Effect of ε‐polylysine on properties of chitosan‐anthocyanin films for food packaging

Abstract In this study, the chitosan (CS) was combined with purple tomato anthocyanin (ATH) and ε‐polylysine (PL) to prepare CS/ATH/PL films with PL concentrations of 0%, 1%, 3%, 5%, or 7%. In which, ATH and PL were used as the pH indicator and the antimicrobial agent, respectively. The effect of PL content on the physiochemical properties of CS/ATH/PL films, as well as the application in pork packaging, was investigated. Adding PL improved the color stability of ATH in the films. For instance, at 40°C, the retention index of ATH increased from 82.13% (for CS/ATH/0%‐PL) to 91.01% (for CS/ATH/7%‐PL); under UV radiation, it increased from 62.56% (for CS/ATH/0%‐PL) to 88.23% (for CS/ATH/7%‐PL). The doped PL significantly improved the elongation at break, antioxidant and antibacterial properties, and barrier properties against water vapor, while PL had no significant effect on the water content of the films. Compared with the control, the pH, total viable count (TVC), and total volatile basic nitrogen (TVB‐N) of pork packaged by CS/ATH/PL films were effectively delayed during storage. The CS/ATH/7%‐PL film had the best preservative effect on the pork, and the most significant visual color change for monitoring the pork freshness on 0–4 days. Therefore, the CS/ATH/PL films with higher content of PL content have potential application prospects in active and intelligent packaging. Highlights ε‐Polylysine (PL) improved the color stability of anthocyanins in chitosan‐based films. Barrier, antioxidant, and antibacterial properties of films increased with PL content. PL‐7% films are promising for active and intelligent packaging for pork.