Chlorogenic acid and cellulose nanocrystal–assisted crosslinking preparation of a silk-based film to extend the shelf life of strawberries

Water loss is a significant factor in fruit deterioration, and edible films offer a promising method to prevent this. Herein, a silk fibroin (SF)-based edible film reinforced by cellulose nanocrystals (CNCs) and chlorogenic acid (CGA) was developed. CNCs and CGA promote the formation of hydrogen bonds and β-sheets, thereby enhancing hydrophobicity and minimizing water vapor permeability (WVP). Compared with those of pure SF film (water contact angle: 80.3°; WVP: 2.235 × 10−10 g Pa−1 s−1 m−1), the water contact angle of the composite film increased to 90.1° and its WVP decreased to 1.246 × 10−10 g Pa−1 s−1 m−1. Moreover, the tensile strength (27.05 MPa) and Young's modulus (836.53 MPa) of the composite film also increased. Additionally, the antimicrobial activities of the composite film against Escherichia coli and Staphylococcus aureus were 99.66% and 91.07%, respectively. Furthermore, it inhibited the germination of fungal spores (Rhizopus stolonifer). Accordingly, the composite film increased the shelf life of strawberries to 15 d, which is longer than that with other reported films. This study provides an excellent strategy for producing antimicrobial fruit preservation films with high hydrophobicity and low WVP.