Development of active packaging film based on quaternary chitosan and procyanidin-g-guar gum

The development of active packaging films based on polysaccharides and plant-originated polyphenols has emerged in recent years. However, the low stability of polyphenols greatly limits the practical use of polysaccharide/polyphenol films. Recently, studies have revealed that the stability of polyphenols can be elevated by grafting them with biomacromolecules. In this study, a typical polyphenolic compound, procyanidin (PA), was covalently linked to guar gum (GG) through graft copolymerization. The synthesized PA-g-GG was characterized by UV–vis, FT-IR, ¹H NMR spectroscopy, and TGA. Afterwards, PA-g-GG was incorporated into a quaternary chitosan (QC)-based film matrix to obtain QC/PA-g-GG film. QC/PA-g-GG film was characterized for its structure, physicochemical properties, and antioxidant and antibacterial activities. The results showed that PA-g-GG had a UV absorption at 280 nm, an IR absorption at 1610 and 1520 cm⁻¹ ,and a proton peak at 6.8 ppm, indicating that PA was successfully grafted with GG. PA-g-GG presented a higher stability than PA. The QC/PA-g-GG film had a smooth surface and compact inner structure. PA-g-GG and QC formed hydrogen bonds within the film. PA-g-GG increased the barrier ability of QC film against UV–vis light, moisture, and oxygen gas. In addition, PA-g-GG enhanced the tensile strength, elongation at break, and antioxidant and antibacterial activities of QC film. In conclusion, the QC/PA-g-GG film has a good active packaging potential in the food industry.