豆腐凝胶形成过程中蛋白质变化研究.pdfVIP

12 0 2009, Vol. 30, No. 19 食品科学 ※基础研究 豆腐凝胶形成过程中蛋白质变化研究 1,2 2 1, 杨 芳 ，潘思轶 ，张丛兰 * (1.湖北大学知行学院，湖北武汉 4300 11；2.华中农业大学食品科学技术学院，湖北 武汉 430070) 摘 要：研究豆腐凝胶形成过程中蛋白质和水分状态的变化。结果表明：大豆磨浆后加热前，溶液中蛋白质的 α- 螺旋、β- 折叠以及β- 转角含量均为0 ，蛋白质几乎完全以无规卷曲形式存在。煮沸后冷却到80 ℃，点浆后充 分搅拌，α- 螺旋含量增大。点浆后20min ，α- 螺旋和β- 转角略有增大，β- 折叠明显减少，无规卷曲明显增多。 点浆后50min ，稳定的凝胶网络基本形成。压榨后形成的豆腐，α- 螺旋含量减少，β- 折叠含量升高。同时，凝 胶网络中的平衡水含量下降，可冻结水含量下降，非冻结水含量先降低后升高。 关键词：豆腐；凝胶；蛋白质；水分状态；结构 Structural Change of Protein during Tofu Gelation Process 1,2 2 1, YANG Fang ，PAN Si-yi ，ZHAN G Cong-lan * (1. Zhixing College of HuBei University, Wuhan 4300 11, China ； 2. College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China) Abstract ：The changes in protein structure and water state were studied during tofu gelation process. Results indicated that α-helix, β-sheet and β-turn in soybean protein were not observed before heating treatment of soybean milk and coil was the dominant secondary structure of soybean protein. However, when boiled soybean milk was cooled to 80 ℃and plaster was added in it, higher level of α-helix was observed. Twenty minutes later, the percentages of α-helix and β-turn structures exhibited a slight increase while the percentage of β- sheet exhibited an obvious decrease; in contrast, the coil structure revealed a significant increase. Fifty minutes later, a stable gel net was formed. Pressed tofu exhibited a declining level of α-helix and an increasing level of β-sheet. Meanwhile, the contents of unfreezable water fir