稻米陈化中谷蛋白变化光谱解析及其对功能性质的影响  

Spectral Analysis of Glutelin Changes During Rice Aging and Its Effects on Glutelin Functional Properties

作　　者：宁俊帆 郭玉宝[1] 宋睿 朱世民 董鹏 NING Jun-fan;GUO Yu-bao;SONG Rui;ZHU Shi-min;DONG Peng(School of Biological and Food Engineering,Anhui Polytechnic University,Wuhu 241000,China)

机构地区：[1]安徽工程大学生物与食品工程学院,安徽芜湖241000

出　　处：《光谱学与光谱分析》2021年第11期3431-3437,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(31671784)资助。

摘　　要：稻米储藏陈化导致食用品质下降,蛋白质变化是重要诱因。谷蛋白是稻米中主要蛋白,采用拉曼和红外光谱表征陈化中谷蛋白的变化,并对其功能性质差异进行比较,利于阐明稻米的陈化机理。拉曼光谱表明,陈米谷蛋白1 665和1 218 cm-1处的拉曼归一化强度分别为1.01和0.25,明显低于新米谷蛋白,表明陈化后谷蛋白的α-螺旋减少;陈米谷蛋白中二硫键(516和527 cm-1处峰强度分别为0.45和0.42)、亚砜(1 035 cm-1处峰强度为0.48)和砜(1 124, 1 152, 1 159, 1 316和1 334 cm-1处峰强度分别为0.47, 0.22, 0.26, 0.50和0.63)的强度明显高于新米谷蛋白,表明含硫氨基酸残基发生明显氧化;陈米谷蛋白的酪氨酸Fermi共振857/830 cm-1的强度比值1.68明显高于新米谷蛋白,酪氨酸残基更加暴露;陈米谷蛋白751 cm-1附近色氨酸的拉曼强度为0.20,比新米谷蛋白的强度0.14显著提高,陈化后谷蛋白色氨酸残基更加埋藏;陈米谷蛋白3 423 cm-1处的O—H伸缩强度为0.05,比新米谷蛋白对应强度0.02显著增大,表明分子间结合程度升高,谷蛋白与淀粉分子结合更加紧密。除了酪氨酸的Fermi共振、 1 333和1 152 cm-1处砜的吸收峰不高外,陈化谷蛋白的其余拉曼强度均高于陈米谷蛋白,说明陈化谷蛋白的氧化程度更高。红外光谱表明,陈米谷蛋白和陈化谷蛋白中1 153, 1 078和1 026 cm-1处的硫氧化物吸收峰增大,进一步支持谷蛋白发生了氧化。与新米谷蛋白相比,陈米谷蛋白的溶解性、持水性、乳化性和乳化稳定性均显著降低,而持油性升高,支持陈米中谷蛋白发生了明显氧化。陈化谷蛋白的溶解性(除pH 9)、持水性和乳化性比陈米谷蛋白更低,持油性更高,表明新米谷蛋白被提取出来后单独陈化时氧化程度更深。陈化后谷蛋白功能性质的变化支持红外和拉曼光谱显示的氧化变化,这为阐明蛋白质在陈米品质劣变中的作用提供了光谱依据,为控制稻米陈�Rice aging during storage leads to a decline in eating quality, and protein changes are the underlying reasons. Glutelin is the main protein in rice. Raman and infrared spectroscopy were used to characterize the changes in glutelin during aging, and the differences in functional properties were compared, which was helpful to clarify the mechanism of rice aging. Raman spectroscopy showed that the normalized Raman intensities of aged rice glutelin at 1 665 and 1 218 cm-1 were 1.01 and 0.25, significantly lower than fresh rice glutelin, indicating a decreased α-helix in glutelin after rice aging. The disulfide bonds(the peak intensities at 516 and 527 cm-1 were 0.45 and 0.42 respectively), sulfoxides(the peak intensity at 1 035 cm-1 was 0.48) and sulfones(the peak intensities at 1 124, 1 152, 1 159, 1 316 and 1 334 cm-1 were 0.47, 0.22, 0.26, 0.50 and 0.63, respectively) of the aged rice glutelin were significantly higher than those of the fresh rice glutelin, indicating the obvious oxidation of sulfur-containing amino acid residues. The intensity ratio of Fermi resonance at 857/830 cm-1 of tyrosine in aged rice glutelin was 1.68, which was larger than fresh rice glutelin, indicating more exposed tyrosine residues in glutelin after aging. The Raman intensity of the tryptophan indole ring near 751 cm-1 of aged rice glutelin was 0.20, which was significantly higher than the intensity of 0.14 for the tryptophan indole ring of fresh rice glutelin, indicating more buried tryptophan residues after aging. The O—H stretching strength of the aged rice glutelin at 3 423 cm-1 was 0.05, which was significantly higher than that of the fresh rice glutelin of 0.02, indicating that the degree of intermolecular bonding was increased association between glutelin and starch strengthened. Except for the peak intensities of tyrosine Fermi resonance and sulfone at 1 333 and 1 152 cm-1 were not higher, the Raman intensities of fresh rice glutelin-aged at other peaks were higher than those of aged rice glutelin, which indicates that the

关 键 词：稻米 陈化劣变 谷蛋白 红外 拉曼 功能性质 

分 类 号：TS201.2[轻工技术与工程—食品科学]