Kojic acid suppresses browning incidence, maintains quality and sensory attributes of harvested loquat fruit by upregulating enzymatic and non-enzymatic antioxidants

Loquat is highly susceptible to postharvest browning incidence during supply chain, which severely deteriorates the storability, market potential, eating quality, and consumer acceptability of fruit. This study aimed at elucidating the influence of pre-storage kojic acid (KA, 0, 2, 4, or 6 mM) dip treatments on postharvest browning of 'Surkh' loquat fruit during cold storage at 4 +/- 1 degrees C for 24 d and subsequent shelf period for 2 d at ambient temperature. The results demonstrated that 2 mM KA treatment significantly decreased fruit browning, weight loss, and decay incidence. Postharvest application of 2 mM KA suppressed malondialdehyde and hydrogen peroxide radical accumulation as well as lowered the activities of polyphenol oxidase and peroxidase enzymes in loquat fruit, as compared to control. Additionally, loquat fruit treated with 2 mM KA exhibited higher levels of total soluble solids, titratable acidity, vitamin C, glutathione, proline, total phenolics, total antioxidants and sensory attributes like fruit taste and consumer acceptability as compared to other KA treatments and control. Higher activities of superoxide dismutase, catalase, and ascorbate peroxidase were noted in 2 mM KA-treated loquats. In conclusion, 2 mM KA treatment could be adopted to alleviate postharvest browning, maintaining higher levels of bioactive compounds and antioxidant potential, while preserving better eating quality of 'Surkh' loquat fruit for 24 d cold storage and 2 d shelf period.