Effects Of Mechanical Damage On Postharvest Physiology And Biochemistry Of Dangshan Pear

DangShan peer is well-known all of the world of its long history and the place of local varieties. Because of the peer is crisp and content high moisture, when in transportation will lead to mechanical damage inevitably, So lead the commodity value and food quality decline. In domestic and foreign countries the research about DangShan peer are mainly concentrated in how to storage, the research about mechanical damage will cause physiological and biochemical changes have not been reports. This experiment made the method of the mechanical damage by artificial simulation, choosing two different damage degrees and stored in two different temperature conditions, Do the research about physiological and biochemical changes in injured area fruits, In order to depth understanding the science of the physiological and biochemical reaction mechanism after the mechanical damage, provide theoretical basis for postharvest fruits and vegetables how to better storage and transport. The results show that:1．The mechanical damage can obviously induce the generation of ethylene which are injuries, the releases significant high than control. When damage more serious, the release of ethylene more higher, and the peak of release came early. Low temperature storage can significantly inhibit the ethylene release, and prevent injury fruit aging rapidly.2．The mechanical damage made the fruit respiration rate significantly increased, the soluble solids content gradually decline, fruit firmness decreased, and when injuried more seriously, storage temperature more higher, the changing trends more obvious. In the whole storage process, the wounds fruit physiological indexes has experienced repeated rise and fall process. When storage at low temperature, the change trend gently. The wounds fruit storage at18℃emerge breathing two peak times, the second lower than the first. Injury fruit acid content greatly decreased, small amplitude in later time.In the early time the content of Vc maintain higher but later generally decline.When storage in higher temperature,the mechanical damage more serious, the nourishment composition decline more quickly.3．The mechanical damage cause injury fruit cellulose enzyme activity, PAL activity and SOD activity obviously lower than contrast. In the storage period each index showed the repeated process extension of the different level of rise and fall. The cellulose enzyme activity gradually decline in two different kinds of storage temperature, In the18℃the PAL activity gradually rise in early time storage, but decline slow in later time, When storage in3℃the up and down change obviously. In3℃storage the SOD activity keep in high levels, So the postharvest DangShan peer storage at low temperature also have stronge antioxidant ability. When the mechanical damage more serious, the storage temperature more higher, the enzymes changed more faster. Low temperature significantly inhibit enzymes activity.4．When storage at two kinds of temperature the PPO activity and POD activity in injuried fruit rises in the early time but late downward. When storage at3℃, in early time the PPO activity in hurt part slightly higher than the control, storage in low temperature the PPO activity lower at end. The POD activity in injuried fruit high than controlled when storage at two different temperature. In all storage time, the POD activity repeated rise and fall process. In low temperature the POD activity changes relatively slow. The POD activity increased with the mechanical damage, when mechanical damage more seriously, the POD activity more higher.