Flow characteristics and gelatinization kinetics of rice starch under strong alkali conditions

Abstract

The normality dependence and the kinetics of flow behavior in the rice starch dispersion under strong alkali conditions were studied. Non-Newtonian flow (power-law) quantities n and µ (σ = µ(˙ ) n ; σ: shear stress,˙ : shear rate) of the samples stored (gelatinized) at 20 • C for 10min after the addition of NaOH solution with the normality 0.090 -0.175N, were measured by a cone-plate type rotational viscometer. For the flow analysis a care was taken for the ambiguity of the analysis range of flow data. The samples added with 0.14 -0.16N NaOH displayed an apparently dilatant flow. As the normality of added NaOH increased, apparent viscosity η a was steeply enhanced in the vicinity of 0.14N and started to grow almost exponentially. Next, the storage time dependence of flow properties was investigated for samples gelatinized for 6 ≤ t[min] ≤ 230 after the addition of 0.146N NaOH solution. A Newtonian analysis of the flow (σ -˙ ) data indicated that viscosity η increased exponentially in the early stage (6 ≤ t ≤ 35) and did linearly in the middle. It was argued that the observed time dependence of viscosity could be described by a first-order reaction hypothesis combined with the fluidity (η −1 ) mixing rule with respect to ungelatinized and gelatinized fractions of starch. The application of this theoretical treatment to the present data suggested that the gelatinization process was composed of plural phases with different values of a rate constant. For the observed kinetic characteristic of alkali gelatinization, the discussions were presented on the basis of amylose complex formation.

The effect of pH and ionic strength on starch–kaolinite interactions

“…Turbidity values are expressed in nephelometric turbidity units (NTU). Starch molecules are anionic, either caused by dissociated -OH group or the presence of fatty acids (Whistler et al, 1984;Chen and Jane, 1994;Yamamoto et al, 2006;Bertuzzi et al, 2007). Thus electrostatic repulsive force arises between the starch macromolecules and the negatively charged mineral particles in iron ore reverse cationic flotation pulps, which are normally in the pH range of 10 to 10.5.…”

Characterization of rice starch and protein obtained by a fast alkaline extraction method

“…According to Yamamoto, Makita, Oki and Otani (2006), under strong alkaline conditions it is known that starch gelatinizes even at room temperature. The starch gelatinization induced by alkali is dependent on the starch type, alkali type, alkali concentration and time and temperature of the treatment (Spigno and De Faveri, 2004).…”

The Effect of Ageing at a Low Temperature on the Rheological Properties of Kahramanmaras-Type Ice Cream Mix

“…[9] The values of n and K are important rheological properties of fluid foods since the flow of these foods is characterized in terms of these quantities. [10] Mainly produced in the southeast Anatolia and preferred due to its unique texture and taste, Kahramanmaras-type is a well-known traditional ice cream variety. Salep is the main stabilizer in this type of ice cream, which gives the preferred taste and texture to the product.…”