Effect of hydrocooling in electrolyzed water on reducing fruit rot diseases and maintaining postharvest quality of rambutan

Rambutan is one of Thailand’s major fresh fruit exports. The main problems of rambutan export are postharvest decay and rapid physiological changes during storage and transportation. Thus, the objective of this research was to investigate the effect of hydrocooling in electrolyzed water on fruit rot diseases and the quality of rambutan. ‘Rong-rein’ rambutan at color stage 4-5 were used in this study. The fruit were selected and washed in tap water. Then they were precooled in 200, 400 and 600 ppm electrolyzed water at 10°C for 3 min. Untreated fruit served as the control. All fruit were packed in polyethylene bags and kept at 13°C (90-95% RH) for 15 days. The results showed that fruit hydrocooled in 400 ppm electrolyzed water developed the lowest incidence and severity of rot, followed by fruit hydrocooled in 600 and 200 ppm electrolyzed water, whereas the control fruit showed the highest of incidence of rots. The decrease of disease correlated well with the increase of key plant defense-related enzyme activities such as phenylalanine ammonia lyase and chitinase. Additionally, hydrocooling also maintained better quality by reducing weight loss and respiration rate. However, hydrocooling in electrolyzed water did not affect to total soluble solids (TSS) and peel color of rambutan in comparison with the control fruit.