【作者】 王蓉蓉；

【导师】 胡小松； 张燕；

【作者基本信息】 中国农业大学 ， 农产品加工及贮藏工程， 2014， 博士

【摘要】 高静压(HHP)技术作为一种新型的食品非热加工技术,大量研究已证实其能较好的保持食品的颜色品质。基于正常植物体中大部分叶绿素存在于色素蛋白复合体中,结合前期实验结果,即HHP处理后的菠菜浆在光照贮藏条件时的颜色品质要好于暗贮藏,我们推测HHP处理后的样品可能仍然保持光反应活性,而类囊体膜是光反应发生的主要部位,其功能的实现是通过其上色素蛋白复合体来维持。因此,植物体光反应相关生理功能的研究对于分析HHP处理后绿色蔬菜叶绿素代谢具有重要的意义。本论文以菠菜为研究对象,选取类囊体膜和PSⅡ颗粒进行研究,从植物生理角度探讨HHP保持绿色蔬菜颜色品质的可能机制,主要结论如下：(1)HHP处理较热处理能很好的保持菠菜叶片贮藏期间的叶绿素荧光动力学参数,具有较高的Fo, Fm和Fv/Fm,证实了HHP处理后菠菜叶片较高的PSⅡ原初光能转化效率和电子传递活性。较高的光反应活性反映了膜上色素蛋白复合体功能的保持,对于其上叶绿素的稳定具有积极的影响。(2)HHP处理对于菠菜体系和类囊体膜溶液体系的影响基本一致。同热处理相比,HHP处理都能较好的保持类囊体膜的垛叠结构及功能。在此基础上进一步以类囊体膜溶液为研究对象,分析贮藏期间HHP保持类囊体膜结构及功能的可能机制,发现类囊体膜多肽组分PSⅠ反应中心的蛋白亚基PsaA/B、PSII中的CP47和CP43组分受高压的影响较小,在压力处理后仍具有稳定性,保持PSⅠ和PSⅡ功能特性。(3)贮藏期间,类囊体膜不饱和脂肪酸指数在HHP(100MPa和250MPa)处理后至整个贮藏期间都呈现逐渐升高的趋势,不饱和脂肪酸指数的升高可以提高植物类囊体膜的流动性和稳定性,对膜蛋白功能的保持具有积极的影响。然而随着压力逐渐增加,500MPaHHP处理组随着贮藏时间的延长,其不饱和脂肪酸指数逐渐降低,这可能与膜脂不饱和化酶的活性在高压适应过程中的抑制有关,从而阻止了原有脂肪酸的脱饱和,此现象仍有待于进一步研究。(4)PSⅡ作为类囊体膜逆境下受影响的起始部位,HHP处理后仍能保持其颗粒结构及捕光活性,且捕获的光能可以进一步被激发传递到PSⅡ反应中心。类囊体膜蛋白多肽CP47、D1、D2、29KD、CP26各组分含量在HHP处理后的降解效果要低于热处理。上述各组分含量的保持能维持PSⅡ复合体中的放氧过程及其在高压下的稳定性,保护整个光合作用体系的活性。因此,HHP处理较热处理能较好的保持PSⅡ颗粒的结构及功能,维持类囊体膜及相关色素蛋白复合体的功能性和稳定性,抑制其中叶绿素的降解。更多还原

【Abstract】 High hydrostatic pressure (HHP) is a novel non-thermal food processing technology due to its limited effects on food color qulity. Based on plant chlorophylls are presented in chlorophyll-protein complexes, combined with our previous research that HHP could better retain green color of spinach puree during storage, and the positive effect induced by HHP in the200lux storage was more significant than that of storage in the dark. It is speculated that physiology activities related to chlorophyll-protein complexes are still existed. The possible physiology mechanism of green color retention in HHP-treated spinach was discussed. The main results were as follows:(1) HHP treatments better retained chlorophyll fluorescence kinetics of spinach leaves during storage compared to thermal treatment, and higher Fo, Fm and Fv/Fm could be found in HHP-treated samples. The results showed that PS II primary light energy conversion efficiency and electron transfer activity were kept, they will better contribute to protection of photosynthetic apparatus. The retention of chlorophyll-protein complexes function could be reflected by higher light reaction activity, it will play a positive role for chlorophyll retention in HHP processing green color vegetables.(2) HHP treated samples showed similar trend for spinach system and thylakoid membrane solution system. HHP treatment could better retain thylakoid membrane stacked structure and harvesting light capacity, further transfer light energy to reaction center, and the positive influence could be continued to storage. HHP treatment had less effect on PsaA/B, CP47and CP43, and they had higher stability after HHP treatments. The functions of PS I and PS Ⅱ could be better kept.(3) For thylakoid membrane fatty acid composition, IUFA of samples after lower pressure (100and250MPa HHP) treatments had similar change with the control, and IUFA increased with storage time. The increase of IUFA presented better fluidity and stability of thylakoid membrane wasretained after lower pressure treatments. It played a protective role for thylakoid membrane chlorophyll-protein complexes and inhibited chlorophyll degradation. However,500MPa HHP-treated samples, IUFA decreased during storage. It might be caused by inhibition of membrane lipid unsaturated enzyme activity under HHP treatment, and desaturation of fatty acid was further inhibited.(4) As thylakoid membrane initiation site affected by stress, PSⅡparticle structure and harvesting light capacity could better retain after HHP treatment, and harvested light energy further was excited and transferred to PS II reaction center. Changes of PS Ⅱ particle polypetides showed that both of HHP and thermal treatments caused degradation of CP47, D1, D2,29KD and CP26to some degree. However, degradation induced by thermal treatment was more serious than that of HHP treatments. Degradations of the above polypetides compoments in HHP-treated samples could better keep oxygen activity of PS Ⅱ particle and the whold photosynthesis system activity. Hence, PS Ⅱ structure and function were maintained after HHP treatment, and higher LHC Ⅱ stability had positive effect on inhibition of chlorophyll degradation.更多还原