Effect Of 1-MCP On Chilling Injury And Mechanical Damage Of Tomato Fruit

1-Methyleyelopropene(1-MCP) is a new ethylene action inhibitor.It was found that 1-MCP may inhibit the ethylene by strongly blocking ethylene binding and ethylene action to protect the fruit in postharvest(sisler,et al.1997).In this research,the effects of 1-MCP of different concentrations on chilling injury of tomatoes was evaluated.The mature-green tomatoes were treated with 1-MCP of 1μL/L,3μL/L,5μL/L for 6 hours.The first two weeks the tomatoes were in cold storage at 3℃,and then were placed in a 16-day storage at 20℃.A series of indexes closely realated to postharvest physilogy of tomato such as chilling injury index,disease incidence,hardness,peel color,ethylene production, lycopene content,titrated acidity(TA),soluble solid content(SSC),and the enzyme indexes such as the peroxidase(POD),polyphenol oxidase(PPO),catalase(CAT),Phenylalanine ammonia-lyase (PAL),β-1,3 glucanase(GLU),chitinase(CHI) were studied during the storage.The results showed that the chilling injury development of tomato was enhanced by 1-MCP and the disease incidence was aslo promoted.However,1-MCP had a positive role in maintaining some qualities of tomato,and those such as the decreasing of hardness and titrated acidity,the synthesis of lycopene were inhibited.1-MCP also delayed the onset of ethylene climacteric and increased the maximum value of ethylene production.And the activities of PPO and POD increased;the activity of CAT decreased;the increasing of activity of PAL and content of total phenol,the increasing of activities of GLU and CHI were inhibited.The effect of 1-MCP on tomatoes after mechanical damage were studied in this paper,too.The mechanical stress was simulated by making tomatoes fall from different heights of 0m,1m,1.5m. Then the mature-green tomatoes were treated with 1-MCP of 1μL/L for 6 hours.And the three groups of tomatoes were not treated with 1-MCP of the same mechanical damage were the control. At last the tomatoes were put in storage in room temperature.The index such as weight loss,peel color,hardness,ethlyne production,titrated acidity,soluble solid content,lycopene content,pectin and protopectin content,and the enzyme indexes such as the PPO,POD,CAT,PAL were studied during the storage.The results indicated that the tomatoes presented a series of physiological and biochemical changes which were not good to maintain the postharvest quality after mechanical damage.They released wound ethylene at a early time afer mechanical damge and brought forward the onset of ethylene climacteric,the weight loss increased,the decreasing of hardness was enhanced,the increasing of pectin content and the decreasing of protopectin content were enhanced,the decreasing of peel light and color change were accelarated,the synethesis of lycopene was accelarated,the decreasing of titrated acidity and the increasing of soluble solid content were enhanced,and the accumulation of MDA was accelarated.Moreover,the greater of the mechanical damage of tomatoes,the worse of the changes presented by the tomatoes.However,the tomatoes which were treated by 1-MCP delayed the bad physiological and biochemical changes.Compared to tomatoes of the same mechanical damage,the tomatoes treated with 1-MCP released less wound ethylene later and delayed the onset of ethylene climacteric;the weight loss decreased,the decreasing of hardness was more slowly,the increasing of pectin content and the decreasing of protopectin content were slowered,the decreasing of peel light and color change were slowered, the synethesis of lycopene was decelerated,the decreasing of titrated acidity and the increasing of soluble solid content were retarded,and the accumulation of MDA was slowerd.