Optimization of Ultrasonic Extraction, Functional Properties, and Antioxidant Activity of <i>Naematelia aurantialba</i> Polysaccharides

Abstract Naematelia aurantialba ( N. aurantialba ) is a fungus rich in polysaccharides with medicinal and edible properties. Polysaccharides are the main active components of N. aurantialba ; however, their biological activities and functional properties have not been widely explored. In this study, the ultrasonic extraction process for N. aurantialba polysaccharides (NAP) is optimized, and the physicochemical, functional, and antioxidant activities of the homogeneous fraction (NAP) are investigated. The optimal extraction conditions are a liquid–solid ratio of 50 mL g −1 , ultrasonic power of 430 W, ultrasonic time of 32 min, resulting in an extraction rate of N. aurantialba polysaccharides of 48.68% ± 0.83%. NAP has a molecular weight of 915 kDa. The monosaccharide composition of NAP is as follows: mannose (59.04% ± 0.12%), xylose (23.89% ± 0.03%), glucuronic acid (14.07% ± 0.24%), galacturonic acid (2.12% ± 0.02%), and glucose (0.76% ± 0.02%). NAP exhibites water and oil retention capacities of 14.62 ± 0.25 g g −1 and 23.73 ± 0.85 g g −1 , respectively. Furthermore, NAP demonstrates favorable moisture absorption and retention properties. The results show that NAP has a significantly stronger antioxidant effect, as demonstrated by its concentration‐dependent scavenging of ABTS, DPPH, and hydroxyl radicals.