Physicochemical characterization of bioactive polysaccharides from three seaweed and application of functional fruit packaging films.

Seaweed polysaccharides show tremendous research and application value because of their significant and unique biological activities. However, reports on seaweed polysaccharides usually focus on in-depth studies of a specific biological activity, which severely limits their further development. Herein, three seaweed polysaccharides were isolated from Undaria pinnatifida (UPPS), Sargassum pallidum (SPPS), and Ulva lactuca (ULPS), respectively. The physicochemical properties, structure, rheological properties, antioxidant activities, antibacterial activities, and anti-glycation activities of UPPS, ULPS, and SPPS were comprehensively studied. It was first demonstrated that SPPS and UPPS had triple prominent biological activities. SPPS exhibited the best biological activities in antioxidation (IC in the ABTS test: 0.4616 ± 0.0134 mg/mL), antibacterial effect, and anti-glycation activity (inhibitory rate: 84.74 ± 0.07 %). Additionally, UPPS films (UPPSF) demonstrated superior ultraviolet shielding performance, lower water vapor permeability (1.78 ± 0.01 g/m·s·Pa × 10), higher hydrophobicity (water contact angle: 96.91 ± 2.52°), and higher antioxidant activity compared to ULPS films (ULPSF). UPPSF and ULPSF effectively prolonged the shelf life of strawberries to six days, and UPPSF showed better preservation properties. This work provides novel theoretical insights into the use of polysaccharides as medicinal nutraceuticals, bioactive agents, and food packaging films.