Aqueous extraction processing: An innovative and sustainable approach for recovery of unconventional oils

Unconventional crops (e.g., tiger nut, macaw, babassu, sesame, and others) are promising edible oil sources. However, the traditional oil extraction methods, mechanical pressing, and solvent extraction show low efficiency or use environmentally unfriendly solvents (hexane). Aqueous extraction processing (AEP) has recently emerged as a significant opportunity for achieving the sustainable development goal (SDG) to produce edible oils. This technology usually requires a pre-treatment step, e. g., milling, followed by a demulsification step, which traditionally involves enzyme addition for free oil recovery. Optimizing the demulsification methods can lead to high oil yields (>95%), which is comparable to the use of hexane. This review discusses the scientific data and trends related to demulsification steps on AEP for oil recovery, focusing on unconventional oil crops. New physical demulsification possibilities, such as filter coalescers and membrane technology, are outlined as alternatives to traditional demulsification methods, which present some drawbacks regarding process scalability and oil quality. Additionally, a complete route, with a biorefinery approach, is suggested for the industrial application of oil and high-added-value compounds from the by-products of AEP (liquid and solid fractions) as an opportunity to update the traditional oil production sector. With the increased demand for conventional oils for biofuel purposes, exploring unconventional crops is a viable and suitable alternative to obtain food-grade oil. Integrating AEP with physical demulsification methods is an eco-friendly and promising strategy for producing high-quality oil from unconventional and minor crop sources since water is used as the solvent instead of hexane. Moreover, applying biorefinery concepts is an opportunity to stimulate the circular economy and produce valuable compounds (proteins, carbohydrates, fibers, and others) with beneficial health properties and wide application in food industries.