γ-氨基丁酸对黄秋葵采后品质及生理特性的影响

为研究γ-氨基丁酸(γ-aminobutyric acid,GABA)处理对采后秋葵常温贮藏品质及生理特性的影响,分别用不同浓度(5、10、15 mmol/L)GABA水溶液浸泡黄秋葵3 min,以清水处理为对照,室温下(25℃)贮藏,并定期测定黄秋葵贮藏过程中失重率、叶绿素、V_C含量、丙二醛含量、抗氧化酶活性等生理指标的变化。结果表明,10 mmol/L的GABA处理效果最好,能够明显减缓黄秋葵的采后失水,延缓叶绿素和V_C的降解,能明显提高过氧化氢酶(Catalase,CAT)和超氧化物歧化酶(Superoxide dismutase,SOD)活性,降低过氧化物酶(Peroxidase,POD)活性和减少丙二醛(Malondialdehyde,MDA)的积累。其中贮藏21 d的叶绿素含量比对照组(0.074 mg/g)高出37.49%,V_C含量比对照组(3.61 mg/100 g)提高了69.23%,SOD活性相比对照组(47.05 U/g)提高了30.35%。相关性和主成分分析表明,黄秋葵贮藏时间和失重率、MDA含量呈极显著正相关(P<0.01),与叶绿素含量、V_C含量、CAT活性和POD活性呈极显著负相关(P<0.01);黄秋葵贮藏品质和综合评价指数均随贮藏时间增加而逐渐降低,而不同浓度的GABA处理能延缓黄秋葵贮藏品质的下降。这些结果表明适宜浓度的GABA处理可以延缓黄秋葵果荚的采后衰老,并保持良好的采后品质和营养价值,为GABA的应用及黄秋葵的采后保鲜提供理论依据。

Effect of GABA on the Quality and Physiological Characteristics of Postharvest Okra

In order to study effects of γ-aminobutyric acid( GABA) treatment on the storage quality and physiological characteristics of post-harvested okra at room temperature,the okra was treated with different concentrations( 5,10,15 mmol/L)of GABA for 3 min and then was stored at room temperature( 25 ℃),and water treatment group was used as a control. All physiological indexes such as weight loss rate,chlorophyll,VCand malondialdehyde content and antioxidant enzyme activity were regularly determined.The results showed that 10 mmol/L GABA treatment showed the best preserving effects,which could significantly reduce the post-harvest water loss of okra,delay the degradation of chlorophyll and VC,significantly increase catalase( CAT) activity and superoxide dismutase( SOD) activity,decrease peroxidase( POD) activity and accumulation of malondialdehyde( MDA). Chlorophyll content at 21 d was 37.49% higher than that of the control group( 0.074 mg/g),VC content was 69.23% higher than that of the control group( 3.61 mg/100 g) and SOD activity was 30.35% higher than that of the control group( 47.05 U/g). Correlation and principal component analysis( PCA) showed that weight loss rate and MDA were positively correlated with storage time of okra( P < 0.01),while chlorophyll content,VCcontent,POD activity and CAT activity were negatively correlated with storage time( P < 0.01). The storage quality and comprehensive evaluation index of okra decreased gradually with storage time,different concentration of GABA treatment could delay the decline of okra storage quality.The results suggest that appropriate concentration of GABA treatment can delay the postharvest senescence of okra pod and maintain the good postharvest quality and nutritional value of okra,which provides a new theoretical basis for the application of GABA and post-harvest preservation of okra.