Wu Bi-cheng, Degner Brian, McClements David Julian
Department of Food Science, University of Massachusetts, Amherst, MA 01003.
J Phys Condens Matter. 2014 Nov 19;26(46):464104. doi: 10.1088/0953-8984/26/46/464104. Epub 2014 Oct 27.
Soft matter physics principles can be used to address important problems in the food industry. Starch granules are widely used in foods to create desirable textural attributes, but high levels of digestible starch may pose a risk of diabetes. Consequently, there is a need to find healthier replacements for starch granules. The objective of this research was to create hydrogel particles from protein and dietary fiber with similar dimensions and functional attributes as starch granules. Hydrogel particles were formed by mixing gelatin (0.5 wt%) with pectin (0 to 0.2 wt%) at pH values above the isoelectric point of the gelatin (pH 9, 30 °C). When the pH was adjusted to pH 5, the biopolymer mixture spontaneously formed micron-sized particles due to electrostatic attraction of cationic gelatin with anionic pectin through complex coacervation. Differential interference contrast (DIC) microscopy showed that the hydrogel particles were translucent and spheroid, and that their dimensions were determined by pectin concentration. At 0.01 wt% pectin, hydrogel particles with similar dimensions to swollen starch granules (D3,2 ≈ 23 µm) were formed. The resulting hydrogel suspensions had similar appearances to starch pastes and could be made to have similar textural attributes (yield stress and shear viscosity) by adjusting the effective hydrogel particle concentration. These hydrogel particles may therefore be used to improve the texture of reduced-calorie foods and thereby help tackle obesity and diabetes.
软物质物理原理可用于解决食品工业中的重要问题。淀粉颗粒在食品中被广泛使用以产生理想的质地属性，但高含量的可消化淀粉可能带来糖尿病风险。因此，需要找到更健康的淀粉颗粒替代品。本研究的目的是用蛋白质和膳食纤维制备尺寸和功能属性与淀粉颗粒相似的水凝胶颗粒。通过在高于明胶等电点（pH 9，30°C）的pH值下将明胶（0.5 wt%）与果胶（0至0.2 wt%）混合来形成水凝胶颗粒。当pH值调至pH 5时，由于阳离子明胶与阴离子果胶通过复合凝聚产生静电吸引，生物聚合物混合物自发形成微米级颗粒。微分干涉对比（DIC）显微镜显示水凝胶颗粒是半透明的球体，其尺寸由果胶浓度决定。在果胶含量为0.01 wt%时，形成了尺寸与膨胀淀粉颗粒相似（D3,2≈23 µm）的水凝胶颗粒。所得水凝胶悬浮液的外观与淀粉糊相似，并且通过调节有效水凝胶颗粒浓度可使其具有相似的质地属性（屈服应力和剪切粘度）。因此，这些水凝胶颗粒可用于改善低热量食品的质地，从而有助于应对肥胖和糖尿病问题。
