Sequential extraction of hesperidin, pectin, lignin, and cellulose from orange peels: towards valorization of agro-waste

To maximize the reuse of citrus fruit processing waste, which is generated in large amounts due to juice production, this work shows the results of a new renewable approach for the extraction of high-added-value compounds present in orange biomass, specifically in orange peels (OP). The method is based on the use of diluted Ca²⁺, acid, and base solutions for the extraction of hesperidin (HSD), pectin, lignin, and cellulose sequentially, without generating any organic solid waste at the end, and without the need for air drying the starting biomass. Good yields of hesperidin were recovered (~1.56%), with excellent purity (up to 95%), as well as lignin (yield ~2.2%) and cellulose (yield ~12%). Pectin obtained by this process showed a high amount of galacturonic acid (~88%) and a low degree of methylation (~16%). All products were thoroughly characterized by applying Fourier transform infrared (FTIR) spectroscopy and solid-state cross-polarization/magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CP/MAS ¹³C-NMR). The products recovered from OP can be applied in a wide array of fields, such as food, medicine, and pharmaceuticals, among others.