Crucial Challenges in the Development of Green Extraction Technologies to Obtain Antioxidant Bioactive Compounds from Agro-industrial By–Products

K. A. Gil and C. I. G. Tuberoso

Abstract
Exploitation of agro-industrial by-products represents an important source of bioactive compounds that can be used both directly as ingredients and for the production of functional ingredients. Among these compounds, polyphenols are capable of strengthening endogenous antioxidant defences in human tissues, preventing cardiovascular and neurodegenerative diseases. The present paper aims to evaluate and review various green extraction technologies for a cheap, fast, eco-friendly procedure to obtain these bioactive molecules. Several physicochemical approaches can be used with the aim of optimizing the use of energy, solvents, and pressure; among them are ultrasound-assisted extraction, subcritical and supercritical fluid extraction, extraction with neoteric solvents (ionic liquids, deep eutectic solvents, and natural deep eutectic solvents), microwave-assisted extraction, pressurized liquid extraction, pulsed electric field, multi-frequency multimode modulated technology, rapid solid liquid dynamic extraction, and enzyme-assisted extraction. The challenges and future work regarding the development of these green products for the commercial markets were comprehensively evaluated.

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Keywords
agro-industrial by-products, green extraction technologies, antioxidant activity, bioactive compounds, polyphenols, food industry