Food Process Engineering, Wageningen University, Wageningen, The Netherlands.
Food Res Int. 2018 May;107:281-288. doi: 10.1016/j.foodres.2018.02.037. Epub 2018 Feb 16.
Concentrated soy protein isolate (SPI) - pectin blends acquire fibrous textures by shear-induced structuring while heating. The objective of this study was to determine the viscoelastic properties of concentrated SPI-pectin blends under similar conditions as during shear-induced structuring, and after cooling. A closed cavity rheometer was used to measure these properties under these conditions. At 140 °C, SPI and pectin had both a lower G* than the blend of the two and also showed a different behavior in time. Hence, the viscoelastic properties of the blend are richer than those of a simple composite material with stable physical phase properties. In addition, the G' was much lower compared with the G' and G' upon cooling, confirming that pectin formed a weak dispersed phase. The results can be explained by considering that the viscoelastic properties of the blend are influenced by thermal degradation of the pectin phase. This degradation leads to: i) release of galacturonic acid, ii) lowering of the pH, and iii) water redistribution from the SPI towards the pectin phase. The relative importance of those effects are evaluated.
浓缩大豆蛋白分离物（SPI）-果胶混合物在加热的同时通过剪切诱导结构获得纤维质地。本研究的目的是确定浓缩 SPI-果胶混合物在类似于剪切诱导结构过程中的条件下以及冷却后的粘弹性特性。使用封闭腔流变仪在这些条件下测量这些性质。在 140°C 时，SPI 和果胶的 G*均低于两者的混合物，并且在时间上也表现出不同的行为。因此，混合物的粘弹性性质比具有稳定物理相性质的简单复合材料更为丰富。此外，与冷却后的 G'相比，G'要低得多，这证实了果胶形成了较弱的分散相。可以通过考虑混合物的粘弹性性质受果胶相热降解的影响来解释这些结果。这种降解导致：i）半乳糖醛酸的释放，ii）pH 值降低，以及 iii）水从 SPI 向果胶相的重新分配。评估这些影响的相对重要性。
