Yoon Seung-No, Yoo Byoungseung
Department of Food Science and Biotechnology, Dongguk University, Gyeonggi 10326, Korea.
Prev Nutr Food Sci. 2016 Mar;21(1):73-7. doi: 10.3746/pnf.2016.21.1.73. Epub 2016 Mar 31.
Flow and dynamic rheological properties of thickened waters prepared with commercial food thickeners were investigated at different pH levels (3, 4, 5, 6, and 7). The commercial xanthan gum (XG)-based thickener (thickener A) and starch-based thickener (thickener B), which have been commonly used in a domestic hospital and nursing home for patients with swallowing difficulty (dysphagia) in Korea, were selected in this study. Thickened samples with both thickeners at different pH levels showed high shear-thinning flow behaviors (n=0.08~0.22). Thickened samples at pH 3 showed higher n values and lower consistency index (K) values when compared to those at other pH levels. The K values of thickener A increased with an increase in pH level, while the n values decreased, showing that the flow properties greatly depended on pH. There were no noticeable changes in the K values of thickener B between pH 4 and 7. At pH 3, the thickened water with thickener A showed a higher storage modulus (G') value, while that with thickener B showed a lower G'. These rheological parameters exhibited differences in rheological behaviors between XG-based and starch-based thickeners, indicating that the rheological properties of thickened waters appear to be greatly influenced by the acidic condition and the type of food thickener. Appropriately selecting a commercial food thickener seems to be greatly important for the preparation of thickened acidic fluids with desirable rheological properties for safe swallowing.
研究了使用市售食品增稠剂制备的增稠水在不同pH值水平（3、4、5、6和7）下的流动和动态流变特性。本研究选用了韩国国内医院和疗养院中常用于吞咽困难（吞咽障碍）患者的市售基于黄原胶（XG）的增稠剂（增稠剂A）和基于淀粉的增稠剂（增稠剂B）。两种增稠剂在不同pH值水平下的增稠样品均表现出高剪切变稀流动行为（n = 0.08~0.22）。与其他pH值水平相比，pH值为3时的增稠样品显示出更高的n值和更低的稠度指数（K）值。增稠剂A的K值随pH值水平的升高而增加，而n值降低，表明流动特性在很大程度上取决于pH值。增稠剂B在pH值4至7之间的K值没有明显变化。在pH值为3时，使用增稠剂A的增稠水显示出更高的储能模量（G'）值，而使用增稠剂B的增稠水显示出更低的G'值。这些流变参数显示了基于XG的增稠剂和基于淀粉的增稠剂在流变行为上的差异，表明增稠水的流变特性似乎受到酸性条件和食品增稠剂类型的极大影响。对于制备具有理想流变特性以实现安全吞咽的增稠酸性液体而言，适当选择市售食品增稠剂似乎非常重要。
