Extraction of Valuable Compounds from Leaf Vegetables By-Products

Leafy vegetables represent the agricultural crops with highest use. These vegetables are usually consumed raw, or submitted to mild processing, to preserve their health-promoting properties. In either case, consumers are highly receptive to these, particularly due to the association among their consumption and an improved health status, which has been impacting the overall horticultural sector to reach progressively higher production levels to satisfy those expanding requests. Despite the potentially beneficial economic effects of this evolution, the generation of alarming quantities of by-products and wastes is a serious drawback. Actually, the United Nations Food and Agriculture Organization identified fruits and vegetables as the products that generate the highest level (around 60%) of losses and wastes. A considerable part of this loss is originated throughout the industrial processing of these products, from which a complex mixture of barks, husks, skins, seeds, and leftover flesh is generally obtained. This residual material (pomace) has high quantities of different bioactive and functional phytochemicals, often in higher concentrations than the fresh products themselves. Surprisingly, this high-potential material is usually discarded, reducing the possibility of obtaining high-value compounds that could be used as unique ingredients in food or pharmaceutical-related applications. In some occasions, the overall process is not well succeeded due to the lack of a suitable extraction technology. Accordingly, different extraction technologies will be analyzed and compared to validate their effective significance in by-products valorization.