Effect of acid hydrolysis and OSA esterification of waxy cassava starch on emulsifying properties in Pickering-type emulsions

The emulsifying properties of waxy cassava starch modified by acid hydrolysis and esterification with octenyl succinic groups in Pickering-type emulsions were evaluated using zeta potential, emulsification index, light microscopy and rheology behavior. The optimal conditions of acid hydrolysis to achieve the highest emulsification index were determined to be a hydrochloric acid concentration of 4 mol/L for 5.20 h. After that, the starch was esterified to obtain a double modification. The emulsification index values were acid treated/succinated starch > optimal acid treated starch > native starch. The acid treated/succinated starch emulsion presented higher storage modulus (G′) values, without G' and loss modulus (G”) crossing point in the evaluated frequency range. Acid hydrolysis modified the emulsifying properties of waxy cassava starch improving its interaction at the oil/water interface. According to observations by light microscopy and rheology behavior, the double modification formed a more uniform and stable network over time through granule-granule and granule-interface interactions.