The Control And Mechanism Of Browning Heart Of The Huangguan Pears By 1-MCP Treatment

Browning heart is a physiological disorder occurs during the middle and late of Huangguan Pear storage. Late harvest is an important determinant of disease occurrence. Browning heart has become one of the bottlenecks affecting the development of the industry of Huangguan pear. So proven Huangguan pear core browning mechanism, looking for a suitable, effective and low cost solutions and control measures has important significance to promote the sustainable development and health of Huangguan pear industry. This study takes Jingtai Huangguan pear as test material, with 1.5?l·L-11- methylcyclopropene?1-MCP? processing, studies effects of 1-MCP treatment of different harvest period of Huangguan pear fruit core and flesh browning incidence, disease index, storage quality of fruit, ethylene release rate, respiratory intensity and with browning index?polyphenol oxidase?PPO?, peroxidase?POD? activity and total phenolic content?, and membrane lipid peroxidation index?superoxide dismutase?SOD? activity and hydrogen peroxide?H₂O₂?, malondialdehyde?MDA? content?, in order to clear the role of 1-MCP in Huangguan pear Brown heart disease control and reveal the mechanism of Huangguan pear Brown heart and the control mechanism of 1-MCP to Huangguan pear Browning heart, to provide a theoretical basis for the research and practice of 1-MCP control of Huangguan pear browning heart. Test results show that:1. The three harvest period of Huangguan pear had different degrees of core browning, and the flesh has no browning. Secondly, core browning and harvest period is closely related, harvest later, the browning occurred earlier of storage period, and the disease become more serious. Harvest stage III of Huangguan pear core onset after 4 months of cold storage and Harvest stage I and II onset after 8 months of cold storage. Refrigerate for 8 months, the fruit browning heart rate of harvest stage I was only 12.82%, and stage II and III were 48.72% and 56.41%. Moreover, 1-MCP treatment have obvious control effect on the browning heart of Huangguan pear, Refrigerated for 8 months, occurrence rate of core browning after 1-MCP treatment of stage I, II and III were reduced by 5%, 38% and 20% compared with the corresponding CK respectively, disease index also were decreased 25%, 39.2% and 54.6% compared with the corresponding CK respectively.2. The main reason of browning heart of Huangguan pear is enzymatic browning dominated by PPO. The main factor of browning heart occurs in the core and not in the flesh might be the physiological and biochemical metabolism in core is more active than the flesh. During the test, the activity of PPO, POD and total phenolics of three harvest period of Huangguan pear fruit core have significantly higher than corresponding flesh?p < 0.05?, average activity of PPO of harvest stage I, II and III fruit core are 1.70, 1.69 and 1.62 times compared with the corresponding flesh and the average activity of POD are 6.57, 5.95 and 5.42 times compared with the corresponding flesh respectively. The average content of total phenols respectively 2.32, 1.89 and 1.41 times compared with the corresponding flesh respectively.3. Browning heart of huangguan pear and membrane lipid peroxidation has close relationship, membrane lipid oxidation increased leads to the area distribution of phenolic compounds and phenolic enzymes is disrupted, the enzyme and substrate in contact with each other and then browning. During the test, average content of H₂O₂ and MDA and average activity of superoxide dismutase?SOD? were significantly higher than flesh?p < 0.05?, which is probably one of the reasons why the core occurs browning and flesh not. The average content of H₂O₂ and MDA of harvest period I, II and III are 5.14, 6.34, 8.25 times and 1.23,1.17,1.22 times of compared with the corresponding flesh respectively, the average activity of SOD is 1.81,2.43,2.99 times of compared with the corresponding flesh respectively. 1-MCP treatment can significantly reduce the accumulation of H₂O₂ and MDA, inhibit the activity of SOD of fruit core, In the fruit core of harvest period I, II and III After 1-MCP treatment, the peak value of H₂O₂ were reduced 54.25%, 14.06% and 40.21% compared with the corresponding CK respectively, refrigerated for 8 months, content of MDA were decreased 7.49%,25.96% and 25.98% compared with the corresponding CK respectively, during the whole storage period, the average activity of SOD of fruit core were reduced 11.1%, 4.9% and 12.5% compared with the corresponding CK respectively.4. 1-MCP treatment can significantly inhibit the respiration rate and ethylene release rate of Huangguan pear. Refrigerated for 6 months, respiration rate of Huangguan pear fruit after 1-MCP treatment were decreased 25.5%, 19.8% and 49.9% compared with the corresponding CK respectively. During the whole storage period, ethylene release rate of Huangguan pear fruit of harvest period I, II and III after 1-MCP treatment were dropped by an average of 22.6%, 22.3%, 21.4% compared with the corresponding CK respectively.5. 1-MCP treatment can effectively maintain the fruit hardness, soluble solids and titratable acid content of Huangguan pear. Fruit hardness of stage I, II and III after 1-MCP treatment were improved with the average 14.3%, 10.2%, 2.1% compared with the corresponding CK respectively. and the content of soluble solid improved by an average of 0.2, 0.45, 0.34 percentage point compared with the corresponding CK respectively, content of titration acid increased by 8.3%, 9.1% and 7.2% compared with the corresponding CK respectively.