Abstract: The effects of in vitro gastrointestinal digestion on the controlled release and antioxidant properties of encapsulated grape skin anthocyanins (ACNs) from water-in-oil-in-water (W1/O/W2) double emulsions were determined. The double emulsions exhibited a bimodal distribution (d = (149.33 ± 1.44) nm) with an encapsulation efficiency of (82.99 ± 2.38)%. Oral digestion in vitro did not affect the structure of the emulsion droplets. After simulated gastric digestion, the double W1/O/W2 emulsions became a single W1/O emulsion due to proteolysis, and the released emulsion droplets were aggregated together leading to a significant increase (P < 0.05) in average droplet size. During subsequent intestinal digestion, the W1/O droplets were broken, so that the average droplet size (d < 150 nm) decreased significantly (P < 0.05), and the highest antioxidant activities were identified. Our results indicated that the encapsulated ACNs were effectively protected by the W1/O/W2 double emulsions against in vitro oral and gastric digestion, and were delivered to the target in the simulated small intestine.

Key words: anthocyanins, W1/O/W2 double emulsions, controlled release, in vitro digestion, casein sodium