Release kinetics and antibacterial activity of potassium salts of iso-α-acids loaded into the films based on gelatin, carboxymethyl cellulose and their blends

Abstract The effect of increasing concentrations (0, 15, 30, and 60 mg/100g) of potassium salts of iso-α-acids (KIAA) on the release kinetics and antimicrobial activity of edible films based on gelatin (GEL), carboxymethyl cellulose (CMC) and their blends (75/25, 50/50, and 25/75) was investigated. Due to the phase separation, the GEL formed microspheres in the 50/50 and 25/75 mixtures. Release of KIAA from the GEL and CMC-rich films was primarily caused by swelling and dissolution, respectively. The pure GEL film offered at least 14 times slower release of KIAA compared to the polysaccharide carrier. The Weibull with Fmax and Gompertz models efficiently predicted the release behavior. The KIAA diffusion mechanism was found to be Quasi-Fickian. The KIAA-added carriers exhibited strong inhibitory effects on E. coli, L. monocytogenes, and S. aureus. The GEL100 system had the best antibacterial effectiveness, likely due to its low pH resulting in high concentration of the undissociated forms of KIAA.