Rice bran protein-based nanoemulsion carrier for improving stability and bioavailability of quercetin

Rice bran protein with good hydrophilicity and high surface activity was utilized as an emulsifier to stabilize nanoemulsions. In this experiment, under the conditions of 3% RBP content and pH 9.0, the rice bran protein-based nanoemulsions (RBP NEs) were shown to possess the smallest droplet size and the best stability. Adding quercetin at 3 mg/mL under these conditions led to the formation of nanoemulsions with a smaller droplet size and a higher incorporation rate. The quercetin-loaded rice bran protein-based nanoemulsion (QE-RBP NEs) demonstrated good stability under alkaline conditions and low salt ion concentrations. After in vitro digestion and cell penetration experiments, it was concluded that encapsulation in the RBP NEs led to an increased quercetin bioavailability, which reached 12.70 +/- 0.12%. The nanoemulsion encapsulation also reduced the toxicity of quercetin to cells and increased the cell penetration of quercetin, which reached 4.93 +/- 0.01 x 10(-6) cm/s. In addition, both RBP NEs and QE-RBP NEs have a storage period of 14 days. This work confirms that RBP NEs can be used as an effective carrier to deliver biologically active molecules.