石榴果实发育期果皮褐变及相关酶活性变化

为探明石榴果实发育期果皮褐变及其相关酶活性、总酚和抗氧化能力的变化规律及相互关系,以泰山红和泰山三白甜石榴为试材,研究各发育期果皮褐变度、多酚氧化酶(PPO)活性、过氧化物酶(POD)活性、苯丙氨酸解氨酶(PAL)活性、总酚含量和DPPH自由基清除率的变化。结果表明,2个品种果皮褐变度、PPO活性、POD活性、总酚含量和DPPH自由基清除率随着发育天数的增加逐渐降低,均在7月15日达到最高。2个品种果实发育期果皮PAL活性呈先降低后升高再降低的变化趋势,分别在7月15日和9月13日出现峰值。泰山红抗褐变能力高于泰山三白甜,二者分别在9月23日和9月13日采收能减轻褐变的发生。相关性分析表明,PAL、PPO、POD、总酚和DPPH自由基清除率均与石榴果实酶促褐变密切相关,石榴果实酚类物质含量高低与其抗氧化能力极显著正相关。本研究结果为深入揭示石榴果实褐变机理提供了理论依据。

Changes of Browning and Its Related Enzyme Activities in Pomegranate Peel During Fruit Development Period

To explore the change regularity and interrelationship of fruit peel browning and its related enzyme activities,total phenols and antioxidant capacity during development period,Taishanhong and Tanshansanbaitian pomegranate were employed as the experiment materials to study the changes of browning degree,activity of polyphenol oxidase (PPO),peroxidase (POD) and phenylalanine ammonialyase (PAL),total phenols content,1,1-diphenyl-2-picrylhydrazyl (DPPH) radial scavenging rate.The results showed that the browning degree,activity of PPO and POD,total phenols content,DPPH radial scavenging rate of two pomegranate cultivars decreased gradually with increasing of development days.The peak value of above indexes all appeared on July 15th.The variation tendency of phenylalanine ammonialyase (PAL) activity of two pomegranate cultivars decreased firstly and increased subsequently,then decreased with development.The peak value of PAL activity presented on July 15th and September 13th.The anti-browning ability of Taishanhong fruit was higher than that of Tanshansanbaitian.The harvest time of Taishanhong and Tanshansanbaitian was September 23th and September 13th,respectively,which could reduce the occurrence of browning.Correlation analysis showed that PAL,PPO,POD,total phenols and DPPH radical scavenging rate were closely related to enzymatic browning of pomegranate fruit.There was significant positive correlation between total phenols content and DPPH radical scavenging rate.The results in this present study provided a theoretical basis for further revealing the browning mechanism of pomegranate fruit.