State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, PR China.
Biopolymers and Colloids Laboratory, Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA.
Food Res Int. 2019 Sep;123:266-275. doi: 10.1016/j.foodres.2019.05.005. Epub 2019 May 3.
Oil-in-water emulsions were prepared that were stabilized by a polyphenol (tannic acid, TA) and/or a polysaccharide (β-glucan, BG). The influence of TA concentration and solution pH on the physical stability and microstructure of the emulsions was investigated. Emulsions formed using only BG (1%) contained large droplets that were unstable to flocculation and coalescence. The stability of the emulsions (pH 5) could be enhanced by optimizing the ratio of TA-to-BG used to form them, i.e., TA/BG = 0.4 or 0.5. This effect was attributed to a combination of increased steric hindrance and reduced hydrogen bonding of TA to BG. Transmission electron microscopy (TEM) indicated that increasing the level of TA present increased the compactness and thickness of the TA-BG interfacial layers formed around the oil droplets. Furthermore, the stability of the emulsions to droplet flocculation and coalescence depended on the TA/BG ratio and solution pH. The impact of environmental conditions on emulsion stability was also investigated. Emulsions stabilized by TA-BG complexes (TA/BG = 0.5) remained stable from pH 5 to 9 at ambient temperature and at temperatures ≤60 °C at pH 5, but were highly unstable to salt addition at pH 5. Our results may increase the breadth of applications of β-glucan as a functional ingredient in foods.
制备了由多酚（单宁酸，TA）和/或多糖（β-葡聚糖，BG）稳定的水包油乳液。研究了 TA 浓度和溶液 pH 值对乳液物理稳定性和微观结构的影响。仅使用 BG（1%）形成的乳液含有大的液滴，对絮凝和聚结不稳定。通过优化形成乳液的 TA 与 BG 的比例（即 TA/BG=0.4 或 0.5），可以增强乳液的稳定性（pH 5）。这种效果归因于 TA 与 BG 之间的空间位阻增加和氢键减少的组合。透射电子显微镜（TEM）表明，增加存在的 TA 水平会增加围绕油滴形成的 TA-BG 界面层的紧密性和厚度。此外，乳液对液滴絮凝和聚结的稳定性取决于 TA/BG 比和溶液 pH 值。还研究了环境条件对乳液稳定性的影响。在环境温度下，pH 值为 5 至 9 时，由 TA-BG 复合物（TA/BG=0.5）稳定的乳液保持稳定，在 pH 值为 5 时，温度≤60°C 时也保持稳定，但在 pH 值为 5 时，添加盐会使其高度不稳定。我们的结果可能会增加 β-葡聚糖作为食品中功能性成分的应用范围。
