Fast water absorption and antibacterial konjac glucomannan/xanthan gum/carboxymethyl cellulose film incorporated with rosmarinic acid for extending shelf life of chilled pork

Abstract

Blended films composed of konjac glucomannan (KGM), xanthan gum (XG), and carboxymethyl cellulose (CMC) (denoted as KXC), enriched with varying concentrations of rosmarinic acid (RA) (denoted as KXC-RA), were prepared by casting and characterized for their physicochemical properties. The KXC films demonstrated good mechanical properties in both dry (tensile strength (TS): 60.1–78.0 MPa; elongation at break (EAB): 26.5–33.4 %) and wet states (TS: 0.20–1.02 MPa; EAB: 76.0–168.4 %), due to strong intermolecular interactions forming a physical crosslinked network. The films also exhibited rapid water absorption (9.2–12.6 g g⁻¹ min⁻¹ in the first minute) and high swelling capacity (equilibrium swelling ratio of 38.6–45.2 g g⁻¹), owing to the excellent water retention properties of CMC. The incorporation of RA significantly enhanced the films' antibacterial and antioxidant activities, with maximum inhibition rates against S. aureus and E. coli reaching 98.3 ± 0.41 % and 96.2 ± 0.29 %, respectively. When used as absorbent pads for chilled pork, the KXC-RA films significantly reduced pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBA), and total viable count (TVC) compared to blank and commercial pads. After 24 h of storage, minimal quality deterioration was observed, and the KXC-RA films extended pork shelf life to 7 days at 4 °C, exceeding the 5-day shelf life provided by commercial pads (based on TVC <6 log₁₀ CFU/g). These findings highlight the promising potential of KXC-RA films for both short- and long-term preservation of chilled pork.