Effects of Salts on the Thermal Reversibility of Starch and Hsian-tsao (Mesona procumbens Hemsl) Leaf Gum Mixed System

Effect of hyperbranched poly(trimellitic glyceride) paired with different metal ions on the physicochemical properties of starch

The novel hyperbranched poly(trimellitic glyceride) (PTG) starch plasticizer synthesized in our previous study was neutralized with different alkaline metal hydroxides. Mixed with starch, the effects of different alkaline metal cations, M⁺, on gelatinization of starch suspensions and thermal behaviors of the films were analyzed using RVA and DMA, respectively. The structures of the starch suspensions, films and freeze-dried samples (S/PTG-M) were investigated using DSC, XRD and FTIR spectroscopy, respectively. M⁺ increased the gelatinization temperature of starch suspensions in the order of S/PTG-Li > S/PTG-Na > S/PTG-K. The formation of a complex between M⁺ and starch in the films observed using FTIR spectroscopy improved the stability of the starch paste and gel, and increased the gel temperature of starch dispersions. The corresponding starch gel was relatively thermostable, but not shear-resistant. PTG decreased the T_g of starch films with different paired M⁺. PTG-Li and PTG-K, but not PTG-Na, strengthened the mechanical properties of starch films.

Effect of Magnesium and Iron on the Hydration and Hydrolysis of Guar Gum

The effect that magnesium and iron have on the hydration and hydrolysis of guar gum at pH 12 was studied as a function of viscosity. It was found that small concentrations of magnesium do not affect the dissolution ratio of guar but significantly decrease hydrolysis at high temperatures. These results suggest that Mg(OH)(2) forms an adduct with the polysaccharide that prevents thermal hydrolysis of the guar. Viscosity measurements recorded in the presence of iron at pH 12 show that ferric iron inhibits hydration or dissolution of guar and may accelerate chain scission of fully hydrated guar when solutions are heated in an autoclave at 121 degrees C.