Guan Yufang, Ye Fayin, Liu Jia, Zhao Guohua
College of Food Science, Southwest University , Chongqing 400715, PR China.
J Agric Food Chem. 2013 Nov 27;61(47):11653-9. doi: 10.1021/jf404029h. Epub 2013 Nov 15.
The interaction between ε-polylysine (ε-PL) and anionic polysaccharides has gained considerable attention recently because of its scientific impact on the stability and appearance of liquid food systems. The purpose of this study was to characterize the interactions between ε-PL and carboxymethyl sweet potato starch (CSS) using isothermal titration calorimetry (ITC), electrical charge, and turbidity measurements. The results showed that the interaction between ε-PL and CSS was electrostatic and mainly dependent on the molar ratio of amino groups in ε-PL to carboxyl groups in CSS. Additionally, the interaction between ε-PL and CSS was also associated with pH, degree of substitution (DS) of CSS, and ionic strength of the system. For the interaction of ε-PL with high DS (>0.235) CSS, three states of the ε-PL/CSS mixture were observed as transparent, turbid, and precipitated with a successive increase in amino/carboxyl molar ratio. Distinguishingly, a transparent mixture could be obtained for CSS with low DS (0.114) at a sufficiently high amino/carboxyl molar ratio. The present study provided basic guidance in designing liquid food systems containing both ε-PL and CSS.
由于ε-聚赖氨酸（ε-PL）与阴离子多糖之间的相互作用对液态食品体系的稳定性和外观具有科学影响，近年来受到了广泛关注。本研究的目的是使用等温滴定量热法（ITC）、电荷和浊度测量来表征ε-PL与羧甲基红薯淀粉（CSS）之间的相互作用。结果表明，ε-PL与CSS之间的相互作用是静电作用，主要取决于ε-PL中氨基与CSS中羧基的摩尔比。此外，ε-PL与CSS之间的相互作用还与pH值、CSS的取代度（DS）以及体系的离子强度有关。对于ε-PL与高取代度（>0.235）CSS的相互作用，随着氨基/羧基摩尔比的连续增加，观察到ε-PL/CSS混合物有三种状态，即透明、浑浊和沉淀。值得注意的是，在足够高的氨基/羧基摩尔比下，低取代度（DS为0.114）的CSS可以得到透明混合物。本研究为设计同时含有ε-PL和CSS的液态食品体系提供了基本指导。
