Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Effect of calcium lactate in combination with hot water treatment on the nutritional quality of persimmon fruit during cold storage Fahimeh Naser a , Vali Rabiei a , Farhang Razavi a , Orang Khademi b, ⁎ a Department of Horticulture, Faculty of Agriculture, University of Zanjan, Zanjan, Iran b Department of Horticulture, Faculty of Agriculture, Shahed University, Tehran, Iran ARTICLE INFO Keywords: Antioxidant Combined treatment Firmness Persimmon Storability ABSTRACT Quality reduction and quick softening, occurring after harvest, limit shelf-life of persimmon fruit. In the present research, the effects of hot water and calcium lactate treatments on maintaining the firmness and preserving the quality of persimmon fruit during cold storage were investigated. ‘Karaj’ persimmon was harvested at com- mercial maturity stage and treated with hot water at three levels of 25 °C for 25 min, 45 °C for 30 min and 50 °C for 20 min, and calcium lactate at three levels of 0, 0.5 and 1%, and their combinations. The treated fruits were then stored at 1 °C with a relative humidity of ≥80%. At 20 and 40 days of the storage, fruits were removed from the refrigerator and some traits were evaluated three days after storage under shelf-life conditions. The eval- uated traits were calcium content, firmness, weight loss, soluble tannin content, carotenoid, ascorbic acid, an- tioxidant capacity, total soluble solids and titratable acidity. The results showed that the amount of calcium in fruit tissue increased only in calcium lactate treatment, and hot water treatment showed a small effect on the trait. The combination of calcium lactate and hot water treatments caused higher effect on maintaining the firmness, controlling weight loss and preserving the quality of fruit when compared to applying each treatment alone. Furthermore, the treatments maintained antioxidant properties of the fruits during cold storage by maintaining the amount of soluble tannin, carotenoid and ascorbic acid contents. Thus, combined treatment of hot water and calcium lactate can be used to enhance antioxidant properties and preserve nutritional quality of persimmon fruits during postharvest storage. 1. Introduction Persimmon (Diospyros kaki Thunb.) is an important subtropical fruit appreciated by consumers due to its excellent qualitative attributes and bioactive compounds such as condensed tannins, polyphenols, car- otenoids and vitamins (Bibi et al., 2007; Bubba et al., 2009). Persimmon is highly perishable climacteric fruit that may deteriorate quickly when stored at ambient temperature (Zheng et al., 2005). Therefore, low temperature is the most effective method to slow the ripening process as well as decay development of this fruit. However, this fruit is sen- sitive to chilling injury during cold storage (Besada et al., 2008). Ex- ternal browning and softening are two of the main chilling injury symptoms observed in persimmon fruit, however its susceptibility to chilling injury depends mainly on the cultivar and storage temperature (Besada et al., 2008; Khademi et al., 2012). Thus, it is necessary to develop a suitable technology to reduce chilling injury and maintain overall quality of the persimmon fruit during cold storage. Recently, heat treatments have gained much attention for use as an environmentally friendly technology for the maintenance of postharvest quality of many horticultural crops. Previous studies have shown that hot water treatment is effective in reducing chilling injury in persimmon (Besada et al., 2008; Burmeister et al., 1997; Khademi et al., 2014), maintaining fruit quality in Thai lime (Kaewsuksaenga et al., 2015), delaying the normal ripening and senescence in straw- berry (Civello et al., 1997) and controlling postharvest diseases in peach (Jemric et al., 2011). Huan et al. (2017) reported that hot air and hot water treatments maintained fruit quality, decreased reactive oxygen species (ROS) levels and enhanced the antioxidant ability of fruit under cold storage. However, hot water treatment was more ef- fective than hot air treatment in alleviating internal browning symptom in peach fruit. In persimmon fruit, Khademi et al. (2012) showed that hot water treatment alleviated flesh browning during cross from packing line, which was related to enhancing the activity of catalase and ascorbate peroxidase and reducing the activity of peroxidases. Moreover, persimmon fruits treated with hot water and 1-MCP main- tained higher firmness resulting from lower activities of pectin me- thylesterase and polygalacturonase, which were concurrent with higher catalase and lower peroxidase activities (Khademi et al., 2014). In https://doi.org/10.1016/j.scienta.2018.01.036 Received 3 October 2017; Received in revised form 11 January 2018; Accepted 15 January 2018 ⁎ Corresponding author. E-mail address: o.khademi@shahed.ac.ir (O. Khademi). Scientia Horticulturae 233 (2018) 114–123 0304-4238/ © 2018 Elsevier B.V. All rights reserved. T