Tannic acid one-step induced carboxymethyl chitosan‑sodium alginate-Pickering emulsions multifunctional composite coatings for efficient preservation of strawberries.

Abstract

Postharvest spoilage reduces fruit marketability and shelf life. A multifunctional packaging for strawberries, composed of carboxymethyl chitosan, sodium alginate, tannic acid, and tea tree oil, effectively delays deterioration. It rapidly cross-links via hydrogen bonding within 15 s, forming a protective coating that envelops the fruit surface. This biocompatible film significantly enhances physicochemical properties, antioxidant capacity (with 2% TOCA-TA showing DPPH and ABTS radical scavenging rates of >74% and > 84%, respectively), and antibacterial activity (2%-4% TOCA produces inhibition zones of 15.1-23.9 mm against Escherichia coli (E.coli) and 17.1-26.8 mm against Staphylococcus aureus (S. aureus). It shields against mechanical damage, maintains freshness, reduces dehydration and flavor loss, inhibits microbes, and extends shelf life to seven days. Easy to clean, it ensures a smooth strawberry surface. These findings highlight this polyphenol-induced polysaccharide film as an economical, green strategy for improving perishable food quality and safety.