Abstract In this work, the binding of polyphenols isolated from coffee (PIC) with milk protein fractions was investigated by using different spectroscopic techniques as Fourier Transform Infrared Spectroscopic technique, high-performance liquid chromatography, and fluorescence quenching emission method. The polyphenols fraction was isolated from coffee powder using a chromatographic column packed with lipophilic Sephadex LH-20 gel, while there are different types of milk proteins skim milk 3% protein (SM), acid casein (β-Casein (β-CN), α-Casein (α-CN), κ-Casein (κ-CN)), and whey protein isolate (WPI) (β-lactoglubulin (β-Lg) and α-lactalbumin (α-La)) were investigated. From our study, the optimum pH for precipitating complex from the interaction of polyphenols with milk proteins, WPI, acid casein was 5, 8, and 7, respectively. Also, the fluorescence quenching method for polyphenols-proteins interaction exhibited fluorescence quenching in the descending order of α-CN > β-Lg > SM3% > WPI > α-La > acid casein > β-CN > κ-CN for milk proteins. Furthermore, vibrational absorption mode of the functional groups confirmed of the appearing the polyphenols-proteins interaction. Besides, the percentage of interaction between milk protein fractions with PIC was mentioned using HPLC technique.

中文翻译：

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咖啡分离多酚与牛奶蛋白相互作用的光谱研究

摘要 在这项工作中，通过使用傅立叶变换红外光谱技术、高效液相色谱和荧光猝灭发射法等不同光谱技术研究了从咖啡中分离出的多酚 (PIC) 与乳蛋白组分的结合。使用填充亲脂性 Sephadex LH-20 凝胶的色谱柱从咖啡粉中分离多酚组分，而有不同类型的牛奶蛋白脱脂牛奶 3% 蛋白 (SM)、酸性酪蛋白 (β-酪蛋白 (β-CN)、研究了α-酪蛋白（α-CN）、κ-酪蛋白（κ-CN））和乳清蛋白分离物（WPI）（β-乳球蛋白（β-Lg）和α-乳清蛋白（α-La））。根据我们的研究，从多酚与牛奶蛋白、WPI、酸性酪蛋白的相互作用中沉淀复合物的最佳 pH 值分别为 5、8 和 7。还，多酚-蛋白质相互作用的荧光猝灭方法对牛奶蛋白质的荧光猝灭顺序为α-CN>β-Lg>SM3%>WPI>α-La>酸性酪蛋白>β-CN>κ-CN。此外，官能团的振动吸收模式证实了多酚-蛋白质相互作用的出现。此外，使用 HPLC 技术提到了乳蛋白级分与 PIC 之间相互作用的百分比。