Characterization of Zizania latifolia polysaccharide-corn starch composite films and their application in the postharvest preservation of strawberries

This study aimed to prepare a composite film with antioxidant activity for postharvest strawberry preservation. Three water-soluble polysaccharides (F1, F2, and F3) were purified from Zizania latifolia. Based on their anti-oxidant activities, polysaccharide F3 (2557 kDa) was selected to prepare corn starch (CS) and Z. latifolia poly-saccharide (ZP) composite films by tape casting, and the film properties were evaluated. Results revealed that the swelling degree and elongation of the films were significantly increased with the addition of ZP, while the ZP-containing films had lower light transmittance (0.64-2.13%). The highest tensile strength was observed for the 4% ZPCS film. Microstructurally, scanning electron microscopy results indicated that ZP and CS were compatible. At the same time, Fourier transforms infrared spectroscopy revealed the presence of intermolecular hydrogen bonds between ZP and CS, forming a dense structure. In addition, composite films with ZP contents were used for strawberry preservation. When stored for 18 d, the weight loss rate, malondialdehyde content, and soluble solid content of strawberries packaged in the 6% ZPCS composite film decreased by 33.6%, 23.68%, and 12.96%, respectively, compared with polyethylene packaging. Results suggest that the ZP composite film could be used to prolong shelf-life and maintain the postharvest quality of strawberries.

Automated summary

The objective of this study was to develop an antioxidant composite film for postharvest strawberry preservation. Three water-soluble polysaccharides (F1, F2, and F3) were extracted from Zizania latifolia. Polysaccharide F3 (2557 kDa) was selected based on its antioxidant activity to prepare corn starch (CS) and Z. latifolia polysaccharide (ZP) composite films. The addition of ZP increased the swelling degree and elongation of the films, but decreased light transmittance. The ZP composite film with 6% content showed improved preservation effects on strawberries compared to polyethylene packaging.