Extraction, Optimization, Characterization, and Antioxidant Activities of Chinese Wild Rice Nanoparticles

Plant-derived extra-cellular vesicles are a new food resource, rich in functional factors. However, the extraction rate of nanoparticles is low. Therefore, in this experiment, single-factor experiments were carried out using Chinese wild rice as the raw material, and the vesicle-like nanoparticles were successfully extracted from Chinese wild rice. The optimization of Chinese wild rice nanoparticle (WRNP) extraction process was conducted based on the response surface method. When the extraction time was 1 hour (h), and the ratio of material to liquid was 1:8.48 (w/v), the protein concentration of WRNPs was 10.28 ± 0.31 mg/mL after repeated extraction for five times. The obtained WRNPs were characterized, and its stability, antioxidant activity, and cytotoxicity assays were also evaluated. The particle size and zeta potential were 150.40 ± 3.11 nm and −8.95 ± 0.11 mV, respectively. The molecular weight of protein was mainly between 25 and 37 kDa, and the β-folds were the main content in the secondary structure of protein. The nanoparticles remained stable for 22 days at 4 °C, and nanoparticles could be digested by the human body. In addition, the antioxidant activity of WRNPs with a protein concentration of 1.6 mg/mL was not significantly different from that of vitamin C. Finally, nanoparticles have no significant toxic effect. The current study can provide a more perfect method for water frying and a reference for the development of natural antioxidant plant nanoparticles.