Preparation of Gallic Acid-Grafted Silkworm Pupae Chitosan Composite Film and Its Application in Blueberry Preservation

Chitosan films are promising for food packaging but are limited by poor solubility, weak mechanical strength, and insufficient functional properties. Most conventional chitosan is derived from crustacean shells, with limited exploration of alternative biosources. To overcome these drawbacks, this study utilized silkworm pupae chitosan as a substrate and graft-modified it with gallic acid (GA-g-CS) to develop functional composite films for blueberry preservation. The results showed that the synthesized GA-g-CS exhibited a grafting efficiency of 83.8%. Compared to chitosan films, the GA-g-CS composite films showed enhanced physical properties, mechanical properties, UV-blocking capacity, antioxidant activity, and antimicrobial activity. Water solubility increased by 21%, and water vapor permeability was reduced by approximately 91%. In blueberry preservation trials, GA-g-CS composite films reduced weight loss by 12%, decreased decay incidence by 30%, and better maintained firmness and nutritional content. This study modified silkworm pupae-derived chitosan to overcome the inherent limitations of native chitosan. The resulting GA-g-CS film represents a high-performance active packaging material with significant potential. The resulting GA-g-CS film represents a high-performance active packaging material with potential for preserving perishable foods prone to oxidation and spoilage.