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Physicochemical properties of waxy corn starch after three-stage modification

2016; Elsevier BV; Volume: 62; Linguagem: Inglês

10.1016/j.foodhyd.2016.08.010

1873-7137

Marzena Włodarczyk-Stasiak, Artur Mazurek, Radosław Kowalski, Urszula Pankiewicz, Jerzy Jamroz,

Microbial Metabolites in Food Biotechnology

The paper presents a study on the functional properties of waxy corn starches, physicochemically modified. The physical modifications (hydrothermal treatment) allowed to obtain pre-gelatinised starch (Merigel) or untreated starch, of cook-up type (Resistamyl). The chemical modification of starches differentiated them in terms of the degree of cross-linking (low, medium and high) and the level of substitution (medium). The characteristics of changes in the viscosity of starch gels were determined in the function of temperature and time. It was found that with an increase of the degree of cross-linking (low < medium < high) the viscosity of starches of the pre-gelatinisation and cook-up types decreases. At the temperature of +20 °C starch gels of the Merigel type are characterised by a high level of transparency, which may indicate intensively hindered retrogradation at +4 °C, while measurements for samples of the Resistamyl type indicate transmittance values close to zero, similar to those for waxy corn starch. The tendency to syneresis was tested at +4 °C and −22 °C. At +4 °C, the modified starch gels, type Merigel, are characterised by nearly three-fold higher degree of syneresis compared to those from the Resistamyl group. The degree of syneresis of cook-up type gels is small after storage at 22 °C. Starches of the pre-gelatinisation type are characterised by WAI (Water Adsorption Index) values in the range of 981–1207%, and starches of the cook-up type - 196–205%. Higher values of FAI (Fat Adsorption Index) are also noted in the case of the pre-gelatinisation starches (FAI: 194–222%) in relation to the cook-up type starches (FAI: 170–174%). Cook-up starches do not form emulsions. The medium degree of cross-linking of pre-gelatinisation type starches causes a lowering of the value of their specific surface area (SBET), while for the cook-up type starches an increase of that value was observed.