Study Of LED And UV-C Irradiation On Quality Maintenance In Postharvest Brassica Chinensis L During Cold Storage

Vegetables are high in water content. Their tissues are fragile. It is very easy for vegetables to get irreversible damage under harvesting, storage or sales process, which could cause serious waste. So the storage of fresh vegetables can be especially difficult. Chemical preservative agent, such as sodium hypochlorite, is commonly used. But this method can result in loss of vitamin C and some other nutrients. Moreover, there may be residual toxic and harmful substances after chemical treatment. This research studied the storage characteristics of ten common vegetables. And Brassica chinensis L was chosed as the experimental subject. After that, light and UV-C treatment on quality maintenance in postharvest Brassica chinensis L during cold storage was studied, in order to provide a new method and theoretical basis for postharvest vegetable storage. The main results and conclusions are as follows:1. The storage characteristics of ten common vegetables were studied. The results showed that lettuce, Brassica chinensis L and youmai vegetable had the worst sensory quality after 12 days of storage. Brassica chinensis L and lettuce had the highest weight loss. The most serious browning was found in Brassica chinensis L and Chinese flowering cabbage. Brassica chinensis L had the most serious loss of chlorophyll content. The loss of reducing sugar and total souble solid was also found in Brassica chinensis L. After comprehensive consideration, Brassica chinensis L was chosed as the experimental subject.2. In order to study light treatment on quality maintanence in Brassica chinensis L during cold storage, different wavelengths, light intensities and light sources were used. When different wavelengths of LED irradiated Brassica chinensis L, the subjects irradiated by red LED maintained the best storage quality. When different light intensities of red LED irradiated Brassica chinensis L, the subjects irradiated by red LED with 517 lux maintained the best storage quality. When red LED, fluorescent and white LED irradiated Brassica chinensis L, the subjects irradiated by red LED maintained the best storage quality. There was no significant difference between luorescent and white LED irradiation(P>0.05). To conclude, red LED with 517 lux irradiation had the best preservation effect on Brassica chinensis L storage quality.3. Different UV-A and UV-C irradiation doses were used to treat Brassica chinensis L. After 12 days of storage, the Brassica chinensis L treated by UV-A irradiation didn’t have any difference with control(P>0.05). But the Brassica chinensis L treated by UV-C irradiation with 0.5 kJ/m2 and 2 kJ/m2 were proved to have better quality than control(P<0.05). And UV-C irradiation with 0.5 kJ/m2 had better preservation effect on Brassica chinensis L than UV-C irradiation with 2 kJ/m2(P<0.05). But excessive dose of UV-C irradiation(8 kJ/m2) had a worse influence than control(P<0.05).4. The mechanism of red LED and UV-C treatment on postharvest Brassica chinensis L was studied. After red LED and UV-C treatment, the growth of microorganisms was inhibited during storage. Ethylene production and respiration intensity were reduced. What’s more, the antioxidant activity was improved after treatment. In this way, the aging of Brassica chinensis L slowed down and Brassica chinensis L maintained high quality after storage.