Effect of processing conditions on microstructures and properties of hydroxypropyl methylcellulose/hydroxypropyl starch blends. (September 2017)

• Record Type: Journal Article
• Authors: Zhang, Liang; Yu, Long; Liu, Hongsheng; Wang, Yanfei; Simon, George P.; Ji, Zhili; Qian, Jianya
• Is Part Of: Food hydrocolloids. Volume 70(2017)
• Page Start: 251
• Page End: 259
• Publication Date: 2017-09
• Subjects: HPMC -- HPS -- Blending gel -- Microstructure -- Morphology -- Mechanical property; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2017.03.019
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Since hydroxypropyl methylcellulose (HPMC) is a thermal gel while hydroxypropyl starch (HPS) is a cool gel, their blends show some unique and interesting behaviors of phase transitions and microstructures, which control their performances. This work focused on the effect of processing conditions on the microstructure and mechanical properties of these blends with various ratios of HPMC/HPS, in particular for incubation and drying conditions. To clearly identify the changes of starch phase in such blending system, the technique of dyeing HPS with iodine was developed and used. Rheometer, small angel X-ray scattering (SAXS), X-ray diffraction (XRD), dynamic mechanical analysis (DMA) and mechanical testing apparatus were used to study the changes of microstructure and the relative properties of the blending gels and dried films incubated at different temperatures. It was found that the higher incubation temperature resulted in higher storage modulus, more solid-like behavior and more compact self-similar structure of the blending gel. Moreover, the films prepared from the gels dried at high temperature showed higher crystalline degree and more compact amorphous structure, and therefore result in increasing tensile strength and modulus but decreasing elongation. Graphical abstract: Highlights: How thermal and cool blending gel depends on processing condition is explored. Technical to identify starch phase by dyeing with iodine was developed and used. High incubation temperature results high modulus since more self-similar structure. High dry temperature results stronger tensile properties since high crystallinity.