Comparative effects of Berberis vulgaris extract and casein nanocapsules on the antioxidant activity and oxidative stability of selected vegetable oils

This study aimed to enhance the stability and functionality of Berberis vulgaris anthocyanins through casein-based encapsulation and to evaluate their impact on the oxidative stability of vegetable oils. Anthocyanins were encapsulated using 0.25% (w/v) casein at pHs 2, 4.64, and 6. Successful encapsulation was confirmed by FTIR and FESEM analyses. The highest encapsulation efficiency (59.34 ± 3.6%) was achieved at pH 2. Encapsulated anthocyanins exhibited superior antioxidant activity (92.83 ± 0.30%) at pH 7.4 compared to the free extract (86.12 ± 0.11% at pH 2). In simulated digestion, anthocyanin release was higher in gastric fluid (0.11 ± 0.04 mg/L) than in intestinal fluid (0.09 ± 0.05 mg/L), indicating pH- and enzyme-dependent release. When added to vegetable oils, casein-anthocyanin nanocapsules significantly reduced peroxide values after one month of storage: flaxseed oil (4.01 ± 0.06 meq O₂/kg), hemp oil (4.04 ± 0.06 meq O₂/kg), and sweet almond oil (4.37 ± 0.07 meq O₂/kg), while pumpkin seed oil showed a smaller reduction (30.24 ± 0.53 meq O₂/kg). The antioxidant activity of flaxseed oil significantly increased with encapsulated anthocyanins compared to the free extract. These findings demonstrate that casein encapsulation improves anthocyanin stability, controlled release, and oxidative protection in lipid systems.