系统考察了不同比例的玉米淀粉/酪蛋白的凝胶质构特性,并利用差示扫描量热和激光拉曼光谱技术对玉米淀粉与酪蛋白复合物的热力学性质和分子结构的变化进行了研究。结果袁明,玉米淀粉循釜蛋白凝肢的硬度、黏附性、胶黏性、咀嚼性与玉米淀粉和酪蛋白之间的比例密切相关,在酪蛋白含量占固形物比例为40.0%-50%时其凝胶质构性能发生较大变化。由差示扫描量热分析可知,当酪蛋白含量由40.0%增至45.5%时,玉米淀粉与酪蛋白共混体系凝胶相转变峰向高温移动,峰形变窄,焓值变小,说明该复合凝胶体系中存在一定量的有序化结构,其整体热力学性能稳定且均一性更好。经激光拉曼光谱分析,淀粉分子与酪蛋白分子之间由于相互作用不同其微观结构不同,当酪蛋白含量为40.0%时淀粉特征峰消失,CH2弯曲振动信号大幅增强,C-H伸缩振动峰偏移,酰胺Ⅰ和酰胺Ⅲ均观察到明显的α螺旋和β转角结构,二硫键形成的扭曲啦曲坂式构象(g-g-t)发生较大变化,此时玉米淀粉与酪蛋白形成了复合凝胶体系。
In the present study, the textural properties of corn starch/casein complex were investigated. Differential Scanning Calorimetry and Raman Spectroscopy were applied to study the thermodynamics and structure properties of the complex. Results showed that texture profile parameters including hardness, adhesiveness, gumminess and chewiness were greatly affected by the constitution of the complex. When casein constituted 40% -50% of the total amount, the performance of the complex changed a lot. DSC tests revealed that as the content of casein went up from 40% to 45.5%, corn starch/casein mixed gels saw a narrower phase transition peak at higher temperature and the entropy decreased, indicating the existence of certain amount of ordered structure in the complex and more stable and homogeneous thermodynamic property of the system. Raman Spectroscopy analysis stated that the interaction between starch and casein affected the micro-structure of the complex. When casein constituted 40% of the total amount, characteristic Raman Spectral lines belonging to starch were unclear, the signal of CH2 bending vibration increased greatly and the C-H stretching vibration shifted. Alpha helix and beta turn secondary structure of Amide I and Amide III bands belonging to casein were obviously observed and disulfide bonds in gauche-gauche-wans mode changed a lot, demonstrating the formation of corn starch/casein compound gels.