Formulation of Sustainable Biopolymer-Based Nanoparticles Obtained via Media Milling for Chia Oil Vehiculization in Pickering Emulsions

Abstract

Sustainable corn starch nanoparticles were prepared using media milling to stabilize omega-3-rich Pickering emulsions based on chia oil. The milling conditions were as follows: 24 h (milling time), 0.4–0.6 mm (bead diameter), 1600 rpm (impeller speed), 30% (volume occupied by the grinding media), 7% w/v (starch concentration), and 0, 0.07 and 1% w/v of sodium dodecyl sulfate (SDS). Nanosuspensions containing 7% w/v of starch and the three concentrations of SDS were filtered, centrifuged, homogenized, and spray-dried to obtain redispersible powders. The particle size ranges were 2288 ± 211, 385 ± 21, and 278 ± 11 nm with 0, 0.07 and 1% w/v of SDS, respectively. The most stable backscattering profiles obtained during a period of one week were observed with 0.07 and 1% w/v of SDS. Therefore, the surface dilatational rheology of these particles adsorbed at chia oil/water interfaces was studied. A rapid decrease in the interfacial tension within 1 h was obtained with 1% w/v of SDS (down to 3 mN/m). Moreover, the most stable particle size after redispersion was obtained with the highest concentration of SDS. Finally, Pickering emulsions were prepared, and significant coalescence was observed with 0 and 0.07% w/v of SDS (within a few minutes). Nonetheless, in the presence of 1% w/v of SDS, oil droplets showed mean diameters and polydispersity indexes of 280.13 ± 4.60 nm and 0.35 ± 0.02, respectively, with no significant variations during storage for around 1 month. The results show that wet-stirred media milling can be applied to produce sustainable, new food-grade starch nanoparticles able to deliver bioactive compounds from chia oil.

Keywords

• chia oil
• corn starch
• nanoparticle
• Pickering emulsion
• wet-stirred media milling