Adipic acid: A green and sustainable crosslinker for innovative food packaging applications

Biopolymer-based food packaging films are a promising eco-friendly alternative to conventional petroleum-based plastics. Adipic acid (AdA) has gained attention as a green and effective crosslinker for improving the performance and characteristics of biopolymer films. AdA (a dicarboxylic acid) is abundantly found in sources such as beets and sugarcane. Its nontoxic nature makes it a suitable candidate for food packaging. Despite its potential, no comprehensive review has studied the progress of applying AdA as a crosslinker in food-oriented biopolymer packaging. To address this gap, this review provides a comprehensive analysis of chemistry and recent advances in the integration of AdA with various polymers for food preservation. This review specifically details the developments in AdA-increased polysaccharide/protein/biopolyester-based packaging films and their role in food preservation. The addition of AdA to biopolymer films improved their mechanical strength, barrier properties, and thermal stability owing to covalent and hydrogen bonds, while also introducing antioxidant activity that helps extend the shelf life of packaged foods. In summary, AdA-crosslinked biopolymer films represent a viable and eco-friendly pathway for food packaging innovation, addressing environmental concerns and consumer demand for safe, sustainable materials.