Controlled release of water-soluble astaxanthin from carboxymethyl cellulose/gelatin and octenyl succinic anhydride starch/gelatin blend films

The effect of increasing concentrations (0, 0.25, 0.5, 1%) of commercial water-soluble AstaSana astaxanthin (AST) on the physicochemical properties, release kinetics and antioxidant activity of binary 75/25 carboxymethyl cellulose/gelatin (CMC75/GEL25) and octenyl succinic anhydride starch/gelatin (OSA75/GEL25) blend films was investigated. The microscopic observations showed that the obtained blends were phase-separated systems. Regardless of the AST concentration, the CMC-based films were more opaque, stronger, and less stretchable than the OSA-based films. The AST-supplemented films exhibited an intensive red color. The starch granules (from the AST formulation) contributed to high roughness and opacity of the films. The presence of AST contributed to a significant decrease of the puncture strength and oxygen permeability of the CMC-based film. The AST-supplemented films did not differ in terms of the water vapour barrier properties. Due to the low quantity of astaxanthin in the systems, the Fourier-transform infrared spectra of the control and AST-supplemented films were similar. The increase in the AST concentration was accompanied by reduced solubility and increased swelling of the OSA-based films, while an opposite result was observed for the CMC-based films. According to the Korsmeyer-Peppas with time lag model, the AST release kinetics exhibited quasi-Fickian behaviour. Due to their weaker solubility, the OSA75/GEL25 films offered at least 7 times slower release of AST than the CMC-based carrier. The times required for 25% AST release from the CMC75/GEL25 and OSA75/GEL25 films were 1.20–1.74 and 12.60–20.04 min, respectively. A high positive correlation (R2 = 0.78–0.91) was found between the AST release and antiradical activity of the films.