臭氧水对荔枝采后若干生理生化指标的影响

用不同浓度臭氧水对荔枝果实进行采后处理,测定其花色素苷、类黄酮、可滴定酸和糖含量以及多酚氧化酶和过氧化物酶活性。结果显示,处理后荔枝果皮中花色素苷、类黄酮含量下降速度低于对照,PPO活性低于对照,POD活性高于对照,而果汁中可滴定酸及糖含量与对照相比无显著变化。表明一定浓度臭氧水对荔枝果实保色护色有一定效果,并有防褐变作用。     

防止速冻荔枝果皮变褐的研究

荔枝(Litchi chinensis Sonn.)果实采收后容易变褐变质。三年来,我们研究了荔枝果皮的多酚氧化酶与变褐的关系以及防止速冻荔枝果皮变褐的各种枝术措施。证明:荔枝果皮中具有氧化邻苯二酚的多酚氧化酶,在果皮褐变过程中该酶起着重要的作用,采用热处理及化学药物处理能抑制多酚氧化酶活性,达到防止速冻荔枝果皮变褐的目的。     

荔枝果皮过氧化酶的纯化与性质研究(英)

荔枝果皮采后褐变是影响这一重要热带水果经济价值的主要问题,酚类物质的酶促氧化一直被认为是造成植物组织褐变的关键因素,其中多酚氧化酶被研究得最多.过氧化物酶在植物体中分布很广,能够氧化多种底物,在荔枝果皮中的含量也很高.非结合性过氧化物酶已经被证明在果实的采后成熟与老化过程中参与多种过程.在这项研究中,用磷酸缓冲液提取荔枝果皮的非结合性过氧化物酶,并通过硫酸铵沉淀,DEAE Sephadex A-50离子交换柱层析以及Sephadex G-100凝胶过滤进行纯化.对得到的酶溶液进行了酶学性质的研究,发现荔枝果皮过氧化物酶具有较高的热稳定性和高的最适反应pH值（6.8）,能够氧化许多底物尤其是单酚和各种多酚类物质,反应抑制剂专一性与其他植物来源的过氧化物酶略有不同.显示了过氧化物酶参与荔枝果皮褐变过程的可能性,并为提高荔枝采后贮藏性提供了新的思路.     

荔枝果皮过氧化酶的纯化与性质研究

荔枝果皮采后褐变是影响这一重要热带水果经济价值的主要问题,酚类物质的酶促氧化一直被认为是造成植物组织褐变的关键因素,其中多酚氧化酶被研究得最多.过氧化物酶在植物体中分布很广,能够氧化多种底物,在荔枝果皮中的含量也很高.非结合性过氧化物酶已经被证明在果实的采后成熟与老化过程中参与多种过程.在这项研究中,用磷酸缓冲液提取荔枝果皮的非结合性过氧化物酶,并通过硫酸铵沉淀,DEAFSephadex A-50离子交换柱层析以及Sephadex G-100凝胶过滤进行纯化.对得到的酶溶液进行了酶学性质的研究,发现荔枝果皮过氧化物酶具有较高的热稳定性和高的最适反应pH值(6.8),能够氧化许多底物尤其是单酚和各种多酚类物质,反应抑制剂专一性与其他植物来源的过氧化物酶略有不同显示了过氧化物酶参与荔枝果皮褐变过程的可能性,并为提高荔枝采后贮藏性提供了新的思路.     

O2和CO2配比对气调贮藏梨采后褐变及相关理化因子的影响

以采后'丰水'梨果实为材料,在乐扣气调试验箱中研究了O2和CO2配比对果实褐变率、多酚氧化酶(PPO)和过氧化物酶(POD)活性、丙二醛(MDA)和总酚含量的影响,以探讨适宜减轻梨气藏褐变的气体成份.结果表明:在整个贮藏过程(150 d)中,'丰水'梨果肉未发生褐变.从贮藏60 d开始,气调处理和冷藏对照果实的果皮均出现褐变,气调处理在贮藏120 d之前对果皮褐变的影响不显著,而在贮藏120～150 d内可显著减轻果皮的褐变、抑制果皮PPO和POD活性及降低总酚含量.与冷藏对照相比,气调处理可推迟果心褐变的时间,且(8%～10%)O2+3% CO2处理可完全抑制果心的褐变;气调处理亦可降低果心PPO活性、减少总酚及MDA含量;(8%～10%)O2+1% CO2处理能够显著提高果心的POD活性,而(8%～10%)O2+3% CO2处理对果实POD活性的影响不显著.可见,气调贮藏主要是通过降低'丰水'梨果皮PPO、POD活性及总酚含量来减轻组织的褐变,并以(8%～10%)O2+3% CO2处理对果实褐变因子的控制效果较理想.     

