高CO_2结合低O_2贮藏对杏鲍菇谷氨酸代谢的影响

Effects of Storage in High Carbon Dioxide and Low Oxygen on Glutamic Acid Metabolism in Pleurotus eryngii

谷氨酸属于杏鲍菇中的鲜味氨基酸,为探讨高CO_2结合低O_2贮藏对杏鲍菇谷氨酸代谢的影响,以空气气体比例为对照(CK),用不同的气体组分[CA1(2%O_2)、CA2(2%O_2+10%CO_2)、CA3(2%O_2+30%CO_2)、CA4(2%O_2+50%CO2)]对杏鲍菇进行气调处理,研究了贮藏期间菇体丙二醛含量及抗氧化酶活性的变化,结合聚类分析表明CA3(2%O_2+30%CO_2)处理对减缓采后杏鲍菇的衰老具有重要的作用。进一步分析了CA3处理对杏鲍菇表型、呼吸速率、游离氨基酸含量、味觉变化及蛋白酶、谷氨酸合酶(GOGAT)、脯氨酸脱氢酶(PRODH)和谷氨酸脱氢酶(GDH)活性的影响。结果表明,较对照相比,CA3处理降低了采后杏鲍菇的呼吸速率,增加了其总游离氨基酸及谷氨酸含量,从而维持了菇体的滋味品质;另外,该CA3处理抑制了采后杏鲍菇蛋白酶、GOGAT、PRODH和GDH的活性。可见,2%O_2+30%CO_2贮藏可维持采后杏鲍菇的鲜味特征,该作用与其抑制GDH的活性有关。

Glutamic acid is a flavorful amino acid in Pleurotus eryngii. To explore the effect of high carbon dioxide and low oxygen storage on glutamic acid metabolism in Pleurotus eryngii postharvest, samples were stored in a controlled atmosphere using different gas compositions（CA1（2% O_2）, CA2（2% O_2 ＋ 10% CO_2）, CA3（2% O_2 ＋ 30% CO_2）, CA4（2% O_2 ＋ 50% CO_2）, and a normal air gas ratio was used as the control（CK, 20.9% O_2 ＋ 0.04% CO_2）. The malondialdehyde content and antioxidant activity of Pleurotus eryngii were studied over time in storage. The results in combination with clustering analysis showed that CA3（2% O_2 ＋ 30% CO_2） treatment played an important role in alleviating the senescence of Pleurotus eryngii postharvest. The effects of CA3 treatment on the phenotype, respiration rate, free amino acid content, and taste change, as well as the activities of protease, glutamate synthase（GOGAT）, proline dehydrogenase（PRODH）, and glutamate dehydrogenase（GDH） in Pleurotus eryngii were analyzed. The results indicated that compared with the control, CA3 treatment decreased the respiration rate and increased the content of total free amino acids and glutamic acid, thereby maintaining the taste characteristics. In addition, CA3 treatment inhibited the activities of protease, GOGAT, PRODH, and GDH. Therefore, storage at 2% O_2 ＋ 30% CO_2 could maintain the umami characteristics of Pleurotus eryngii postharvest, and this effect is associated with the inhibition of GDH activity.