Effect Of Different Treatments On The Sugar And Acid Content And Related Enzyme Activity Of Postharvest ’angeleno’ Plums During Cold Storage

In order to study the effect of different treatments on the sugar and acid content and the enzyme activity in ‘Angeleno’ plums during cold storage, ‘Angeleno’ plums as material, using 1-MCP and ethylene processed respectively,the concentration of soluble sugar and organic acid were analyzed by the high performance liquid chromatography and the enzyme activity was analyzed by the spectrophotometer, the result showed the effect of different treatment on the metabolism of sugar, acid and enzyme activity and the change mechanism in ‘Angeleno’ plums during cold storage, which could be used to contolled the posthavest quality of plum fruit.The main research results of this paper were as follows:(1)The sugar content in ‘Angeleno’ plums were analyzed by the high performance liquid chromatography during cold storage, the results show that 4 kinds of soluble sugar content in ‘Angeleno’ plums were as follow: sorbitol > sucrose > glucose > fructose. The sorbitol content in fruit was the highest level at the beginning of the cold storage, which was 41.105 mg/g FW. The decline of sugar content significantly slow by the 1-MCP treatment, the total sugar content in fruit maintain high level, the effect of ethylene treatment on the sugar content during cold storage was reverse.(2)The enzyme activity of sugar metabolism in ‘Angeleno’ plums during cold storage were analyzed by spectrophotometer, the results show that 1-MCP treatment resulted the a-amylase、b- amylase and total amylase activity peak were delayed, AI and NI activity was lower than that in the control fruit. Ethylene treatment could lead a-amylase、b- amylase、total amylase and NI activity peak in advance, three kinds of amylase activity reached the highest peak at 25 d during cold stoage,which was 0.993 U·g-1·min-1、 0.487 U·g-1·min-1 、 1.487 U·g-1·min-1 、 6.204 U·g-1·min-1respectively, AI activity overall high in the control group. The ethylene treatment and control、1-MCP treatment process compared to sucrose and fructose acid invertase activity, between glucose levels are not relevant.(3)Seven kinds of organic acid content in ‘Angeleno’ plums of were analyzed by the high performance liquid chromatography during cold storage.The results show that the organic acid content in the ‘Angeleno’ plums were as follow: malic acid > succinic acid > citric acid > tartaric acid > oxalate acid> pyruvic acid > acetic acid. The pyruvic acid, succinic acid, acetic acid content lower than the control and ethylene treatment by the 1-MCP treatment at the end of cold storage,ethylene treatment can slow down during the cold plum fruit acid, malic acid, the rate of decline.(4)The different treatments related enzyme activity of organic acid metabolism in postharvest ‘Angeleno’ plums were analyzed by spectrophotometer during cold storage, the results show that the ACO activity in‘Angeleno’ plums was highest at the egining storage, which was 11.095 U·g-1·min-1. The enzyme activity of organic acid metabolism in ‘Angeleno’ plums were inhibited by the 1-MCP treatment, which maintain a lower level, enzyme activity of acid metabolism in ethylene tretment reached high peak more early than that in others treatment, and the enzyme activity maitain higher level than others treatment at the same time. during the treatment of 1-MCP and ethylene refrigerated NADmalic enzyme, NADP- malic enzyme and citric acid, malic acid were not correlated.(5) The different treatments related sugar-acid ratio of postharvest ‘Angeleno’ plums, the results show that during refrigeration, sugar-acid ratio of ethylene treatments were lower than the control, 1-MCP treatment, refrigerated 50 d, the lowest value, which is 11.410%, respectively, compared with the control, 1-MCP treatment of low 19.05%, 30.53%(p <0.01).