Micro/nanoparticles containing potassium sorbate obtained by the dialysis technique: Effect of starch concentration and starch ester type on the particle properties

Abstract

Micro/nanoparticles based on native (NTS), acetate (ATS) and oleate (OTS) tapioca starch were produced by dialysis technique as new materials with capacity to support the antimicrobial potassium sorbate (PS). The influence of NTS concentration (0.33, 3.33 and 33.33 mg NTS/mL DMSO) on the particle size and PS content (PSC) was analyzed. Dialysis promoted the disruption of granules and the re-association of the starch producing mainly nanometric particles (<450 nm diameter) when diluted solutions were tested while microparticles (20–200 μm diameter) were obtained from concentrated solutions, probably due to an increased aggregation in systems with high concentration of biopolymer molecules. In addition, the NTS nanoparticles showed an increased capacity to retain PS (6889 - 1372 ppm) than NTS microparticles (1243 - 916 ppm). Starch esterification process modulated physical properties and PSC of the modified particles from ATS and OTS concentrated solutions. The ATS nanoparticles were the systems with the highest PSC (2564 ppm). The average molecular weights (MW) of the resulting particles diminished in comparison with the MW of the NTS, ATS and OTS. All nanometric fractions showed negative z-potential and spherical shape. The developed particles could be applied for food quality optimization, both as carriers of PS for preventing the oxidative degradation or to control the release of this preservative along storage.