Corn starch nanoparticles obtained via wet-stirred media milling: Structural characterization and interfacial activity at the O/W interface

Abstract

Polysaccharide-based nanoparticles have emerged as novel stabilizers in Pickering emulsions. Techniques such as wet-stirred media milling (WSMM) to obtain starch nanoparticles have not been widely reported, in contrast to the chemical hydrolysis methods. Hence, this contribution aimed to analyze: 1) the effect of WSMM, and of the different concentrations of SDS (sodium dodecyl sulfate) (0, 0.07 and 1 % w/v) added during milling as stabilizer, on the structural changes of starch; 2) the impact of these structural changes on the dynamic interfacial properties, and on the short-term physical stability of Pickering emulsions. The starch nanoparticles developed with the highest proportion of SDS added during milling (7 % w/v S + 1 % w/v SDS) showed an improved physical stability in suspension after one month (289 nm), starting from an initial size of 14.08 ± 0.08 μm. XRD and FTIR techniques evidenced a lower crystallinity degree as a consequence of milling. Amylose-SDS complexes with amphiphilic character were formed during milling, which explained the enhanced wettability, redispersion and interfacial properties at the O/W interface. These observations might account for the physical stability of oil droplets (average size of 292 nm after one month) of Pickering emulsions, whose in-vitro digestion behaviour highlighted their potential to control fat intake. These results suggested that WSMM could be implemented as a solvent-free methodology to obtain polysaccharide-based nanoparticles.