Effect of a high voltage electrostatic field (HVEF) on the shelf life of persimmons (Diospyros kaki) Chi-En Liu a , Wen-Ju Chen a , Chao-Kai Chang b , Po-Hsien Li a , Pei-Luen Lu c, ** , Chang-Wei Hsieh a, * a Department of Medicinal Botanicals and Health Applications, Da-Yeh University,168 University Rd, Dacun, Chang-Hua, Taiwan, Republic of China b Department of Bioindustry Technology, Da-Yeh University,168 University Rd, Dacun, Chang-Hua, Taiwan, Republic of China c Department of Bioresources, Da-Yeh University,168 University Rd, Dacun, Chang-Hua, Taiwan, Republic of China article info Article history: Received 21 January 2016 Received in revised form 26 August 2016 Accepted 30 August 2016 Available online 31 August 2016 Keywords: High voltage electrostatic fields Diospyros kaki Malondialdehyde Oxidative Organizational deterioration Carbon dioxides yield abstract This study investigated the effects of HVEF as a potential postharvest technology in persimmon culti- vation (Diospyros kaki). We used an electric field strength of 600 kV/m and treated samples for different lengths of time (0, 30, 60, 90 or 120 min) before storing the fruit for 15 d. The results showed that HVEF can reduce the rate of weight loss by 1.0e3.4-fold, demonstrating not only that HVEF has the ability to delay tissue deterioration but that the effect increases with treatment time. HVEF also delays the rate of decreasing hardness by 1.0e1.3-fold, indicating that it may have the ability to inhibit the activity of tissue enzymes. HVEF further demonstrated the ability to suppress the rate of malondialdehyde (MDA) pro- duction by 1.46e11.22-fold; increasing the treatment time improved the efficacy of the inhibition. HVEF can also delay the decreasing rate of carbon dioxides yield by 1.0e2.3-fold, indicating that it has the ability to inhibit metabolism. This inhibition rate of carbon dioxides yield also results in a delay of organizational deterioration. Finally, HVEF inhibited pectinesterase activity and had no impact on the amount of total phenols. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Persimmons (Diospyros kaki) have high economic value in most Asian countries and Asian markets but a short shelf life as their flesh rapidly loses firmness at warm temperatures and softens over a short period. This is accelerated by the removal of its astringency, a factor that greatly influences consumer acceptability of the fruit. The prevention of flesh softening in non-astringent persimmon is a critical issue not only for the export of persimmons but also in regard to the domestic supply in many Asian countries, particularly in areas with a tropical climate. Compared to other climacteric fruit, the ripening of non-astringent persimmon is very sensitive to ethylene (Park, 2012). Once ethylene is activated, fruit respiration and softening speeds up, producing a large amount of lipid hy- droperoxides (Davey, Stals, Panis, Keulemans, & Swennen, 2005). Peroxides of polyunsaturated fatty acids generate malondialdehyde (MDA) upon decomposition; in many cases, MDA is the most abundant individual product from aldehydic lipid breakdown (Davey et al., 2005). Pectinerase (PE) is involved in the ripening and pectin degradation of persimmons (Nakamura, Wakabayashi, & Hoson, 2003), playing a key role in cell wall degradation and thus negatively influencing fruit firmness (Gwanpua et al., 2016). Therefore, finding a new method to reduce persimmon softening and senescence would provide a much needed postharvest technology. Currently, preservation technologies fall into one of three cate- gories: physical, chemical or biological. However, with harmful substances (radiation, sulfur dioxide, etc.) the residual operation processes remain cumbersome and require a high degree of training, knowledge of the risks and costly equipment. Using a low temper- ature is the most common way to extend the shelf life of fruits and vegetables, in addition to transferring gas packaging (Galvis- S anchez, Fonseca, Morais, & Malcata, 2004). However, lowering the temperature, increasing the relative humidity and controlling the concentration of CO 2 and O 2 require more complex technology and entail a higher cost. In addition, people are more concerned about environmental issues; maintaining low temperatures over an * Corresponding author. ** Corresponding author. E-mail addresses: peiluen@mail.dyu.edu.tw (P.-L. Lu), welson@mail.dyu.edu.tw (C.-W. Hsieh). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt http://dx.doi.org/10.1016/j.lwt.2016.08.060 0023-6438/© 2016 Elsevier Ltd. All rights reserved. LWT - Food Science and Technology 75 (2017) 236e242