Rheological, pasting, and structural properties of potato starch by cross-linking

Abstract

ABSTRACTThe present study determined the effects of cross-linking with sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) on the structural, rheaological, and pasting properties of potato starch. Starches cross-linked by STMP/STPP at 0.0125%, 0.025%, 0.05%, 0.5%, 5%, and 10% were designated as the cross-linking of potato starch (CLPS)-0.0125, CLPS-0.025, CLPS-0.05, CLPS-0.5, CLPS-5, and CLPS-10, respectively. Scanning electron microscope revealed that STMP/STPP treatment resulted in some changes in the surface of the native potato starch (NPS) granules. An analysis with a light microscope showed that NPS granules were completely ruptured and had disappeared but that the granules of CLPS-0.0125, CLPS-0.025, and CLPS-0.05 were scarcely ruptured after heating at 95°C for 30 min. The 31P nuclear magnetic resonance spectra of CLPS-5 and CLPS-10 showed new peaks of monostarch diphosphate, cyclic-monostarch monophosphate, and distarch monophosphate. Pastes of CLPS-0.0125, CLPS-0.025, and CLPS-0.05 exhibited significantly higher shear-thinning fluid characteristics than NPS. Steady and dynamic shear analysis showed that, compared to NPS, CLPS pastes (0.5, 5, and 10) had significantly greater apparent viscosity (ηa,100), consistency index (K), yield stress (σoc), dynamic moduli (G′, G″), and complex viscosity (η*). These results indicate that cross-linking with STMP/STPP can be used to improve the rheaological and pasting properties of potato starch for desired food applications.