para-Menthane as a Stable Terpene Derived from Orange By-Products as a Novel Solvent for Green Extraction and Solubilization of Natural Substances

Leading Edge Technologies and Perspectives in Industrial Oilseed Extraction

With the increase in the world's population and per capita wealth, oil producers must not only increase edible oil production but also meet the demand for a higher quality and variety of products. Recently, the focus has shifted from single processing steps to the entire vegetable oil production process, with an emphasis on introducing innovative technologies to improve quality and production efficiency. In this review, conventional methods of oilseed storage, processing and extraction are presented, as well as innovative processing and extraction techniques. Furthermore, the parameters most affecting the products' yields and quality at the industrial level are critically described. The extensive use of hexane for the extraction of most vegetable oils is undoubtedly the main concern of the whole production process in terms of health, safety and environmental issues. Therefore, special attention is paid to environmentally friendly solvents such as ethanol, supercritical CO2, 2-methyloxolane, water enzymatic extraction, etc. The state of the art in the use of green solvents is described and an objective assessment of their potential for more sustainable industrial processes is proposed.

Sustainable recovery of phenolic antioxidants from real olive vegetation water with natural hydrophobic eutectic solvents and terpenoids

Olive oil production leads to the generation of olive mill wastewater (OMWW). Due to the presence of phenolic compounds, they are difficult to process, but they represent a source of high-added value chemicals since they have antioxidant and therapeutic properties. This work has studied the extraction of phenolic compounds from a type of OMWW, olive vegetation water, which presents these compounds in a more diluted dosage than in other studied to date, to revalue this waste stream. A real olive vegetation water from a Spanish olive oil producer was used, and liquid-liquid extraction was applied. Terpenoids and terpene-based hydrophobic eutectic solvents were systematically used to extract phenolic compounds following the concentrations of tyrosol, catechol, caffeic acid, and total phenolic content. By molecular simulation with the COSMO-RS method, 4 terpenoids, and 2 eutectic solvents were selected and compared with 2 conventional solvents. The Solvent/Feed ratio in the extraction of phenolic compounds was studied, showing that the solvents with the highest extraction results were geraniol, eucalyptol, and eutectic solvent menthol + camphor, which outperformed conventional solvents methyl isobutyl ketone and diisopropyl ether. Menthol + camphor gave total phenol extraction yields of 88.73% at a Solvent/Feed ratio in volume of 0.50, surpassing all solvents tested. A solvent reuse and regeneration process was applied by back-extraction of the 4 solvents: FTIR results showed the stability of the solvents while maintaining yields in the solvent reuse process. The phenolic compounds could be concentrated in the alkaline phase to factors up to 49.3 to the initial concentration in olive vegetation water. The alkaline phases were neutralized to obtain a precipitate with a caffeic acid content of up to 26 % wt%, and a tyrosol-rich supernatant with a concentration of up to 6.54 g/L. This work proposes a process using natural solvents to extract phenolic compounds from olive vegetation water.

Bio-Refinery of Oilseeds: Oil Extraction, Secondary Metabolites Separation towards Protein Meal Valorisation—A Review

Edible oil extraction is a large and well-developed sector based on solvent assisted extraction using volatile organic compounds such as hexane. The extraction of oil from oilseeds generates large volumes of oilseed by-products rich in proteins, fibres, minerals and secondary metabolites that can be valued. This work reviews the current status and the bio-macro-composition of oilseeds, namely soybean, rapeseed, sunflower and flaxseed, and the refining process, comprising the extraction of oil, the valorisation and separation of valuable secondary metabolites such as phenolic compounds, and the removal of anti-nutritional factors such as glucosinolates, while retaining the protein in the oilseed meal. It also provides an overview of alternative solvents and some of the unconventional processes used as a replacement to the conventional extraction of edible oil, as well as the solvents used for the extraction of secondary metabolites and anti-nutritional factors. These biologically active compounds, including oils, are primordial raw materials for several industries such as food, pharmaceutical or cosmetics.

A Review of the Use of Eutectic Solvents, Terpenes and Terpenoids in Liquid–liquid Extraction Processes

Diverse and abundant applications of the eutectic solvents have appeared in the last years. Their promising tunable properties, eco-friendly character and the possibility of being prepared from numerous compounds have led to the publication of numerous papers addressing their use in different areas. Terpenes and terpenoids have been employed in the formulation of eutectic solvents, though they also have been applied as solvents in extraction processes. For their hydrophobic nature, renewable character, low environmental impact, cost and being non-hazardous, they have also been proposed as possible substitutes of conventional solvents in the separation of organic compounds from aqueous streams, similarly to hydrophobic eutectic solvents. The present work reviews the application of eutectic solvents in liquid–liquid extraction and terpenes and terpenoids in extraction processes. It has been made a research in the current state-of-the-art in these fields, describing the proposed applications of the solvents. It has been highlighted the scale-up feasibility, solvent regeneration and reuse procedures and the comparison of the performance of eutectic solvents, terpenes and terpenoids in extraction with conventional organic solvents or ionic liquids. Ultimately, it has been also discussed the employ of predictive methods in extraction, the reliability of thermodynamic models in correlation of liquid–liquid equilibria and simulation of liquid–liquid extraction processes.