The storage quality and nutritional components of spinach and leek were well maintained after UV LED irradiation. The change of chlorophyll content is a typical feature of leaf senescence. With leaf senescence, the content of chlorophyll in tissue decreased significantly. This study found that led UV treatment could delay the decline of chlorophyll content in spinach and leek leaves. In the process of plant senescence and storage, enzymes can cause the decomposition and destruction of chlorophyll. UV LED irradiation can inhibit the activity of enzymes, alleviate the decomposition rate of chlorophyll, and improve the preservation rate of chlorophyll.

Since vegetables contain enzymes that promote VC oxidation, VC will gradually decrease during storage, and the rate of reduction is closely related to storage conditions. In addition, the instability of VC itself leads to serious loss of VC. UV LED irradiation can inhibit the activity of oxidase, alleviate the oxidation rate of VC and improve the preservation rate of VC.

Similarly, the changes of soluble protein content in vegetables are also related to enzyme activities and respiratory intensity. For example, peroxidase can decompose and destroy protein and affect the nutritional value of vegetables. Therefore, UV irradiation inhibited the activity of enzymes, suppressed the respiratory intensity of vegetables, reduced the consumption of soluble protein and other nutrients, and extended the shelf life.

Led in refrigerator UV lamp can emit ultraviolet light with wavelength of 265nm. It is easy to be absorbed by protein and nucleic acid of bacteria and viruses. It can denature and dissociate proteins. Thymidine dimer is formed in nucleic acid, which destroys DNA and RNA structures of various viruses and bacteria. As a result, bacteria and viruses die in a few seconds. The sterilization efficiency is as high as 99%. It can kill the bacteria that can not be sterilized by other disinfection methods Bacteria. Therefore, the installation of UV LED lamp in the refrigerator can sterilize the air in the refrigerator and purify the food storage environment.