Zhou Molin, Ndeurumio Kessy H, Zhao Lei, Hu Zhuoyan
College of Food Science, South China Agricultural University , Guangzhou 510642, People's Republic of China.
J Agric Food Chem. 2016 Aug 24;64(33):6443-50. doi: 10.1021/acs.jafc.6b01738. Epub 2016 Aug 12.
Longan (Dimocarpus longan Lour.) fruit cultivars 'Chuliang' and 'Shixia' were analyzed for γ-aminobutyric acid (GABA) accumulation after precooling and in controlled-atmosphere storage. Fruit were exposed to 5% O2 plus 3%, 5%, or 10% CO2 at 4 °C, and GABA and associated enzymes, aril firmness, and pericarp color were measured. Aril softening and pericarp browning were delayed by 5% CO2 + 5% O2. GABA concentrations and glutamate decarboxylase (GAD; EC 4.1.1.15) activities declined during storage at the higher-CO2 treatments. However, GABA aminotransferase (GABA-T; EC 2.6.1.19) activities in elevated CO2-treated fruit fluctuated during storage. GABA concentrations increased after precooling treatments. GAD activity and GABA-T activity were different between cultivars after precooling. GABA concentrations in fruit increased after 3 days of 10% CO2 + 5% O2 treatment and then declined as storage time increased. GABA accumulation was associated with stimulation of GAD activity rather than inhibition of GABA-T activity.
对龙眼（Dimocarpus longan Lour.）品种‘储良’和‘石硖’在预冷后以及气调贮藏期间的γ-氨基丁酸（GABA）积累情况进行了分析。果实置于4℃、5%氧气加3%、5%或10%二氧化碳的环境中，测定了GABA及相关酶、果肉硬度和果皮颜色。5%二氧化碳+5%氧气延缓了果肉软化和果皮褐变。在较高二氧化碳处理的贮藏期间，GABA浓度和谷氨酸脱羧酶（GAD；EC 4.1.1.15）活性下降。然而，高二氧化碳处理果实中的GABA转氨酶（GABA-T；EC 2.6.1.19）活性在贮藏期间波动。预冷处理后GABA浓度增加。预冷后不同品种间GAD活性和GABA-T活性存在差异。10%二氧化碳+5%氧气处理3天后果实中GABA浓度增加，随后随着贮藏时间延长而下降。GABA积累与GAD活性的刺激有关，而非GABA-T活性的抑制。
