Green extractions of soy waste (Glycine max (L.) Merr.)

Abstract

Soybeans are among the world's major crops responsible for food and biodiesel production. Around 460 million tons of soya by-products (branches, leaves, roots, and pods) were left into the field in the 2018/2019 harvest, and that 20-40% of this waste should be removed to ensure soil quality and minimize environmental impacts, such as climate change, water and soil contamination, and local air pollution. From a biorefinery concept, such residues might serve as a large available and cheap source of high-value-added metabolites, such as isoflavones, saponins, tocopherols, phenolic acids, and fatty acids. Only after such extractions, the final by-product would be addressed to low-added value applications, such as field fertilizers, animal feed or to the production of energy by combustion. In other words, these by-products should be valorized to create new value-added products, but at the same time to mitigate undesirable environmental impacts. From an environmental perspective, any waste valorization should be achieved throughout green technologies since there is no sense in converting agricultural by-products by employing polluting technologies, which would just increase the final amount of waste. This project aims to explore state-of-art green approaches to achieve high-value-added compounds rich extracts from soya by-products. For this purpose, soya by-products left onto the field after harvesting will be collected and extract using two-liquid-phases extractions, Pressurized Liquid Extraction (PLE), Microwave Assisted-Extraction (MAE) and Gas-expanded Liquids Extraction (GXLs). Bio-based solvents such as ethanol, d/l-limonene, and natural deep eutectic solvents (NADES) produced exclusively with food-compatible constituents will be tested as extraction media. The metabolic profiles of extracts will be obtained by UHPLC-ESI-Q-TOF-HRMS and GC-Q-TOF-HRMS. The extracts obtained will be tested for their potential antioxidant, anti-inflammatory and anti-neurodegenerative activities. All developments will be guided by the 12 principles of green analytical chemistry and will be compared side-by-side with prior art methods regarding extraction and environmental performances. (AU)