Preparation, Physicochemical Properties, and Antioxidant Capacity of Edible Agar Films Containing Hull-Less Barley Grass Polysaccharide Extracts

Hull-less barley grass polysaccharide extracts (HBP) are prepared, and the physicochemical and antioxidant properties of agar films with different HBP contents (0, 0.5, 1, 1.5, and 2% w/w of agar mass) are investigated. Infrared spectroscopy shows that HBP interacts with the agar matrix via intermolecular hydrogen bonds. The incorporation of HBP causes rougher surface morphology with increased film thickness (p < 0.05). The films with HBP exhibit decreased brightness with a greenish and yellowish hue. The flexibility of the films is improved gradually as HBP contents increase from 0 to 1.5% w/w (p < 0.05), however, a slight reduction is observed with 2% w/w HBP addition (p > 0.05). The water resistance and surface hydrophobicity of the films are enhanced by adding HBP (p < 0.05). The antioxidant test reveals the strong antioxidant capacity of the HBP-loaded films, which is positively correlated with the HBP contents (p < 0.05), with 2% w/w HBP leading to 59.28% DPPH radical scavenging and 69.00% ABTS radical scavenging. Results suggest that HBP is a promising functional agent for developing antioxidant biopolymer films, and the agar/HBP edible films prepared in this study have potential in food packaging fields.