Polysaccharides from pineapple peel: Structural characterization, film-forming properties and its effect on strawberry preservation

The growing demand for food safety has stimulated the development of new environmentally friendly food packaging. It is the development trend of food packaging in recent years by using natural polysaccharides as carriers and adding bioactive ingredients extracted from plants to prepare multifunctional films with antioxidant, antimicrobial and biodegradable properties. Herein, three polysaccharide components (PPE40, PPE60, and PPE80) from pineapple peel were extracted by ultrasound-assisted hot water extraction combined with gradient ethanol precipitation method, which all showed a certain scavenging activities against DPPH, ABTS, and hydroxyl radical. Then, the composite films were prepared by adding PPE40, PPE60 and PPE80 to chitosan. The results of SEM, FT-IR and XRD analysis showed that PPE40, PPE60 and PPE80 could interact with chitosan matrix. Furthermore, the addition of PPE40, PPE60, and PPE80 could improve the mechanical properties of the films, and promote the antibacterial activity of the films against B. subtilis, S. aureus and E. coli. Finally, the application of the composite films to strawberries showed that the addition of PPE40, PPE60 and PPE80 could delay the rapid decay of strawberries during storage. The results of this study showed that pineapple polysaccharides have a potential to be applied in the field of food packaging.