食品科学

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低场核磁共振法研究NaCl对肌原纤维蛋白凝胶水分分布和移动性的影响

韩敏义,刘永安,王 鹏,邹玉峰,徐幸莲,周光宏   

  1. 1.南京农业大学 农业部畜产品加工重点实验室,食品安全与营养协同创新中心,江苏 南京 210095;
    2.河南省产品质量监督检验院,国家粮油及肉制品质量监督检验中心,河南 郑州 450004
  • 出版日期:2014-11-15 发布日期:2014-11-06

Water-Holding Capacity in Heat-Induced Gelation of Myofibrillar Proteins as Affected by NaCl Concentration: A Low-Field NMR Study

HAN Min-yi, LIU Yong-an, WANG Peng, ZOU Yu-feng, XU Xing-lian, ZHOU Guang-hong   

  1. 1. Key Laboratory of Animal Products Processing, Ministry of Agriculture, Synergetic Innovation Center of Food Safety and Nutrition,
    Nanjing Agricultural University, Nanjing 210095, China; 2. National Grain Oil & Meat-Food Product Supervision and Inspection Center,
    Henan Institute of Product Quality Inspection and Detection, Zhengzhou 450004, China
  • Online:2014-11-15 Published:2014-11-06

摘要:

为解决凝胶类肉制品含盐量过高的问题,探讨了NaCl浓度对猪肉肌原纤维蛋白热诱导凝胶水分分布和移动性的影响。分别用离心法、低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)、扫描电镜研究不同NaCl浓度下的猪肉肌原纤维蛋白凝胶保水性、水分移动性及分布状态和凝胶微观结构,并用主成分分析探讨它们之间的相关性。结果表明:随着NaCl浓度的上升猪肉肌原纤维蛋白的保水性显著增加、加热后形成了多孔致密的结构。LF-NMR T2驰豫反演为4 个峰,其加权T2分别为0.62~3.89、4.62~35.28、59.06~153.22、1 198.75~1 518.17 ms;合并后分别对应水的3 种存在状态,即大分子结合水、不易流动水和自由流动水。加入NaCl使水的移动性下降,并且使不易流动水的峰面积显著增加(P<0.05),从而增加了保水性。主成分分析结果显示不同NaCl浓度凝胶样品在主成分评分图上表现出明显的聚类,低浓度的NaCl在第1主成分的右端,而高浓度在第1主成分的左端,从变量评分图上也可以看出不同指标NaCl浓度的变化情况。因此,不同NaCl浓度下凝胶保水性的改善和不易流动水的增加明显相关。

关键词: 低场核磁共振, 肌原纤维蛋白, 热诱导凝胶, 水分分布, 主成分分析

Abstract:

Objective: To investigate the effect of NaCl concentration on water distribution and mobility of pork myofibrillar
protein (PMP) during heat-induced gelation in order to reduce the salt content of gel-type meat products. Methods: The
water-holding capacity (WHC), T2 relaxation time, and gel microstructure were determined by centrifugation method, lowfield
nuclear magnetic resonance (NMR) and scanning electron microscope (SEM), respectively. Principal component
analysis (PCA) was conducted to find out the main sources of data variability and the relationship between or within
samples and variables. Results: Obvious changes in WHC, T2 relaxation parameters and gel microstructure of PMP gel were
observed with increasing NaCl concentration from 0 to 0.6 mol/L. The addition of NaCl resulted in a significant (P < 0.05)
increase in the WHC of PMP heat-induced gel, which was ascribed to the more fine microstructure with increase of NaCl
concentration. The distributed water proton and NMR T2 relaxation of different contents of NaCl after heat treatment were
characterized by two minor peaks with relaxation time of 0.62–3.89 ms and 4.62–35.28 ms, a major band with relaxation
time of 59.06–153.22 ms. In addition, a wide peak was also observed in the range between 1 198.75 and 1 518.17 ms. These
four populations probably represent three water states, i.e., bound, immobile and bulk water according to previous literature.
The position of the major peak obviously shifted to higher relaxation time with increasing NaCl level, and the peak area
fraction increased, which contributed to the increasing WHC. The addition of NaCl resulted in gels with quite homogenous
microstructure and decreased pore size after heat treatment, which was observed by SEM. The PCA results showed that the
first two principal components (PC) could explain 91.23% of the total variance. The samples obtained with different NaCl
concentrations revealed a tendency to group into three clusters. The low levels of NaCl were located in the left side of the
PCA score plots, characterized low WHC, T23, P22, whereas the high contents of NaCl were positioned in the right side and
characterized the opposite attributes, and the mediate NaCl concentration located in the middle. The correlation of these
parameters was displayed in the PCA loading score plot, which displayed a strong correlation of WHC to area fraction of
the major NMR relaxometry population. In conclusion, the gel functional properties are improved with increased NaCl
concentration, which is ascribed to the increase of immoblized water.

Key words: low-field nuclear magnetic resonance, myofibrillar, heat-induced gelation, water distribution, principal component analysis