1-methylcyclopropene (1-MCP) and chitosan maintaining quality and its mechanization of postharvest jujube fruit

Abstract: Gray jujube has been planted in Xinjiang for more than 50 years, and is considered as the leading variety of jujube industry in Xinjiang. However, the harvesting period of gray jujube is concentrated, and it is easy to soften and mildew. Therefore, dry gray jujube has become the main commodity mode, even if this will seriously affect its nutritional quality and commodity value. In fact, fresh gray jujube has better flavor and higher quality than other fresh jujube varieties. Therefore, it is necessary to build a green and efficient preservation technology to extend the storage and preservation period, and promote the commercialization of fresh gray jujube. AnsiP-S, a paper-type 1-MCP sustained-release agent, which can maintain good stability during storage, accurately controls treatment concentration, and is easy to operate, so it can be used for commercial storage of fruits; Chitosan (COS) is a kind of biodegradable polysaccharide polymer with remarkable effects on disease inhibition and antibacterial activity, which is considered to be an effective and pollution-free storage and preservation method. Taking gray jujube as test materials and dealing with AnsiP-S and COS, to study the effect of optimal concentration and compound treatment on the storage quality of fresh gray jujube. The polyphenol oxidase (PPO) ,lipoxygenase (LOX) and malondialdehyde (MDA) on fruit senescence and membrane lipid peroxidation were described, and the importance of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) in antioxidant enzyme system were explored, it is hoped to provide theoretical reference for the application of jujube preservation technology. The results showed that 1.50 μL/L 1-MCP treatment had a better effect on the storage of gray jujube fruit at (0 ± 1)°C (relative humidity 90%-95%); 1% COS had a good effect on inhibiting fruit rot rate and weight loss rate; while the combination of 1.50 μL/L 1-MCP and 1% COS had the best effect, which was conducive to maintaining the storage quality of gray jujube fruits, delaying the senescence of gray jujube fruits and prolonging the shelf life. The decay rate and weight loss rate of 1-MCP+COS decreased by 53.4% and 51.2% respectively compared with CK, and the TSS content increased by 18.6% at the end of storage,The difference was significant (P<0.05), and the hardness of 1-MCP+COS was still higher than that of CK for 60 days, the peak of respiration and ethylene rate were delayed for 10 days, and the peak values decreased by 12.5% and 44.3% respectively. The activities of PPO, LOX and MDA were significantly inhibited, and the activities of antioxidant defense enzymes were increased: the peak level of SOD increased by 58.2%, the peak value of CAT increased by 34.8%, the POD activity of 90 days was 1.98 times of CK, and the APX activity was 51.7%. It can be seen that 1-MCP+COS treatment is an effective storage technology to prolong the shelf life and improve the quality of gray jujube after harvest.