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 ASTsupplemented 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 quasiFickian 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.

Automated summary

This study investigated the effects of different concentrations of AST on the properties, release kinetics, and antioxidant activity of blend films. Regardless of the AST concentration, CMC-based films were more opaque, stronger, and less stretchable than OSA-based films, with an intense red color when supplemented with AST. The presence of AST significantly decreased the puncture strength and oxygen permeability of CMC-based films, while not affecting water vapor barrier properties. AST release kinetics showed quasiFickian behavior, with OSA-based films releasing AST at a slower rate compared to CMC-based films, with a high positive correlation between AST release and antiradical activity.