应用低场核磁共振(low-field nuclear magnetic resonance, LF-NMR)与傅里叶红外光谱技术(Fourier transform infrared spectroscopy, FT-IR),研究斩拌阶段不同盐处理(空白组、食盐组、磷酸盐组、食盐+磷酸盐组)对肉糜乳化凝胶水合特性及蛋白质构象变化的影响。结果表明,与空白组相比,食盐组与食盐+磷酸盐组T2增加,3个加盐处理组均表现出P2b和P22降低,而P21升高;相关性分析显示,β-折叠含量与乳化凝胶T21、T22呈显著负相关(R=-0.970,p＜0.05;R=-0.960,p＜0.05);α-螺旋含量与乳化凝胶P2b呈显著负相关(R=-0.971,p＜0.05),与P21呈显著正相关(R=0.980,p＜0.05);食盐单独加入使得部分无规则卷曲向α-螺旋转变,磷酸盐单独添加使得部分无规则卷曲向β-折叠转变。说明添加盐类斩拌之后,水分的整体流动性增加,肉糜中不易流动水的含量升高,自由水含量降低。相关性结果表明,水分整体流动性增加以及不易流动水含量升高后,乳化凝胶β-折叠含量下降,主要是因为食盐的加入造成无规则卷曲向α-螺旋转变。因此,斩拌阶段的盐处理方式不同,肉糜凝胶的水合特性不同。肉糜水合特性出现差异,从而造成肉糜凝胶蛋白质构象差异化,进而可能影响凝胶品质。
Low-field nuclear magnetic resonance (LF-NMR) and Fourier transform infrared spectroscopy (FT-IR) technique were used to study the influence of salt treatments on protein hydration properties and molecular conformation of emulsified gel. Meat batters were prepared by different ways such as only NaCl, only polyphosphates and NaCl and polyphosphates, the control group had no salt. Results indicated that compared with the control group, relaxation time T2 of the salt group and the salt+polyphosphates group were increased. While peak area proportion P2b and P22 decreased and P21 increased among the three treatment groups (except the control group). The correlation analysis showed that the β-sheets content was negatively correlated (R=-0.970, p＜0.05; R=-0.960, p＜0.05) with relaxation time T21 and T22 of the emulsified gel, and the α-helix content was negatively correlated (R=-0.971, p＜0.05) with the peak area proportion P2b and was positively correlated (R=0.980, p＜0.05) with P21. The NaCl addition made some irregular curl transformed to α-helix, while the phosphate transformed irregular curl to β-sheets. The result suggested that chopping with salt, the total mobility of water was increased, the content of immobilized water increased accompanied with the decrease of free water. With the increasing of total mobility of water and content of free water, the β-sheets content of emulsified gel was decreased. This was mainly caused by salt which made some irregular curl transformed to α-helix. Therefore, different salt treatment affected hydration property of meat emulsion, and caused gel properties difference and protein conformation change which affected the gel quality.
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