Subcritical and Supercritical Extraction in Food By-product and Food Waste Valorization

Abstract Last years of the 20th century were marked with increased industrial and scientific interests of agricultural and food-processing waste and by-products as well as with worldwide interest in natural dietary products, functional food and natural cosmetics. Available literature indicates that food waste may represent low-cost source of wide range of valuable compounds, such as polyphenols, carotenoids, pigments, carbohydrates, proteins and amino acids, oils and fatty acids, with prospective for application in pharmaceutical, food and cosmetic industries. Accordingly, a growing area of research in the development of green technologies is devoted to designing new extraction techniques for food waste valorization that comply with strict environmental requirements. Two innovative extraction techniques that use environmentally-friendly, non-toxic and tunable solvents which could meet the technological and economic demands of individual process are subcritical and supercritical fluid extraction. In contrast to conventional alternatives, these extraction techniques require lower amounts of organic solvents and shorter extraction time giving better yields and selective extracts. Therefore, this chapter aims to present an update perspective on the subcritical and supercritical extraction together with the most notable applications for the extraction of valuable compounds from food waste and by-products.