The Effect of Different Thickness Polyethylene Bags on Litchi Browning during Cold Chain Logistics

This study used polyethylene bags with thicknesses of 10, 20, and 30 µm to package "Jizuili" litchi, combined with ice bags to simulate logistics packaging, to study the effect on litchi peel browning, cell membrane permeability and anthocyanin metabolism under the current imperfect cold chain logistics system, in order to explore simple and efficient litchi fresh-keeping logistics technology for actual production. The results revealed that 20 μm polyethylene bags had better packaging effects, followed by 10 μm thickness, and the worst was 30 μm, by analyzing of pericarp browning, commercially acceptable rate and fruit color difference components during storage. And the 20 μm thickness polyethylene bags distinctly inhibited the increase in membrane permeability, which was reflected in the lower relative electrical conductivity of the fruit during storage (P<0.05). Further research results indicated that the 20 μm polyethylene bag delayed the decomposition of anthocyanin via inhibiting the activity increase of phenylalanine ammonia lyase, the key enzyme of anthocyanin biosynthesis, combined with inhibiting the activities of polyphenol oxidase and peroxidase to delay the browning of the litchi. In summary, compared to other thicknesses, 20 μm polyethylene bags can significantly inhibit litchi browning, effectively maintain fruit quality and extend shelf life.