Study On The Regulation Of Sugar Metabolism Of Green Crisp Plums After Harvest And The Study Of 1-MCP Combined With Artificial Modified Atmosphere Packaging On The Fresh-keeping Effect Of Green Crisp Plums

Plums have a long history of cultivation in my country.They are crisp and refreshing,with various processing methods,and are deeply loved by consumers.According to statistics from the World Food and Agriculture Organization,my country's plum production in 2017 was 6.804 million tons,accounting for 57.8%of the world's total,ranking first in the world.Green crisp plums are mainly planted in my country's southwestern region.In Chongqing,green crisp plum is not only a leading industry for farmers in the alpine mountainous area to increase their incomes,but also an important carrier for the rural leisure experience tourism industry.However,the green crisp plum is a kind of respiration type fruit,the shelf life of the fruit after harvest is short,and the sales range is limited,which has become an urgent problem for the green crisp plum.This experiment took green crisp plum as the research object,and explored the postharvest sugar metabolism of green crisp plum fruit under 3±1?cold storage environment and the use of 1-methylcyclopropene(1-MCP)combined with artificial atmosphere control.The effect of CA(Controlled Atmosphere Storage,CA)on postharvest storage and preservation of green crispy plums has resulted in important changes in sugar metabolism in postharvest green crispy plums and the relatively optimal ratio of O₂and CO₂during postharvest storage.The main findings are as follows:(1)The ratio of six sugar components of green crisp plums after picking and their content changes during storage.Among the six sugar components of green and crisp plum fruits,the highest proportion is Pectin,which is 41.05%,and the sugar with the highest proportion of Soluble sugar is Sucrose,which accounts for soluble sugar.Content of 66.49%,Sorbitol content is the lowest,accounting for only 0.0043%,Starch,fructose and glucose accounted for the total sugar content of 9.25%,11.81%,4.61%.During the postharvest storage of green crispy plums,the changes in the content of sucrose and pectin both showed a fluctuating increase and then a downward trend.The changes in glucose and starch content were the closest,but the content of fructose was not significantly changed,and the correlation analysis results It shows that the decrease and increase of soluble sugar content during postharvest storage of green crisp plums are mainly affected by the metabolism of sucrose and glucose,and the main conversion pathway of starch is conversion to glucose.The increase in soluble sugar content is mainly affected by the metabolism of sucrose and glucose,and sucrose is the most important soluble sugar,so green crisp plum is a sucrose accumulation type fruit.(2)Through the analysis of the changes in the content of sugar components and the activity growth and decline of 14 metabolic enzymes of pectin,sucrose,starch and sorbitol,combined with correlation analysis and principal component analysis,it can be determined Green crisp plums are divided into two important processes during postharvest storage and ripening.The first stage is 7-21 days after picking,which is mainly related to the enhancement and response of sucrose,starch and sorbitol.The second stage is the 28th-35th day of postharvest cold storage.This stage is dominated by sucrose metabolism,starch metabolism and pectin metabolism.According to the load diagram and principal component analysis results,Sucrose Synthase,EC 2.4.1.13(SS-I),?-amylase(?-AL)and Soluble Acid Invertase(SAI)is the three most important sugar metabolizing enzymes that affect the accumulation of soluble sugar in green crisp plums.(3)The storage experiment of green crisp plums mainly explores the best O₂and CO₂atmosphere ratio by combining 1-MCP and CA atmosphere storage.The experimental results show that the combination of 1-MCP with CA air conditioning has better effect than use 1-MCP alone.It can effectively reduce the rotten fruit rate of green and brittle plums,maintain its hardness,and increase the total soluble solids(TSS).Keep the contents's stability of titratable acid(TA),and both have significant changes(p<0.05).In addition,1-MCP conbined with CA storage can effectively inhibit the activities of PG,SAI and SS-I's enzyme activity in the green crisp plum fruit,effectively prevent the fruit become softer,contorl the decline of soluble sugar content in the fruit,and keep the storage quality better.On the whole,the hypoxic group(2%O₂+10%CO₂+88%N₂)modified atmosphere combined with 1-MCP has the best effect on the preservation of green crisp plums...