Preparation and stability of resistant starch nanoparticles, using acid hydrolysis and cross-linking of waxy rice starch

To develop resistant starch (RS) nanoparticles, waxy rice starch was hydrolyzed with acid for 10 days, and acid-hydrolyzed waxy rice starch (AHW) was cross-linked with sodium trimetaphosphate. The RS nanoparticles were collected by freeze-drying (FD), freeze-drying after sonication (SFD), and ethanol dehydration after sonication (SE). The particle size distribution, RS level by modified AOAC, zeta potential, and stability of dispersion were assessed. The hydrolysis rate ranged from 44.62% to 49.43%, and AHW particle size decreased as hydrolysis time increased. All AHW and RS nanoparticles showed A type crystallinity. The particle size and zeta potential of the nanoparticles dried by FD, SFD, and SE were 300.0, 211.9, and 459.7 nm and -37.1, -43.0, and -35.4 mV, respectively. The RS levels were increased by cross-linking. The SFD dispersion was the most stable. The results indicate that the RS4 nanoparticles, for applying to liquid foods, can be prepared by acid hydrolysis, cross-linking, and SFD.