Optimization of ultrasound-assisted deep eutectic solvent extraction of betanin and its application in chitosan-based biofilm

A red dragon fruit peel (DFP) contributes to 30-35% of total fruit weight and is disposed of as waste by the fruit processing industries, despite the fact that it contains bioactive compounds with nutritional properties. Ultrasound-assisted deep eutectic solvent (DES) extraction of DFP was performed for the extraction of betanin. From the parametric study, ChCl-ethylene glycol was chosen for further optimization. Extraction parameters were screened using the Plackett-Burman design. Box-Behnken design was applied to get the optimum condition of 40% cycle time, 40% water concentration, and 5 min extraction time to obtain total betanin content of 10.2 mg/10 g dry wt. DFP was valorized to chitosan-based antioxidant films. % DPPH, and % ABTS radical scavenging activity of extract incorporated film was better than control film. Thermogravimetric analysis (TGA) confirmed biofilms could be used safely at food temperature (up to 145 ?). FTIR analysis confirmed the functional group of extract in the chitosan films. With the addition of DES extract, the water vapor permeability and water solubility increased to 3.59 x 10(-10) g m(-1) s(-1) Pa-1 and 47.03%, respectively. The thickness of the film also increased because of the enlargement of space between polymer chains. The elasticity of the films increased by 192.40%, indicating that the DES extract was successfully incorporated as a plasticizer. The tensile strength decreased to 12.46 MPa because of the interaction of DES with the -OH group of chitosan, which disrupts polymer chain bonds. Therefore, bio-refining of waste peel can be advantageous for managing waste disposal and reducing plastic pollution.