Effects of beeswax emulsified by octenyl succinate starch on the structure and physicochemical properties of acid-modified starchfilms

This work aimed to develop a novel strategy to modulate the distribution of beeswax in acid-modified starch films via tuning octenyl succinate starch (OSS) ratios and to elucidate their structure-property relationships. The apparent viscosity and storage modulus of the film-forming solution decreased with the increase of OSS ratio. Attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy revealed that the hydrogen bond in the film-forming network was cleaved with the presence of OSS. Scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD) demonstrated that OSS ratio had an obvious effect on the formation and distribution of beeswax crystal particles. Uniform distribution of beeswax effectively enhanced the hydrophobicity and water barrier properties of films and performed preferable elongation at break but at the expense of tensile strength and optical properties. The films with higher OSS ratio (>12 %) presented higher thermal stability. This study provides new information on the rational design of emulsified films to obtain desirable physicochemical properties by tuning the distribution of beeswax.