The application of deep eutectic solvents systems based on choline chloride in the preparation of biodegradable food packaging films

Nonbiodegradable plastics have brought a variety of issues associated with human health and environmental pollution. Thus, biodegradable films have attracted interest to replace plastics because of their good degradability and rich material supplies. Research on deep eutectic solvents (DESs), which falls under the guidelines of the "Twelve Principles of Green Chemistry", has grown exponentially over the past few years. DESs are new green solvents with excellent chemical tunability that can be used as alternatives to ionic liquids (ILs). Recently, using DESs in the preparation of biodegradable food packaging films has become a research focus. In this review, we summarize the application of choline chloride (ChCl)-based DESs in biodegradable films and discuss the link between ChCl and degradable film materials, with a particular focus on recent advances of ChCl-based DESs in improving film performance. In addition, we also summarize the application of DES extracts in packaging films. ChCl is the most commonly used hydrogen bond acceptor (HBA). ChCl-based DESs exhibit superior performance compared to traditional plasticizers in the production of biodegradable films using natural polymers such as chitosan, starch, and cellulose. ChCl-based DESs can improve the physical-mechanical and barrier properties of films. Therefore, DESs present a new option for improving the functional properties of degradable films.