Effects of Short-Term High Oxygen Pre-Stimulation on Browning Resistance and Low-Temperature Tolerance of Fresh-Cut Potatoes in Supercooled Storage

In this study, the anti-browning effectiveness of short-term high oxygen pre-stimulation (SHOP), supercooled (SC) storage, or combined (SHOP + SC) treatment for fresh-cut potatoes was explored by evaluations on surface color, texture, phenolic anabolism, membrane integrity, antioxidant capacity, and reactive oxygen species (ROS) balancing. Furthermore, enzyme activity ratios (EA ratios) were further proposed to assess the effect of SHOP on enzymatic browning, which were defined as ratios between defense enzymes, including peroxidase (POD), phenylalanine ammonia-lyase (PAL) or catalase (CAT), and attacked enzymes including polyphenol oxidase (PPO) or lipoxygenase (LOX). As a result, SHOP + SC treatment retarded the browning and delayed the softening of fresh-cut potatoes by inhibiting the activities of related enzymes, restraining the accumulation of malondialdehyde (MDA), and promoting the synthesis of phenolic substances against their oxidation in potatoes. Besides, higher POD activities and lower BI were observed in SHOP + SC compared with SC, but PPO activities were non-statistically significant in both. At the early storage stage, the antioxidant capacities of fresh-cut potatoes treated with SHOP and SHOP + SC were enhanced, and the ROS accumulation was inhibited. Moreover, EA ratios and their changing amplitude of the SC group ranked top, followed by the control, SHOP, and SHOP + SC. Results suggested that the antioxidant capacity was reinforced by SHOP in fresh-cut potatoes due to enhanced resistance against membrane lipid damage resulting from mechanical cutting and persistent SC stimulation.