Fabrication and characterization of gelatin/carboxymethyl chitosan composite film incorporated with carvacrol and its preservation efficacy in Chinese mitten crab (Eriocheir sinensis)

The demand for active food packaging to enhance the shelf-life of food products is increasing globally. Hence, composite films were fabricated with gelatin (GL) and carboxymethyl chitosan (CC) at different carvacrol (CA) proportions (0, 1, 2, and 3 %). The physical and chemical properties, morphology, molecular characteristics, and bioactivities were investigated. CA markedly improved the thickness, tensile strength, elongation-at-break, and opacity of the films, ranging from 0.12 to 0.17 mm, 26.92–47.46 MPa, 29.15–32.67%, and 1.73–3.88 mm in GL/CC/CA-0 and 3%, respectively (p < 0.05). Moisture content (12.78%), swelling ratio (47.06%), water solubility (40.25), and water vapor barrier (2.55–4.73 × 10−11 g−1 s −1 Pa−1) were significantly reduced in GL/CC/CA-3% films. While the micrographs revealed the even distribution of CA in the GL/CC matrix, its addition did not affect the chemical structure of the matrix according to the Fourier transform infrared and X-ray diffraction results. The antioxidant and antibacterial activities were also enhanced, with the shelf life extended by 3 d in the GL/CC/CA-3%-packaged crab meat. Besides, the inhibition of the abundant spoilers, Pseudoalteromonas, Carnobacterium, and Psychrobacter in the GL/CC/CA-3% group affirmed the promising potential of GL/CC/CA films in preserving crab meats.