Carboxymethyl hemicellulose/sorbitol/gallic acid green composite films for fresh fruit preservation

Abstract

Fruits are prone to deterioration during transportation and preservation, while conventional packaging materials generally pose a persistent threat to the environment. In the present study, a multifunctional green composite film was developed using solution casting method through the interactions of hydrogen bonds among carboxymethyl hemicellulose, sorbitol, and gallic acid, which was subsequently employed as functional materials for fresh fruit preservation application. In particular, the influence of the degree of substitution (DS) of carboxymethyl hemicellulose on the properties of the composite films was investigated. The results indicated that as the DS increased, the carboxymethyl hemicellulose/sorbitol/gallic acid composite film demonstrated a notable improvement in transmittance, air barrier property, and antibacterial activity. Specifically, the composite film (DS = 0.59) showed a 42.54 % increase in transmittance and a 48.31 % decrease in air permeability compared to the composite film containing hemicellulose (control sample). Furthermore, the composite film (DS = 0.59) displayed a desired inhibition effect against Staphylococcus aureus. Based on the 9-day blueberry preservation test, the composite film (DS = 0.59) exhibited a weight loss rate of 15.36 %, whereas the blank group retained a value up to 20.34 %. In addition, the increased DS was found to lead to the decreased tensile strength but improved elongation at break. Overall, the carboxymethyl hemicellulose/sorbitol/gallic acid green composite films, derived from natural bio-materials and free of environmental concerns, could hold great promise as a novel packaging material for fresh fruit preservation.