Abstract:
By taking the late-maturing longan in Ningde, Shuinan No.1, as the experimental material, the effects of heat treatment combined with different doses of ultraviolet radiation on the preservation of Shuinan No.1 longan were studied. On the basis of heat treatment at 50℃ for 10 min, the ultraviolet lamps with radiation doses of 20, 25, 30 and 35 J·m
-2 were respectively set for irradiation, while no heat treatment and no ultraviolet radiation were used as the blank control, and then the products were stored at 25℃. By measuring the weight loss rate, relative conductivity, MDA content, relative permeability of cell membrane, soluble sugar content, reducing sugar content, soluble solids (TSS) content and Vc content of longan fruit in each treatment, the optimal preservation processing of Shuinan No.1 longan was determined. The results showed that the heat treatment at 50℃ for 10 min combined with the ultraviolet radiation of 30 J·m
-2 could effectively inhibit the weight loss, the accumulation of malondialdehyde (MDA), the increase of relative conductivity and relative permeability of cell membrane of longan fruit, and also alleviate the consumption of soluble sugar, reducing sugar, TSS and vitamin C. In conclusion, the heat treatment at 50℃ for 10 min combined with the ultraviolet radiation of 30 J·m
-2 could effectively alleviate the senescence of Shuinan No.1 longan fruit, which had the effect of extending the storage period and lasting preservation.