Controlled fabrication, structure and property of lysozyme composite antibacterial film immobilized by calcium alginate-gelatin.

Abstract

Incorporating lysozyme as a preservative in food products faces challenges in the complex food environment, leading to reduced efficacy. Cross-linking sodium alginate with Ca2+ forms an intricate "egg box" network, ideal for carrying bioactive compounds. This study combined gelatin with calcium alginate to enhance the composite matrix's mechanical strength for lysozyme immobilization. The research assessed lysozyme immobilization efficiency, physicochemical properties, and antibacterial effectiveness of the calcium alginate-gelatin-lysozyme (Ca-ALG-Gel-LYS) composite film. Results showed unchanged lysozyme structure post-immobilization, with improved storage stability. The composite film exhibited compatibility without phase separation and had a water solubility of only 3.53 %. It also exhibited improved barrier properties and mechanical strength, with light transmittance nearly zero at 200-300 nm. Over an 8-h period, inactivation rates for S. aureus, L. monocytogenes, E. coli, and Salmonella were 3.42, 3.73, 2.66, and 2.90 log CFU/mL, respectively. Overall, immobilizing lysozyme in the cross-linked film enhanced its performance.