牛奶热处理和酸性pH可增加均质脂肪球对蛋白质的粘附力：AFM力谱提供的定量见解。,Food Research International

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牛奶热处理和酸性pH可增加均质脂肪球对蛋白质的粘附力：AFM力谱提供的定量见解。
Food Research International ( IF 7.0 ) Pub Date : 2019-12-03 , DOI: 10.1016/j.foodres.2019.108847
Sameh Obeid ₁ , Fanny Guyomarc'h ₁ , Gaëlle Tanguy ₁ , Nadine Leconte ₁ , Florence Rousseau ₁ , Anne Dolivet ₁ , Arlette Leduc ₁ , Xiaoxi Wu ₁ , Chantal Cauty ₁ , Gwénaël Jan ₁ , Frédéric Gaucheron ₂ , Christelle Lopez ₃

Affiliation

乳胶的流变性质和微观结构涉及乳脂小球（MFG）和酪蛋白胶束之间的连接性，该连接性受诸如牛奶均质化和热处理等技术过程的影响。潜在的机理要求在纳米级水平上进一步定量相互作用，以便完全理解和控制。在这项研究中，我们检查了均质的MFG对牛奶蛋白的粘附力，并评估了超高温（UHT）热处理和pH的作用。使用了与原子力显微镜（AFM）力谱相关的不同规模的物化分析，流变学和显微镜观察的组合。在粒度水平上进行的AFM实验表明，单个均质的MFG对牛奶蛋白的粘附力（1）在pH 4.5酸化时会增加：未加热的样品为1.4倍，UHT样品为3.5倍，（2）提高了约1.7在牛奶中进行UHT热处理后，pH值从176 pN增至296 pN时，其折叠倍数为7.6，这要归功于MFG和酪蛋白表面的高反应性热变性乳清蛋白。与未加热的牛奶凝胶相比，增加的粒子间粘附力导致更多的连接结构和更硬的UHT牛奶酸凝胶。使用多尺度方法，这项研究表明，牛奶的热处理显着影响了颗粒表面水平上发生的相互作用，从而影响了酸性凝胶的整体结构和流变特性。这些发现对于制造商通过定制热诱导的蛋白质复合物以及均质化的MFG与蛋白质网络的连通性来调节发酵乳制品的质地将是有用的。这项工作还将有助于更好地理解过程引起的变化对蛋白质和脂质的消化率和代谢命运的影响。

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The adhesion of homogenized fat globules to proteins is increased by milk heat treatment and acidic pH: Quantitative insights provided by AFM force spectroscopy.

The rheological properties and microstructure of dairy gels involve the connectivity between milk fat globules (MFG) and casein micelles that is affected by technological processes such as milk homogenization and heat treatment. The underlying mechanisms require further quantification of the interactions at the nanoscale level to be fully understood and controlled. In this study, we examined the adhesion of homogenized MFG to milk proteins and evaluated the role of ultra-high temperature (UHT) heat treatment and pH. The combination of physico-chemical analysis, rheology and microscopy observations at different scale levels associated to atomic force microscopy (AFM) force spectroscopy were used. AFM experiments performed at the particle scale level showed that adhesion of individual homogenized MFG to milk proteins (1) is increased upon acidification at pH 4.5: 1.4 fold for unheated samples and 3.5 fold for UHT samples, and (2) is enhanced by about 1.7 fold at pH 4.5 after UHT heat treatment of milk, from 176 pN to 296 pN, thanks to highly-reactive heat-denatured whey proteins located at the surface of MFG and caseins. The increased inter-particle adhesion forces accounted for more connected structures and stiffer UHT milk acid gels, compared to unheated-milk gels. Using a multiscale approach, this study showed that heat treatment of milk markedly affected the interactions occurring at the particle's surface level with consequences on the bulk structural and rheological properties of acid gels. Such findings will be useful for manufacturers to modulate the texture of fermented dairy products through the tailoring of heat-induced complexation of proteins and the connectivity of homogenized MFG with the protein network. This work will also contribute in a better understanding of the impact of process-induced changes on the digestibility and metabolic fate of proteins and lipids.

更新日期：2019-12-04

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