Effects of chitosan/nano-silica on postharvest quality and antioxidant capacity of loquat fruit during cold storage

• The chitosan/nano-silica hybrid is synthesized and applied to loquat storage at 5 °C.
• The hybrid film enhances contents of reducing sugars and activates sugar signals.
• Antioxidant activity of loquat fruit is enhanced by the hybrid film.
• The hybrid film improves chilling resistance and quality of loquat fruit.

Loquat (Eriobotrya japonica Lindl.) fruit has a very short shelf-life during ambient temperature storage, and is susceptible to cold storage appearing chilling injury symptoms. The effect of chitosan/nano-silica coating on chilling tolerance in white-flesh loquat fruit (cv Baiyu) stored at 5 °C for 40 d was investigated. In comparison with control fruit, internal browning and weight loss in chitosan/nano-silica treated fruit were significantly delayed. Likewise, the decrease of total soluble solids (TSS) and titratable acidity (TA) was also inhibited. Glucose and fructose contents increased from 11.31 to 12.76 g kg−1 and from 33.20 to 44.37 g kg−1, respectively. The increase of reducing sugars contributed to the improvement of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities, reaching the peaks of 623510.12, 462371.21 and 41114.35 U kg−1, respectively. Enhanced activities of antioxidant enzymes markedly alleviated the generation of superoxide anion (O2−) and hydrogen peroxide (H2O2). Low levels of malondialdehyde (MDA) and membrane permeability in chitosan/nano-silica treated fruit were also detected, ranged from 4.35 to 8.31 mmol kg−1 and from 24.32 to 43.45%, respectively. Moreover, activities of phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO) and lipoxidase (LOX) were also much lower than those in treatment alone and control fruit. Our results indicated that the use of chitosan/nano-silica coating was effective in enhancing chilling tolerance and providing a longer storage life with acceptable external and internal quality in loquat fruit.