| In this study,postharvest mushrooms(Pleurotus geesteranus)were treated with 0.5 ?L·L-1 and 10 ?L·L-1 1-methylcyclopropene(1-MCP)at 16.5 ± 0.5 ? and 93.0-98.4% RH for 3.0 h in 250 L closed plastic box.The quality indexes,energy status and umami taste of mushrooms were evaluated during storage at 5.0? for 9days.The results were as follows:1.The effects of 1-MCP on quality indexes of postharvest mushrooms.Samples treated with 1-MCP showed higher weight loss,electrolyte leakage,MDA contents and respiration rate,while lower firmness,ethylene production peak.The results indicated that the membrane lipid peroxidation and permeability increased.The effects of 1-MCP on respiration and ethylene weakened with the increase of storage time.There was no significant difference between the 0.5 ?L/L and 10 ?L/L treatment.2.The effects of 1-MCP on energy level,energy metabolism-related enzymes activities of postharvest mushrooms.Samples treated with 1-MCP showed lower ATP and ADP contents,while higher ADP contents and energy charge.In the late storage,the activities of phosphofructokinase,citrate synthase,?-ketoglutarate dehydrogenase,and 6-phosphate dehydrogenase increased,which indicated that EMP,TCA and pentose phosphate pathway accelerated,more ATP,reducing power and raw materials for biosynthesis such as ribose 5-phosphate.3.The effects of 1-MCP on umami taste of postharvest mushrooms.The umami amino acid contents of 1-MCP treated mushrooms were significantly lower than that of CK(day 1).Arginine showed the highest content among all amino acids.GMP content was significantly higher than the contents of IMP and XMP.The contents of 5?-nucleotides increased first and then decreased.The contents of 5?-nucleotides,EUC value and sensory score(electronic tongue)of 1-MCP treated samples were lower than that of Control group.4.Correlation analysis showed that there was significant positive correlation between energy substance and the umami competents of Pleurotus geesteranus.The correlation coefficient between EUC and sensory analysis(electronic tongue)was low,therefore,there was no consistency between them.In summary,1-MCP treatment lower umami taste and quality of mushrooms by accelerating energy metabolism rate.Besides,the significant physiological changes at 7 – 9 days storage would be the characteristic phenomenon of reaching the end of shelf life. |
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