Efficacy of Kojic Acid in Preserving Bioactive Compounds and Regulating Oxidative Enzymes in Cold-Stored Tomatoes

Abstract

Tomatoes are regarded as the most important crop in the world due to their high nutrient content and flavour. Nevertheless, their limited storability, postharvest losses, rapid deterioration, and senescence limit their marketability. This study investigated the postharvest efficacy of three treatments of kojic acid (0, 2.5, and 5 mM) on maintaining the quality and delaying the senescence of ‘Rosalina’ tomato fruits. The fruits were cold-stored at 8±1 °C with 90–95% relative humidity for a storage duration of 35 days. The results showed that treatment with 5 mM KA preserved acidity and vitamin C. In addition, senescence was delayed through the enhanced activities of antioxidant enzymes specifically catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and phenylalanine ammonia-lyase (PAL), which contributed to the reduction of reactive oxygen species. Consequently, H₂O₂ and malondialdehyde (MDA) accumulation was reduced. Additionally, kojic acid treatment limited cell wall disassembly and browning by significantly inhibiting pectin methyl esterase and polyphenol oxidase activities. Overall, kojic acid was shown to increase the storability of tomatoes and enhance their antioxidant properties postharvest.