采后荔枝果皮色素、总酚及有关酶活性的变化

成熟度约八成的“淮枝”在采收后2天内,色素的合成代谢仍相当活跃,类胡萝卜素,花色素苷的含量增高,多酚氧化酶和苯丙氨酸解氨酶的活性增大,总酚保持原有水平,叶绿素降解,反映了果实达到完全成熟的特征,随后,上述各项参数因果实的衰老而下降,与采收当天相比,7天后花色素苷为90％,类黄酮为59％,总酚为71％,苯丙氨酸解氨酶活性为46％,讨论了酚类,花色素苷及两种酶活性之间的关系及对荔枝果实在成熟,衰老褐变中的作用。     

采后荔枝果皮色素、总酚及有关酶活性的变化

成熟度约八成的“淮枝”在采收后2天内,色素的合成代谢仍相当活跃,类胡萝卜素,花色素苷的含量增高,多酚氧化酶和苯丙氨酸解氨酶的活性增大,总酚保持原有水平,叶绿素降解,反映了果实达到完全成熟的特征,随后,上述各项参数因果实的衰老而下降,与采收当天相比,7天后花色素苷为90％,类黄酮为59％,总酚为71％,苯丙氨酸解氨酶活性为46％,讨论了酚类,花色素苷及两种酶活性之间的关系及对荔枝果实在成熟,衰老褐变中的作用。     

丁香精油对冷藏冬枣果实腐烂及诱导抗病相关酶活性的影响

对不同浓度丁香精油处理冬枣果实在0℃贮藏期间(60d)及藏后25℃货架期(5d)的果实腐烂率、诱导抗病相关酶活性和总酚含量的变化特征进行分析,以探索丁香精油抑制冬枣果实腐烂与抗病性诱导的关系。结果表明:丁香精油处理能有效抑制冬枣贮藏期果实腐烂的发生,提高其苯丙氨酸解氨酶、多酚氧化酶和过氧化物酶活性,诱导总酚含量的增加。经丁香精油处理冬枣果实在贮藏60d后25℃货架期5d时的腐烂指数得到明显下降,同时保持了较高的苯丙氨酸解氨酶、多酚氧化酶、过氧化物酶活性和总酚含量,并以0.50%丁香精油处理的效果最显著,其贮藏后货架期的果实腐烂指数较对照下降了45.5%。可见,丁香精油抑制贮藏冬枣果实的腐烂与抗病相关酶活性的升高密切相关,抗病性诱导是丁香精油处理抑制冬枣采后果实腐烂的重要原因之一。     

荔枝果实在发育和采后的乙烯产生及其生理作用

荔枝果实在发育与成熟过程中呼吸作用和乙烯的产生不断下降。 成熟荔枝果皮的乙烯产生量约为果肉和种子的86倍。外源乙烯处理能提高荔枝果皮多酚氧化酶和过氧化物酶活性。 在5℃下,荔枝果实的呼吸和乙烯产生受到强烈抑制,只有常温(25℃)下的1/10或更低,但进入常温后则很快上升,果实内部乙烯最高可达17.6 ppm。     

温度对采后石榴果实品质和某些生理指标的影响

研究不同温度对采后石榴品种‘净皮甜’果实品质和某些生理指标影响的结果表明：在5℃条件下贮藏的石榴,其果实中可溶性固形物含量、总糖含量和可滴定酸含量可以得到保持,果皮的相对电导率和褐变指数升高速率减慢,果实的呼吸速率和腐烂率下降,抗坏血酸氧化酶（AAO）和多酚氧化酶（PPO）活性受到抑制,过氧化物酶（POD）和过氧化氢酶（CAT）活性保持相对较高水平。贮藏120d的果实品质良好,保鲜效果也较好。     

龙眼果实采后失水果皮褐变与活性氧及酚类代谢的关系

研究了(10±1)℃和50%相对湿度贮藏条件下"福眼"龙眼果实果皮褐变与活性氧和酚类代谢的关系.结果表明,采后失水导致龙眼果实果皮褐变,果皮活性氧清除酶SOD、CAT、APX、GR活性和内源抗氧化物质AsA、GSH含量下降,O-2产生速率和MDA含量增加,细胞膜透性迅速增大;PPO和POD活性增加,总酚和类黄酮含量明显下降.据此认为,果皮褐变可能是细胞的活性氧代谢失调,细胞膜结构破坏,使PPO、POD与酚类物质(含类黄酮)接触、酚类物质氧化的结果.     

