Preparation of sodium alginate/sodium carboxymethyl cellulose composite coating film and evaluation of its effects on mango preservation.

Abstract

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, sodium alginate (SA) was combined with sodium carboxymethyl cellulose (CMCNa) and ε-polylysine hydrochloride (ε-PLLH) to enhance mechanical and antibacterial properties. Single-factor and response surface experiments optimized the formulation to 1 % SA, 0.5 % CMCNa, 0.2 % ε-PLLH, and 0.4 % glycerol. Structural analyses of the composite film revealed strong intermolecular interactions and improved film stability. Thermogravimetry confirmed enhanced heat resistance, while reduced transmittance limited photodegradation. The composite film inhibited Colletotrichum gloeosporioides, Escherichia coli, and Staphylococcus aureus. When applied to mangoes, the films significantly reduced black spot incidence, weight loss, and respiration rate, delayed declines in firmness, and inhibited malondialdehyde accumulation. Additionally, it increased total phenol and flavonoid contents and boosted antioxidant enzyme activities. In conclusion, the SA/CMC-Na/ε-PLLH film has the potential for practical fruit preservation.