FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Profile of modified waxy maize starch systems


The objective of this paper was to evaluate some selected physicochemical properties of modified waxy maize starch investigated individually and, also, in mixtures. The investigations comprised three preparations of waxy maize starch and their mixtures in 1:1 ratio, namely Clearam, Pregeflo, and C*Tex. The physicochemical properties of the starches and their mixtures were investigated. The swelling power and solubility in water at 20, 60 and 80 °C, as well as the retrogradation degree, and syneresis were determined. Additionally, the pasting profile of 7 % starch – water dispersions was analysed. The rheological properties of 5 % starch pastes were investigated in a rotational rheometer with co-axial cylinders applied as a measuring element. The flow curves of the starch pastes were plotted and described by Herschel-Bulkley and Ostwald de Waele models. The area of thixotropy hysteresis loop and the reconstruction degree of structure of the starch pastes investigated were also calculated. Based on the investigations accomplished, it was concluded that the starches studied differed in their physicochemical properties. The highest swelling power exhibited the Clearam starch, whereas C*Tex – the lowest. The Pregeflo preparation was characterized by the highest solubility in water, whereas the Clearam starch showed the lowest solubility level. Among all the tested mixtures, Clearam and C*Tex had the poorest solubility in water. All the starch preparations and their systems achieved their maximum swelling power and solubility in water only at a temperature of 80 °C. The gels analysed showed a very good stability during the storage at 6 °C. There were no retrogradation phenomena nor syneresis symptoms during the storage period under investigation. Significant differences in the profile of pasting of the preparations analysed were found. The Pregeflo starch pasted already at a temperature of 25 °C. The Clearam preparation exhibited both the low pasting temperature and the low peak viscosity temperature. The Clearam starch had a maximum viscosity value that was twice as high as the viscosity of other preparations. All the starches were characterized by a very good resistance to heating. After cooling, they achieved a viscosity value equalling the peak viscosity value or higher. The pastes of starches investigated were non-Newtonian and shear thinning fluids, and they exhibited yield stress and thixotropy phenomena. Interactions between Clearam and C*Tex, as well as between Clearam and Pregeflo were found. Those interactions manifested themselves in the fact that a structure of a higher shear resistance was formed. The reconstruction degree of all the starch pastes investigated ranged from 70.1 %, as for the Pregeflo preparation, to 96.2 %, as for the C*Tex starch.


waxy maize starch, chemically modified starch, physicochemical properties