Enhancing storage stability of butylated hydroxyanisole/hydroxytoluene antioxidants by encapsulation in oil-in-oil Pickering emulsions

Butylated hydroxyanisole (BHA) and hydroxytoluene (BHT) are among the most widely used antioxidants in the food industry. However, they are susceptible to degradation upon exposures to light, heat, and air during storage, leading to their reduced antioxidative activity even before incorporation into food products. The current approach of stabilizing BHA and BHT by their solubilization in edible oils leaves room for improvement. The present study aimed to improve the storage stability of BHA and BHT by encapsulating them in oil-in-oil Pickering emulsion, with rapeseed oil (RO) containing the solubilized antioxidants as the dispersed phase and silicone oil (SO) as the continuous phase. The impacts of RO volume fraction (i.e. 20–80 %) and Pickering particle size (10–1000 nm SiO₂) on the emulsions’ characteristics were investigated. Of the two variables, the RO fraction was found to have more pronounced impacts as it influenced the antioxidant contents, content uniformity, distribution coefficients of BHA and BHT, and storage stability. The optimal O/O emulsion prepared at 40 vol% RO using 900-nm SiO₂ particles exhibited (i) good colloidal stability, as evidenced by approximately 5 % 24-h creaming index and consistent inter-batch droplet size distribution, and (ii) good storage stability with 90 % recovery of the antioxidant contents after one-month storage at room temperature. The BHA-BHT-loaded emulsion was subsequently incorporated onto silica microparticle carriers, where it exhibited more than twofold improvement in the antioxidant stability, thereby improved antioxidative activity, after three-months storage at 40℃, when compared to conventional BHA-BHT carrier formulations without emulsification.