Lecture 5. Natural Deep Eutectic Solvents in Extraction of Biologically Active Compounds

Abstract

The valorization of agricultural and fishery by-products by extracting their bioactive compounds is a very interesting alternative to their incineration or even composting. Bioactive compounds have been studied intensively due to their biological properties, capable of providing multiple health benefits. They can be extracted from by-products of agricultural, food, and fishing industries, such as crustaceans’ shells, plants, algae, or microalgae by-products, which can correctly contribute to a circular economy based on zero waste. For applications, mainly in the food, cosmetic and pharmaceutical industries, these compounds are generally extracted using organic solvents or also known as conventional solvents (methanol, acetone, benzene, chloroform, petroleum ether, and hexane), which many times are rejected for being flammable, explosive, poorly biodegradable and for the toxicity they can produce to the final consumer. Green technologies such as supercritical fluid extraction, ultrasonic extraction and microwave field extraction can increase process selectivity, increase productivity and increase efficiency, but they are costly and energy intensive. Alternative solvents, sometimes referred to as "green solvents", such as ionic liquid (IL) solvents, deep eutectic solvents (DES), and natural eutectic solvents (NADES) can be used as a solution to this problem [1]. In this review, developments related to the use of deep eutectic solvents for the extraction of different bioactive compounds and our own studies on ultrasound-assisted extraction of isoflavones of kudzu roots and flowers, red clover flowers and soy molasses as well as piperine from black pepper are briefly discussed.