Ultrasound application for production of nano-structured particles from esterified starches to retain potassium sorbate

Ultrasound technique was successfully used to obtain nanostructured particles from native and esterified starch, able to support the antimicrobial potassium sorbate (PS). The starch used (native, acetate or oleate) affected the nanoparticles morphology and size: globular or plate like shapes were observed for esterified and native starch respectively, while the hydrodynamic diameters were between 28 and 236 nm, with a trend towards smaller sizes for modified starches. The PS retention capacity ranged from 41.5 -90 mg/g, showing acetylated particles the highest value. The particles were amorphous and had a low average molecular weight of 1.9-6.7 x 10(5) Da. Water retention capacity and solubility (S) were higher for modified starch particles. PS addition had minor effect, increasing S and reducing the apparent amylose content, with respect to particles without sorbate. These results demonstrated that starch modification combined with ultrasound were appropriate strategies to obtain novel and appropriate matrices to retain PS.