments, where a greater amount of total phenolic (17.76 mg GAE/100 g) and chlorogenic acid (5.9715 µg CA/mg ME), and fewer anthocyanins were found at OHWT compared to control. Therefore, the application of the optimized conditions (40 °C, 15 min) would be the most suitable to maintain the quality of fresh eggplants.