Research On1-methycyclopropene Self-assembly And In Fresh-keeping Of Fruits And Vegetables

1-Methylcyclopropene (1-MCP), as an antistaling agent for green fruits andvegetables, was synthesized and1-MCP/CD complex of1-MCP and cyclodextrin (CD)was prepared by molecule self-assembly technique. The release kinetics and antistalingeffect of the complex were also investigated in this thesis.The GC-MS showed that by-products of methylene cyclopropene, methyl allylchloride and isomer of3-chloro-2-methyl propylene, etc was produced together with1-MCP during the reaction between3-chloro-2-methyl propylene and sodamide. Purified1-MCP could be attained by transferring the product gas through dilute HCl,phenolphthalein and organic solvents (a mixture of ethanol amine and isopropyl alcohol).The1-MCP/CD complex was prepared by solution self-assembly technique. Theresults exhibited higher loading complexes were able to be assembled owing to the voidvolume of α-CD matching with1-MCP volume. Taking α-CD as host molecule andalcohol as assembly medium, the1-MCP/α-CD complex with1-MCP loading up to5.6%was synthesized by choosing assembly temperature of50℃and assembling time of8h.GC-MS results showed the assembly of1-MCP and cyclodextrin (α-CD and β-CD) wasprepared successfully. delocalization phenomenon in the double bond of1-MCPoccurred induced by high electron density of the cavity of α-CD, which ascribed to π-π*transition absorption band of the double bond of1-MCP. IR and FTIR results showed thathydrogen bond and Van der Waals forces formed during the self-assembly of1-MCP andCD.1-MCP/α-CD exhibited lower1-MCP gas release rate than1-MCP/β-CD in alkalinesolution. And the content of1-MCP of1-MCP/α-CD decreased27%after being kept inrelative humidity of20%for one year. Therefore, the stability of1-MCP/α-CD wassuperior to that of1-MCP/β-CD under dry atmosphere.Xinjiang Aksu apples after45days and tomatoes after19days began to decay.However, in presence of1-MCP/α-CD self-assembly complex, those fruits kept theiroriginal appearance and their weight decreased more slowly. And the decreasing velocityof titratable acid and vitamin C was significantly lower than that of samples withoutantistaling treatment, exhibiting excellent antistaling effect.