Preparation of mycelial polysaccharide/chitosan composite films of Sanghuangporus vaninii mycelium and its application in blueberry preservation

In this study, the polysaccharide from poplar sap liquid fermented by Sanghuangporus vaninii mycelium (PFP) was extracted via ultrasonic-assisted extraction and further purified using DE-52 cellulose anion-exchange resin to obtain the acidic polysaccharide fraction (APFP). Subsequently, APFP was blended with chitosan (CS) to fabricate a series of composite films with APFP concentrations of 0.25%, 0.5%, 0.75%, and 1% (W/W). Pure CS films were used as controls. The mechanical, barrier, and optical properties, microstructure, and thermal stability of the films were systematically characterized. Meanwhile, their water contact angle, particle size, zeta potential, antioxidant activity, antibacterial activity, and preservation performance for blueberries stored at room temperature were also evaluated. Compared with CS films, APFP-CS films incorporated with APFP exhibited darker color and enhanced mechanical properties. Additionally, the addition of APFP enhanced the antioxidant and antibacterial properties of the CS films. The weight loss rate, decay rate, hardness, soluble solids content, titratable acid content, malondialdehyde (MDA) content, vitamin C (VC) content, anthocyanin content, and total bacterial counts of the blueberries were measured. These results indicated that APFP incorporation could endow CS films with favorable functional properties and bioactivity, and extend the shelf life of blueberries to 15 days. Therefore, the APFP-CS composite films are a promising packaging material for food preservation.