The High CO₂ Induced Core Browning And Its Related Mechanism In 'Yali' Pear

This thesis utilized controlled atmosphere storage technology and used pears as experimental material to study sensibility to high CO₂ stress damage in the process of storage after pears had been picked.The experiment designed four experimental groups,i.e.,8%O2 +0%,0.5%,1%and 3%CO₂,to study impacts of different CO₂ concentrations on quality and cores' brown stain when pears are stored.1.Controlled atmosphere storage in different CO₂ concentrations has different effects on quality of pears.During storage,hardness of pears slowly decreases with increasing storage time.controlled atmosphere storage conditions with 0%and 0.5%CO₂ concentrations are beneficial to maintain hardness of pears.In terms of consumption of breath substrates,the content of soluble solids and titratable acid increases first and then decreases.Treatment with CO₂ in different concentrations has inhibiting effect on consumption of titratable acid in substrate and promoting effect on consumption of soluble solids.The content of vitamin C constantly decreases with the storage time and slightly influenced by CO₂ in different concentrations.2.Different CO₂ concentrations could affect generation of brown stain at cores of pears.The higher the CO₂ concentration was,the higher the index that brown stain might occur at cores of pears would be.Content of phenolic substance in cores of pears had significant relationship with occurrence of cores' brown strain.As phenols substrate related to occurrence of cores' brown strain,arbutin and chlorogenic acid's content in the core reduced constantly in the process of storage,while the index of cores' brown strain increased continuously.3.In controlled atmosphere storage process,the storage environment with high CO₂ concentration inhibits decomposing of sugar in pears.The content of glucose and fructose is obviously inhibited when compared with the air control group.Sorbitol is not sensitive to the environment in different CO₂ concentrations.4.Treatment with CO₂ in different concentrations prolongs the appearance of energy charge peak in pears.High-concentrated CO₂ in the storage environment inhibits energy transformation in the pears' metabolic process,which proves that air conditioned storage with high-concentrated CO₂ reduces energy transfer in pears and that it is unbeneficial for normal metabolism.