Postharvest hydrothermal treatments to maintain quality of ‘Newhall’ navel orange.

Abstract

Hydrothermal treatments are long known curing methods for the improvement of fruits resistance against storage conditions and for controlling fungal pathogens. The optimal conditions of the hydrothermal treatments significantly vary among species and varieties/cultivars. Present research was conducted to measure the storability effect of hot water dipping (HWD). First of all, three different hydrothermal temperatures (45, 50 and 55°C) tested for 3 different HWD durations (3, 4 and 5 min). Hereafter, main studies were performed with 50°C for 5 min HWD treatment which provided highest performance in preliminary experiments. In this main studies, physical, bio-chemical, physiological and enzymatic characteristics of the fruits were also tested with 20 days interval for 120 days of storage. Results suggested that the HWD treatment reduce respiration rate and enhance the activity of some enzymes, mainly polyphenol oxidase (PPO), peroxidase (POD) and superoxide dismutase (SOD), and helps to preserve physical and bio-chemical quality of ‘Newhall’ navel oranges.