Exploring orange peel treatment with deep eutectic solvents and diluted organic acids

The disintegration of orange peel waste in deep eutectic solvents and diluted organic acids is presented in this work. The albedo and flavedo layers of the peel were studied separately, showing faster disintegration of the latter. Addition of water to the deep eutectic solvents lowered the amount of remaining solids and improved the disintegration times. These improvements are subscribed to a decrease in viscosity upon deep eutectic solvent dilution. Each of the individual deep eutectic solvent components were diluted and subjected to the same disintegration tests. The corresponding diluted organic acids showed similar orange peel disintegration performance as the tested deep eutectic solvents, whereas dilutions of the other counterparts did not show any activity. Hence, the active deep eutectic solvent components during orange peel treatment are considered to be their organic acids. Flavonoids and essential oils were released during the treatment, offering new opportunities for the development of orange peel waste valorisation routes.