Postharvest Biology and Technology 41 (2006) 252–259 Low temperature conditioning reduces postharvest chilling injury in loquat fruit Chong Cai a , ChangJie Xu a , LanLan Shan a , Xian Li a , ChunHua Zhou a , WangShu Zhang a , Ian Ferguson a,b , KunSong Chen a,∗ a Laboratory of Fruit Molecular Physiology and Biotechnology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Biotechnology, Huajiachi Campus, Zhejiang University, Hangzhou 310029, People’s Republic of China b The Horticulture and Food Research Institute of New Zealand, Private Bag 92169, Auckland, New Zealand Received 7 December 2005; accepted 29 April 2006 Abstract Chilling injury occurs in loquat (Eriobotrya japonica Lindl. cv. Luoyangqing) fruit when they are stored at temperatures lower than 5 ◦ C. In attempts to reduce this chilling injury, the effect of low temperature conditioning (LTC) was examined. Loquat fruit were conditioned at 5 ◦ C for 6 days before 0 ◦ C storage for up to 54 days. Control fruit stored at 0 ◦ C exhibited severe symptoms of lignification and tissue browning, and a decrease in percentage juice. LTC treatment significantly reduced these chilling injury symptoms, and doubled storage life. In terms of acceptability (tissue browning, internal browning (IB) index <0.4; fruit decay, <10%; flesh firmness, <6.0N; percentage juice, >60%), fruit could only be stored for 40 days at 0 ◦ C with a 3 days shelf life at 20 ◦ C, while LTC fruit could be stored for 60 days at 0 ◦ C with a similar shelf life. Similarly, LTC fruit could be stored for 40 days with a 5 days shelf life at 20 ◦ C, while fruit could be only stored for 20 days at 0 ◦ C with a 5 days shelf life. Our results confirm that LTC can effectively alleviate postharvest chilling injury of loquat fruit and may provide longer storage life with acceptable external and internal quality. © 2006 Elsevier B.V. All rights reserved. Keywords: Loquat; Chilling injury; Lignification; Browning; Fruit quality 1. Introduction Loquat (Eriobotrya japonica Lindl.) fruit are chilling sen- sitive, and low temperature injury is a major limitation for long-term storage of the fruit. Chilling injury occurs at tem- peratures below 5 ◦ C, and is expressed as flesh woodiness, adhesion of peel to the flesh, leathery and juiceless pulp and internal browning (Lin et al., 1999; Zheng et al., 2000a; Ding et al., 2002; Cai et al., 2006a). We have previously found that ‘Luoyangqing’ loquat fruit retained better quality after 39 days at 5 ◦ C than at 0 ◦ C(Cai et al., 2006a,b). Storage at temperatures below 5 ◦ C may result in longer storage life, so long as chilling injury can be minimised. This can be reduced in loquat fruit by a number of postharvest techniques, including modified atmosphere packing (MAP) ∗ Corresponding author. E-mail address: akun@zju.edu.cn (K. Chen). (Ding et al., 2002), and polyamine treatments (Zheng et al., 2000b). Although these treatments can reduce chilling injury to varying degrees, their effect is incomplete and has impli- cations for other aspects of fruit quality. Low temperature conditioning (LTC) is an alternative technique for increasing tolerance to low temperatures. Fruit and vegetables conditioned by exposure to temperatures slightly above the critical chilling range have been found to be more resistant to subsequent lower temperatures (Wang, 1982, 1993). The crucial factors of this technique are tem- perature differences between conditioning and storage tem- perature and the duration of the conditioning treatment. For example, a 7 days exposure of grapefruit to 10 or 15 ◦ C can prevent, or significantly reduce, chilling injury during low temperature (0 or 1 ◦ C) storage (Hatton and Cubbedge, 1982). Woolf et al. (2003) have also shown that a 6 or 8 ◦ C treatment for 3–5 days prior to 0 ◦ C storage reduced external chilling injury of ‘Hass’ avocados. 0925-5214/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.postharvbio.2006.04.015