基于高静压加工南瓜黄色品质变化的分子机理研究

The yellow fruits and vegetables are abundant in antioxidant carotenoid pigment. Color can be a significant standard for predicting quality stability of fruit and vegetable processing. High hydrostatic pressure (HHP) is a novel non-thermal food processing technology, which has limited effects on food green color quality has been confirmed by a large number of studies. But the present study has not been involved the influence of high static pressure on yellow color fruit and vegetable quality. However, there is a significant decrease on HHP treated pumpkin color quality in our recent research. This project aims to reveal the change of molecules mechanism of the pigment after high hydrostatic pressure processing. Pumpkin was chosen as the high hydrostatic pressure processing object. The polyene chain of C = C double bond of β-carotene in phase stretching vibration (v1) change and intermolecular interactions, and 0-0 with the peak position and width changes caused by high hydrostatic pressure using the visible-near infrared spectroscopy (VIS/NIR), laser confocal scanning microscope (CLSM) and the Fourier Raman spectra (FT-Raman) technology respectively will be observed firstly. The prediction model of content of β-carotene will be established according to characteristic frequency shift and interception of spectrum. The mechanism of high static pressure the effect of color will be explained from the level of pigment molecules structure. In order to further understand the effects of HHP processing on pumpkin color, the structure of thylakoid membrane, PSⅡparticle composition and the change of the structure and function of the pigment protein complexes will be analyzed from the pigment cell localization. The mechanism of effect of high hydrostatic pressure on pumpkin pigment will be revealed from cellular level furtherly.

黄色果蔬富含抗氧化剂色素类胡萝卜素，色泽被认为是判断果蔬加工后品质稳定性的一项重要指标，高静压(HHP)加工已被证实能较好地保持食品的绿色品质。但经申请人前期研究发现高静压加工南瓜后黄色品质显著下降。本项目旨在揭示南瓜色素分子经高静压处理后的变化机理。首先拟采用可见-近红外光谱（VIS/NIR）、激光共聚焦扫描显微镜（CLSM）和傅里叶拉曼光谱（FT-Raman）技术分别对高静压处理南瓜的β-胡萝卜素含量计算、检测C=C双键的同相伸缩振动（v1）改变及分子间相互作用，0-0带的峰位和宽度随压力的变化关系，建立特征频移、截取光谱与β-胡萝卜素含量的函数关系预测模型，从色素分子结构水平揭示高静压对色泽的影响机理。为了进一步了解HHP加工对南瓜色泽的影响，进而从色素细胞定位角度深入研究，分析类囊体膜、PSⅡ颗粒组分及蛋白色素复合体的结构及功能的变化，从细胞水平揭示高静压对南瓜色素影响的变化机理。

南瓜作为黄色果蔬的研究对象，富含抗氧化剂色素类胡萝卜素，探讨了高静压对南瓜色泽品质、杀菌效果及理化指标的影响，同时协同超声波非热加工技术探索了对典型黄色果蔬中国南瓜色泽及营养品质进行了研究，系统研究了高静压处理对三个南瓜品种类胡萝卜素含量（β-胡萝卜素，α-胡萝卜素，β-隐黄素，玉米黄质，番茄红素）、颜色参数(L*、a*、b*、C*、h0、ΔE、褐变指数(BI)、黄变指数(YI)、影响色泽的多酚氧化酶（PPO）和过氧化物酶（POD）酶活、类囊体膜蛋白含量；pH、硬度、Vc、可溶性糖、总酚、抗氧化性、风味品质等理化指标的影响。研究表明，高静压处理可将三个南瓜品种中的细菌、霉菌和酵母失活，达到商业无菌，并最大程度的保留营养品质，符合非线性数学模型拟合的微生物失活动力学。高静压协同超声处理未引起南瓜色泽显著变化(p>0.05)，类胡萝卜素含量和云值显著升高(P<0.05)；酶活性，粒径分布，流变学特性（剪切应力，表观粘度，储能模量，损耗模量）显著下降（P<0.05）；微结构发生明显变化，细胞结构不完整。随着贮藏时间增加，南瓜类胡萝卜素含量，云值，粒径分布，多分散性的变化不明显；类囊体膜可溶性蛋白含量呈现先升高，后降低的趋势，阐明可溶性蛋白参与类囊体膜的构建、色素蛋白复合物的组成、类囊体膜结构和理化特性的保持以及色素的稳定，从细胞水平揭示了高静压对南瓜色素影响的变化机理，研究结果可为高静压协同超声波技术在果蔬保鲜加工领域提供理论支持。