Studies On The Physiochemical Characteristics Of Fresh-cut Lotus Root And Brasilca Campestris L.vat. Purpurea L.Baileys In Storage

Fresh-cut vegetables and fruits are newly developed product. But cutting destroys the membrance integrity which enhance the respiration rate and result in browning, microbe proliferation and nutritional lose. Based on the principle of fresh-cut processing ,this thesis select Nelumbo Nucifera Gaerth and Brasilca campestris L. vat. purpurea L.Baileysh as the testing material to study the proper keeping-fresh method and prolong the shelf life.The physiological reactions of fresh-cut lotus root was: processing such as cutting led to enhance the respiration rate and result in combining phenols and PPO which are isolated by membrane in intact lotus root. The studies showed the main factor that affect the quality of fresh-cut lotus root were browning and softening. As to the browning, this paper screened out the optimized concentration of browning inhibitor by the uniform design. The result was: 0.2% citric acid +0.7%Vc+0.3% or 0.4% calcium chloride +0.2 % sodium pyrophosphate. At the same time , the activity of PPO, SSC, browning degree and the total phenols content were studied during the storage.As to the softening, the method of dipping with 0.5% CaCl₂ and 0.5% CaCl₂+20mg/L Naphthy-acetic-acid(NAA) each were uses , and then stored at 5℃. The hardness, content of malondialdehyde(MDA), membrane permeability, SOD , PE, PG and the content of calcium in different forms of fresh-cut lotus root were tested. It was suggested that hardness , the content of MDA and SOD were significantly different with the CK(p<.05). Besides, the relationship between the content of calcium in different forms and the physiochemical index was primarily studied.The physiological reactions of fresh-cut Brasilca campestris L. vat. purpurea L.Baileysh was: microbe proliferation and aging in the form of fibrosis and hollow. As to the microbe proliferation, the treatment of different dosages such as 1.5kGy, 3kGy and 4.5kGy ⁶⁰Co irradiation was used, and then stored at 5℃. The total number of bacteria and fungi were determined by the GB4789—1994. The content of Vc and total sugar, SSC and the activity of PPO were tested. It was suggested that irradiation could restrain the physiological activity and the enzyme activity, and the more dosage of irradiation , the Brasilca campestris L. vat. purpurea L.Baileysh was easier to decay, but more Vc was lost. The best proper dosage was 1.5kGy which can relatively preserve the sense and the nutrition.As to the aging, the treatment of modified atmosphere package(MAP) was used. Three different MAP such as PE, PE/PA and PA were designed according to the respiration characteristic. The content of Vc ,total sugar, soluble protein , cellulose and the activity of PPO,POD cellulase were tested .It was suggested that MAP treatment could restrain the physiological activity, suspend the activity peak of PPO, but the content of Vc and total sugar had no significant difference with the CK(p<0.05). The proper treatment was MAP of PE.