海藻酸钠-酪蛋白复合乳液凝胶的制备与结构特性表征

Preparation and structural property characterization of sodium alginate-casein composite emulsion gel

以海藻酸钠和酪蛋白为试材制备了海藻酸钠-酪蛋白复合乳液凝胶,采用流变学和电子显微技术探究了不同制备方法及海藻酸钠质量浓度对复合乳液凝胶结构的影响,并讨论了其形成机制。结果表明:当酪蛋白质量浓度固定为80 g/L时,随着海藻酸钠浓度的增加,不含油滴的复合凝胶逐渐由酪蛋白主导的单一网络结构转变为“水包水”乳液结构,此时酪蛋白为连续相,海藻酸钠为分散相;当海藻酸钠质量浓度继续增加至7.5 g/L时,出现双连续相结构。添加油滴后,复合乳液凝胶仍呈现相同的相转变趋势,且2种方法制备的乳液凝胶中,乳滴总是存在于酪蛋白一相中。经比较,2种制备方法对乳液凝胶结构特性的影响有限,但方法一较为简单,其制备的乳液凝胶乳滴粒径较小,且在海藻酸钠质量浓度为4 g/L时形成的复合乳液凝胶质地较好。本研究结果为开发新型凝胶类食品提供了理论依据和技术参考。

Sodium alginate and casein were used to prepare composite emulsion gels,and the effects of different preparation methods and sodium alginate concentrations on the structure of emulsion gels were studied using rheology and electron microscopy.The formation mechanism of sodium alginate-casein composite emulsion gel was discussed.The results showed that,at the casein concentration of 80 g/L,the gel structure gradually transformed from casein-dominated single network to"water in water"emulsion structure with the increasing of alginate concentration.Casein was acted as the continuous phase and sodium alginate was acted as the dispersed phase in the above system.When the concentration of sodium alginate increased to 7.5 g/L,bicontinuous structure was observed.After incorporating oil droplets,the composite emulsion gels still exhibited similar structural transformation,and the oil droplets always located in the casein-dominated phase despite of the preparation difference of the emulsion gels.By comparison,the effects of the two preparation methods on the structural characteristics of emulsion gels were limited,but method 1 was simpler,and the emulsion gel prepared by it showed a smaller particle size.The formed composite emulsion gels displayed better texture when the concentration of sodium alginate was at 4 g/L.Our results provide theoretical basis and technical reference for the development of new gel foods.