Characterization, antioxidant and antibacterial activities of chitosan/flaxseed soluble dietary fiber/sesamol blend films and their application in pork preservation

Chitosan (CS)-based functional films have been widely used in food packaging and preservation. In this work, we incorporated the sesamol and flaxseed soluble dietary fiber into chitosan solution to make blend films and investigated their mechanical and physicochemical properties, their antioxidant and antibacterial activities as well as their application in pork preservation. The physicochemical properties including optical properties, water solubility (WS), swelling degree (SD), water vapor transmission rate, and mechanical properties were measured. Meanwhile, the effects of flaxseed soluble dietary fiber (fSDF) and sesamol (Sol) on the microstructure of the blend film were further explored using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis. Thereafter, the antioxidant and antibacterial capabilities of CS-based films were evaluated. Moreover, the quality changes, myoglobin, and lipid oxidation during the storage period of fresh pork wrapped with CS-based films were monitored. The results showed that the incorporation of fSDF significantly changed the relatively regular and dense interaction network of CS film itself, which resulted in an improved elongation at break and UV resistance, reduced tensile strength, water resistance, and barrier functions. The addition of sesamol filled up the gaps caused by fSDF and had a smoother and denser structure. Therefore, CS/fSDF/Sol had a better barrier function and water resistance. Besides, sesamol addition significantly increased the antioxidant and antibacterial capabilities. Especially, compared with sesamol-incorporated CS films, sesamol-blended CS/fSDF films exhibited greater antioxidant and antibacterial activities. Finally, when three films (CS, CS/fSDF, CS/fSDF/Sol1.2) were used in the preservation of fresh pork, the CS/fSDF/Sol1.2 exhibited the best performance with the least changes in the appearance, odor, pH values, lipid and myoglobin oxidation levels, and the bacterial contamination. However, the water loss during storage did not improve significantly in pork even coated with CS/fSDF/Sol1.2. In conclusion, we suggest the co-addition of fSDF and sesamol into chitosan films to enhance their functionality in preservation.