Siti Aisyah, A.^1,2*, Hamanaka, D.³ and Hamaguchi, Y.³

^{Abstract
Tomato is a climacteric fruit with a short shelf-life, highly susceptible to softening and cell wall degradation during storage. Cold storage can slow these changes but may also induce chilling injury. Non-thermal technologies, such as electric field (EF) treatment, offer potential as alternative preservation methods. Electric fields are divided into two types: direct current (DC) and alternating current (AC). Alternating current (AC-EF) refers to electric fields in which the current’s direction varies regularly, whereas direct current (DC-EF) maintains a constant flow in one direction. However, the application of electric fields in postharvest preservation remains underexplored, particularly under lowtemperature storage conditions. Therefore, this study aimed to evaluate the effectiveness of alternating current (ACEF) and direct current (DC-EF) electric field treatments in maintaining the postharvest quality of tomatoes grown in Kyushu Island during storage at 5 °C. Tomatoes at ripening index 2 were continuously exposed to 20 V/cm EF under AC, DC, or control (0 V) conditions for 21 days. Fruit was assessed at 7-day intervals for weight loss, colour, firmness, physicochemical properties, polygalacturonase (PG) activity, and relative gene expression. A completely randomized design (CRD) was used, with three replicates per treatment. Results showed that DC-EF treatment significantly maintained firmness and suppressed PG activity compared to the control (p <0.05), although no significant differences were found in others parameters. The findings suggest that EF treatments particularly DC may contribute to texture preservation under cold storage, but their effects are limited compared to the impact of temperature alone.}

^{Keywords: electric field treatment, cold storage, firmness, polygalacturonase activity}

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