荔枝采后极易发生果皮褐变，为研究外源γ-氨基丁酸（GABA）处理对荔枝果皮褐变及酚类物质变化的影响，采用5 mmol/L的GABA溶液浸泡处理荔枝15 min，于（20±1）℃下贮藏6 d，定期取样进行果皮褐变及酚类 物质相关生理指标测定。结果表明：GABA处理可以有效延缓荔枝果皮褐变，5 mmol/L GABA处理的荔枝在20 ℃下贮藏6 d后褐变指数为2.80，显著低于对照组（3.60），同时好果率达36.67%，失重率仅为3.82%。在贮藏期间，GABA处理显著减少荔枝果皮中丙二醛（MDA）积累，抑制多酚氧化酶（PPO），过氧化物酶（POD）和漆酶（LAC）活力，激活苯丙氨酸解氨酶（PAL），贮藏6 d时GABA处理的荔枝果皮具有较高的总酚（525.93 mg GA/g）、黄酮（14.06 mg rutin/g）和花色苷（0.54 ∆A/g）物质积累，果皮DPPH自由基清除能力提高。实验结果说明，5 mmol/L GABA处理能抑制酶促褐变的发生，改变酚类物质代谢进程，从而延缓荔枝果皮褐变，改善荔枝采后贮藏品质。

Litchi fruit is prone to browning after harvest. To investigate the effects of exogenous γ-aminobutyric acid (GABA) on litchi pericarp browning and changes in phenolic compounds, litchi fruit was immersed in 5 mmol/L of GABA solution for 15 min and then stored at (20 ± 1) ℃ for 6 days. Samples were collected at regular intervals to measure the physiological indices related to pericarp browning and phenolic compounds. The results demonstrate that GABA treatment can significantly delay litchi pericarp browning. The browning index of litchi treated with 5 mmol/L of GABA was 2.80 after storage at 20 ℃ for 6 days, which was significantly lower than that of the control group (3.60). Meanwhile, the good fruit rate was 36.67%, and the weight loss rate was only 3.82%. During storage, GABA treatment significantly reduced the accumulation of MDA in the litchi pericarp and inhibited PPO, POD, and LAC activities while activating PAL. In addition, GABA-treated litchi pericarp showed higher total phenol (525.93 mg GA/g), flavonoid (14.06 mg rutin/g), and anthocyanin (0.54 ∆A/g) content after 6 days of storage. The DPPH free radical scavenging ability of the pericarp was also improved. In summary, 5 mmol/L GABA treatment can effectively delay litchi pericarp browning by inhibiting enzymatic browning and affecting phenolic metabolic processes, which is an effective method of improving litchi storage quality after harvest.

国家荔枝龙眼产业技术体系项目（CARS-32）；广州市科技计划重点项目（202103000054）