Konjac glucomannan/ carboxylated cellulose nanofiber-based edible coating with tannic acid maintains quality and prolongs shelf-life of mango fruit

Polysaccharide films containing antimicrobial agents have good prospects for application in the fruit industry. However, poor film-forming properties of polysaccharides remain a major challenge. In this work, the konjac glucomannan (KGM) was modified by cross-linking with carboxylated cellulose nanofibers (CNF) to form a composite coating film, and tannic acid (TA) was provided as an active ingredient to improve the antibacterial effect. The optimal formula was: CNF/KGM (w:w) 3.05:10, TA content was 0.40 %, and glycerol content was 0.57 %. KGM/CNF/TA film had good compatibility and a compact structure. The thermal stability and water contact angle of the composite film were higher than those of KGM. Furthermore, the KGM/CNF/TA film reduced the black spot incidence, maintained fruit firmness, decreased ethylene release and respiration rate, increased the antioxidant enzyme activities, and extended the shelf-life of mango. Thus, KGM/CNF/TA is expected to expand polysaccharide/ polymer composite application in the fruit industry.