The Changes of Pigments,Phenolics Contents and Activities of Polyphenol Oxidase and Phenylalanine Ammonia-Lyase in Pericarp of Postharvest Litchi Fruit

A common litchi cultivar “Huaizhi” was used for the experiment to understand the changes of pigment, phenolics content and activities of two enzymes involing in phenolics metabolism in pericarp during storage at room temperature and relative humidity of 73–79%. The maturation of "Huaizhi" fruit was 80% when harvested. The contents of carotenoid, anthocynin and activities of phenylalanine ammonia-lyase, polyphenol oxidase were increased, and the content of total phenolics was kept at its initial level in the first 2 days of storage. It indicated that the active synthesis of pigments and phenolics still continued with the progressive ripening. A decline of above parameters and content of flavonoid ware observed during the senescence of fruit. The relative contents of anthocynin, flavonoid, phenolics and activity of phenylalanine ammonialyase were 90%, 59%,71% and 46% in the day of 7 compared with that when harvested, respectively. Less change of anthocynin content was found in browning pericarp. The relation between phenolics, anthocynin and activities of two enzymes during repining and senescence of litchi fruit was discussed.     

钙处理对红富士苹果酶促褐变的影响

渗钙处理能够明显保持红富士苹果的硬度,且褐变度明显低于对照,渗钙对酶促褐变的抑制作用是通过影响PPO活性和LOX活性起作用的,果实褐变的早期发动与LOX活性相关密切,后期褐变则主要是PPO起作用。     

沙藏、维生素C和亚硫酸氢钠对薯蓣块茎贮藏期间褐变的影响

沙藏、维生素C和亚硫酸氢钠（NaHSO3）处理的薯蓣,贮藏前期多酚氧化酶活性的上升速度低于而后期酶活性下降速度则高于不作处理的,与后期这3种处理的褐变度几乎不上升相一致。各处理的过氧化物酶活性变化差异大,但与褐变度的关系不大。超氧化物歧化酶活性均呈先升后降趋势,各处理中酶活性的下降速度均低于不作处理的。丙二醛含量均呈持续上升趋势,不作处理的高于处理的。在防止或削弱贮藏期间薯蓣褐变的处理中,以沙藏和NaHSO3处理的效果较好。     

炭疽病菌侵染对荔枝果实生理生化变化的影响

本研究测定了荔枝果实人工接种炭疽病菌后呼吸速率、乙烯释放量的变化和果皮氧化、过氧化作用以及与酚类代谢有关的几种酶活性的变化。结果表明,接种炭疽病菌的荔枝果实呼吸速率和乙烯释放量显著增高,果皮活性氧(O₂^·)产生速率和丙二醛(MDA)含量显著增加,超氧化物歧化酶(SOD)活性显著降低,过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性显著增高。说明炭疽病菌的侵染可导致荔枝果实呼吸速率和乙烯释放量的增高,加速荔枝果皮氧化和过氧化进程,并诱导荔枝果皮PPO、POD、PAL活性增高,是加速采收后荔枝果实衰老、褐变、腐烂的一个重要原因。     

Polyphenol gene expression and changes in anthocyanins and polyphenols in the skin of ‘Braeburn’ apples after the autumn application of prohexadione-calcium

