Abstract
Onion is consumed globally in several forms and has been recognized as a source of minerals, essential oils, and proteins. It is mostly used in food preparations to enhance the organoleptic quality of cooked foods. While processing onions, a large amount of waste, mostly in the form of peels, fleshy scales, roots, bulbs, etc., are left behind, which are rich sources of bioactive compounds that can be extracted through suitable technologies for the development of value-added products. Onion waste can also be fermented for the production of bioethanol and, therefore, holds great value to the industrial bioprocessing sector. This chapter discusses various innovative, contemporary valorization approaches (chemical, thermal, enzymatic, and biotechnological, etc.) for the extraction of functional components from onion waste and the production of value-added products from them for sustainable growth through the circular economy mode.