[4-1015-A] Postharvest/Food Technology and Process Engineering (1)

[4-1015-A-04] Impact of Low Electric Field on Physicochemical Properties and Antioxidant Activity of Persimmon (Diospyros kaki)

Naruesorn Jaisue^1,2, Sutthiwal Setha^1,2, Daisuke Hamanaka³, *Matchima Naradisorn^1,2 (1. School of Agro-Industry, Mae Fah Luang University, Chiang Rai, Thailand(Thailand), 2. Research Group of Postharvest Technology, Mae Fah Luang University, Chiang Rai, Thailand(Thailand), 3. Faculty of Agriculture, Kagoshima University, Kagoshima, Japan(Japan))

キーワード：Electric field, Non-thermal technology, Persimmon, Total phenolic content, Antioxidant activity

Electric field technology is a mild preservation technology that has been recently applied to maintain nutritional and physicochemical properties of food products; and improve juice yield and polyphenol extraction in fruits. In fresh fruit, high electric field treatment showed its efficacy in suppressing respiration rate of pear, plum and banana; and delaying ripening of mature green banana and sweet pepper. However, electric field with high voltage affects texture of some fruits and vegetables by causing loss of turgor and crack of cell membranes. The use of low electric field (LEF) may be of interest as an effective tool to maintain postharvest quality of fresh fruits without causing defects. The aim of this study was to investigate the effect of low electric field (LEF) on physicochemical properties and antioxidant activity of persimmon (Diospyros kaki). Persimmon fruit were exposed to electric field strength of 7 kV/cm during storage at 10 °C. Persimmons stored at 10 °C without LEF treatment were used as a control. Analyses were performed at 3-day intervals during storage. The results showed that the firmness of persimmon fruit treated with LEF during storage for 9 days were significantly higher (P < 0.05) than those in the non-LEF storage condition. Exposure of LEF for 3 and 9 days significantly increased (P < 0.05) total phenolic content and antioxidant activity in persimmons. There was no significant difference in weight loss, colour (L^*, a^*, b^* values) and respiration rate among LEF-treated and untreated persimmons. After 15 days of storage, application of the LEF treatment for 9 days prior to storage at 10 ^oC significantly increased (P < 0.05) total phenolic content in pulp and peel by 55.76% and 41.09%, respectively, in comparison to the non-LEF treatment. This study suggests that exposure to low electric field strength during storage may be useful for prolonging shelf life of persimmon; and for producing and preserving persimmon product with high total phenolic content and antioxidant capacity.