Prohexadione-calcium (Pro-Ca) transient inhibits 2-Oxoglutarate-dependent dioxygenases and causes significant changes in the flavonoid spectrum of apple. In the present study the influence of two autumn preharvest applications of Pro-Ca on the polyphenol metabolism in apple peel during the advanced maturation was investigated. Pro-Ca was sprayed in two doses, approximately five and 3 weeks before the technological maturity. Changes in the concentrations of hydroxycinnamic acids, dihydrochalcones, flavonols, flavanols and anthocyanins as well as their related gene expression and enzyme activities in the apple peel were monitored six times during the advanced maturation until the technological maturity of the fruits. To evaluate its influence on red coloration differences in the chromatic values a*, h° and L* between the treated and untreated apples were monitored. The parameters showed a temporary effect of Pro-Ca on the intensity of red coloration, which was not detected anymore at the technological maturity of apples. The application of Pro-Ca decreased the flavanone 3-hydroxylase activity and slightly inhibited activities of all the enzymes analyzed. Concomitantly, the concentrations of anthocyanins in the peel of the treated apples decreased, whereas the concentrations of hydroxycinnamic acids, dihydrochalcones and flavan 3-ols increased. Flavonol concentrations, however, remained unchanged. The expression of ANS, ANR, FGT and MYB10 was downregulated after the Pro-Ca treatment. The results indicate that the autumn application of Pro-Ca modulates the biosynthetic pathway resulting in distinct changes in the flavonoid composition in the apple peel of ‘Braeburn’ apples. However, the changes are temporary and are generally suspended during apple storage.     

花色苷的酶降解

综述了降解花色苷的酶类及其降解机理的研究进展.降解花色苷的酶有花色苷酶、多酚氧化酶、过氧化物酶和果胶酶.花色苷酶和果胶酶均能水解花色苷糖苷键产生花色素和糖,花色素很不稳定,因吡喃烊环极易开环可自发转换成无色衍生物.花色苷不能直接作为PPO或POD的底物;PPO和POD氧化、降解花色苷须依赖具邻二酚结构的其他酚类的存在,...     

Cloning and Expression Analysis of Litchi (Litchi Chinensis Sonn.) Polyphenol Oxidase Gene and Relationship with Postharvest Pericarp Browning

Polyphenol oxidase (PPO) plays a key role in the postharvest pericarp browning of litchi fruit, but its underlying mechanism remains unclear. In this study, we cloned the litchi PPO gene (LcPPO, {"type":"entrez-nucleotide","attrs":{"text":"JF926153","term_id":"350601663","term_text":"JF926153"}}JF926153), and described its expression patterns. The LcPPO cDNA sequence was 2120 bps in length with an open reading frame (ORF) of 1800 bps. The ORF encoded a polypeptide with 599 amino acid residues, sharing high similarities with other plant PPO. The DNA sequence of the ORF contained a 215-bp intron. After carrying out quantitative RT-PCR, we proved that the LcPPO expression was tissue-specific, exhibiting the highest level in the flower and leaf. In the pericarp of newly-harvested litchi fruits, the LcPPO expression level was relatively high compared with developing fruits. Regardless of the litchi cultivar and treatment conditions, the LcPPO expression level and the PPO activity in pericarp of postharvest fruits exhibited the similar variations. When the fruits were stored at room temperature without packaging, all the pericarp browning index, PPO activity and the LcPPO expression level of litchi pericarps were reaching the highest in Nandaowuhe (the most rapid browning cultivar), but the lowest in Ziniangxi (the slowest browning cultivar) within 2 d postharvest. Preserving the fruits of Feizixiao in 0.2-μm plastic bag at room temperature would decrease the rate of pericarp water loss, delay the pericarp browning, and also cause the reduction of the pericarp PPO activity and LcPPO expression level within 3 d postharvest. In addition, postharvest storage of Feizixiao fruit stored at 4°C delayed the pericarp browning while decreasing the pericarp PPO activity and LcPPO expression level within 2 d after harvest. Thus, we concluded that the up-regulation of LcPPO expression in pericarp at early stage of postharvest storage likely enhanced the PPO activity and further accelerated the postharvest pericarp browning of litchi fruit.     

香蕉芒果果皮中酶活性与炭疽病菌潜伏侵染的关系

在树上正生长发育的香蕉果实,随着果实长大,果皮中过氧化物酶(POD)和多酚氧化酶(PPO)活性不断升高。采后的香蕉和芒果果实的果皮中,POD和PPO活性变化与呼吸代谢相关。苯丙氨酸解氨酶(PAL)主要分布在果皮中,并随着果实成熟度的提高,其活性呈极显著下降趋势。感病果实的果皮中三种酶活性均比健康果皮高。说明果皮中三种酶活性的变化与炭疽菌的潜伏侵染有关。