Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2020
Publication Date: 2/13/2021
Citation: Imahori, Y., Bai, J., Baldwin, E.A. 2021. Effect of storage temperature on chilling injury and activity of antioxidant enzymes in carambola "Arkin" fruit. Journal of Food Processing and Preservation. https://onlinelibrary.wiley.com/doi/epdf/10.1111/jfpp.15178.
Interpretive Summary: Carambola fruit are rich in vitamins, minerals and dietary fiber, and are one of the important tropical fruit in Florida. However, like other fresh produce, carambola fruit are highly perishable due to mechanical damage and microbial deterioration, resulting in a short self-life after harvest. Particularly, the protruding ribs are easily damaged and the fruit must be handled with great care. Cold storage is one of the most widely used postharvest technologies to extend shelf life of horticultural crops, but chilling injury occurs when storage temperature is too low. The purpose of this study was to investigate the relationship between storability and activity of antioxidant enzymes in carambola fruit stored at different storage temperatures, to determine the optimal storage condition and to reveal the possible mechanisms of chilling injury in carambola fruit.
Technical Abstract: Carambola (Averrhoa carambola L.) fruit harvested at the yellow green stage were stored at 2, 5, 10, 15 and 20 °C for 21 days then transferred to 20 °C for 7 days. Fruit stored at 20 °C reached the overripe stage after 7 days associated with soft flesh and surface blemishes. Fruit stored at 15 °C, ripened asynchronously, possibly due to slight differences in harvest maturity. Fruit stored at 2, 5 or 10 °C for 21 days ripened very slowly, however, fruit stored at 2 and 10 °C ripened quickly after transfer to 20 °C for 7 days, along with typical chilling injury symptoms, shriveling and browning. On the other hand, fruit stored at 5 °C ripened slowly, even after transfer to 20 °C, with fresh yellow color and firm texture. Activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) enzymes, directly related to reactive oxygen species (ROS) scavenging, increased during storage at 20 °C, but had their lowest values at 5 °C. Activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) enzymes, related to continual ascorbate oxidation and reduction, increased in fruit stored at 5 °C. The results indicate that 5 °C storage caused irreversible injury to the ripening metabolic process, which is beneficial for extension of fruit commercial shelf life. On the other hand, the ascorbate-glutathione pathway was enhanced by the 5 °C chilling treatment, which protected fruit from damage caused by ROS injury.