Nanoencapsulation of wheat germ oil with chitosan-nettle seed gum-ovalbumin: Preparation, optimization, and characterization

This study was aimed to optimize nanoencapsulation conditions of ovalbumin (OV)-nettle seed gum (NSG)-chitosan (CS), ONC-based nanocarriers, using response surface methodology (RSM). Then, wheat germ oil (WGO) was encapsulated in optimized ONC nanocarriers, and WGO-loaded nanocarriers were characterized for their encapsulation efficiency, zeta potential, average particle size, emulsion stability, thermal, structural, micromorphological, rheological, and cytotoxic properties. The results showed that NSG-CS amount of 30 mL, OV amount of 20 mL, and pH of 3 gave the maximum zeta potential and minimum average particle size based on the predicted conditions for the production of ONC nanocarriers by RSM. Encapsulation efficiencies of WGO-loaded nanoparticles (WGONs) containing different ratios of WGO (2.5% to 4.5%, v:w) ranged from 48.66% to 71.91%. According to rheological properties, both the solutions of ONC complex and WGONs exhibited Newtonian flow behavior. The FT-IR spectra exhibited changes in the peaks associated with amino and carboxyl groups following the encapsulation of WGO, suggesting the successful completion of the encapsulation process. SEM images revealed that the addition of WGO into the capsule resulted in the formation of rough particles. The cytotoxicity tests demonstrated that concentrations of WGO, CS, NSG, OV, WGO, ONC, and WGON up to 10 mg mL^–1 did not significantly reduce the viability of L-929 human fibroblast cell lines, indicating their nontoxicity toward healthy cells. In conclusion, this study suggested the successful encapsulation of WGO within ONC carriers at the nanoscale, achieving high encapsulation efficiency and favorable properties to enhance their uses for different purposes.

Practical Application: Wheat germ, an important by-product of wheat milling industry, contains considerable amounts of oil which possesses many beneficial components like tocopherol, vitamin B, phytosterols, and policosanols. These compounds have potential health benefits such as supporting exercise performance, cardiovascular health, and reducing the risk of overweight/obesity. Therefore, this underutilized oil needs to be introduced to the food/nutraceutical industry more extensively. However, the susceptibility of wheat germ oil (WGO) to oxidation and its short shelf-life limit its further use. Encapsulation technology can be employed to protect the WGO, extend its shelf-life, and improve its stability. Response surface methodology (RSM) is also a versatile way to determine the optimal conditions for encapsulation, resulting in the formation of stable nanocapsules containing WGO. The resulting nanocapsules effectively release the active ingredients of WGO, protecting them from oxidation and making them highly suitable for use as functional food ingredients or in pharmaceutical products with promising potential.