Association of Branched Dextrin from Nägeli Amylodextrin in Water for Screening of Additives Affecting Starch Gel Properties

Abstract

A novel model system for characterization of double helix in starch is developed using branched dextrin (BD) purified from Nägeli amylodextrin by repeated precipitation in 10% ethanol. The solution of one-time precipitated BD (BD1, 3% in water) starts to develop turbidity in 8 h of incubation at 4°C. Volume particle size distribution during the association of four-time precipitated BD sample (BD4) is analyzed using dynamic light scattering. The mean diameter of the particles jumps from 3.8 to 170 nm between 2 and 2.5 h of incubation, suggesting a prerequisite lag time for maturation of intermolecular association of BD4. Flakes of BD4 in water exhibit a B-type crystal by X-ray diffraction analysis. A screening system of additives affecting turbidity development of BD1 in water is applied for 82 compounds, and sodium tetraborate (borax) significantly retards the development. Borax affects the rate of turbidity development and maximum turbidity at the plateau stage in a concentration-dependent manner. Borax is also added to rice starch gel, which reduces the increase of hardness of the gel during retrogradation. This novel assay system with BD can be used for screening and evaluation of additives affecting starch gelation and retrogradation.