Mechanism Of Mechanical Damage On Apple

In this thesis,'gala' apple was used as a test material to study the effect of static pressure damage caused by stacking on fruit quality and the fruit damage of the control group after treatment with chitosan(30%ethanol + 1%chitosan).The closeness of the indicator to determine the regulation effect of chitosan on the fruit,to provide theoretical guidance for production practices.Research indicates:The mechanical damage resulted in a decrease in the hardness of apple fruits stored during shelf life,a decrease in titratable acid and soluble solids content,an increase in the degree of fruit browning,and a mechanical damage that disrupted the balance between the production and clearance systems of reactive oxygen species in the cells and resulted in the MDA content of the fruits.The content of H2O2 and the activities of CAT,POD and SOD increased,and the quality of damaged apple was significantly lower than that of the control(P<0.05),After treatment with chitosan,mechanically damaged fruits slowed down the speed of fruit hardness caused by mechanical damage,maintained SSC and TA content,reduced the increase in enzyme activity caused by mechanical damage,and in the late period of storage chitosan group The fruit hardness,SSC,and TA contents were basically the same as those in the control group.The activities of MDA,H2O2,POD,CAT and SOD were all superior to the control group.The mechanical damage caused the apple fruit cells to be squeezed,the cell gaps increased,the intercellular filaments of the fruit cell walls disappeared,the cells broke,and the normal breathing of the fruit and the energy metabolism environment were destroyed.The respiratory intensity of fruits was significantly increased after mechanical injury.The activity of phosphohexose isomerase,hexokinase,and fructose-6-phosphate kinase in the glycolytic pathway(EMP)was enhanced.The consumption of glucose in fruits and the accumulation of pyruvic acid increased.The chitosan treatment formed a layer of film on the mechanically damaged fruit surface,which slowed down the respiration rate caused by the mechanical damage of the fruit,slowed down the process of fruit's respiratory metabolism,and slowed down the quality.Mechanical damage destroys the cell structure of the fruit,leading to increased cell membrane permeability,decreased energy synthesis of the fruit,mechanical damage resulting in a brief increase in AMP,ADP,ATP,EC content and H+-ATPase,Ca2+-ATPase,and COO enzyme activity in fruits.drop rapidly.The energy metabolism of apple fruit damaged by chitosan treatment was higher than that of the damaged group,which was close to the control group and played a significant role in regulation.The 'gala' apple esters accounted for 67%to 72%of the total aroma components,which can be judged as ester-flavored fruits.In the early stage of storage,the speed of the ester material in the damaged group accelerated,and after the chitosan treatment,the aroma components of the chitosan group were significantly higher than the mechanical damage group in the late storage period,and were superior to the control group,and had aroma substances.Very good retention effect.The chitosan coating treatment of mechanical damage apple changes the speed of the fruit quality,has a very obvious regulation effect on the fruit deterioration caused by mechanical damage.