Preparation and Characterization of Composites of Hydroxypropyl Tapioca Starch and Zein

Hydroxypropyl tapioca starch and zein composites are prepared and the properties of composites are investigated. Starch granules can readily aggregate in the presence of zein to form large granules more than 30 mu m. The total preparation concentration of zein and starch of 45% can be critical, as inferred from the relation between the zein content and the particle size of the composite. An increase of zein content or reaction time allows the starch granules to be adhered with zein, wrapped by zein, or even be embedded in the zein matrix. The characteristic peaks of zein shifting to the lower wavenumber and that of hydrogen bonds moving to higher wavenumbers in the Fourier transform infrared spectroscopy indicate the interaction between zein and starch. Zein reduces the viscosity, increases gelatinization temperature, and decreases gelatinization enthalpy of the composites compared with that of starch. This insight may be helpful in designing and preparing composites of zein and starch with promising properties.