Deep eutectic solvents as an alternative for extraction of flavonoids from soybean (Glycine max (L) Merrill) and okara: An experimental and computational approach based on COSMO-SAC model.

In this study, different Deep Eutectic Solvents based on choline chloride ([Ch]Cl) with carboxylic acids, sugars, and glycerol, were investigated as alternative solvents for the extraction of flavonoids from soybean and okara. Initially, the COSMO-SAC was investigated as a tool in solvent screening for the extraction of flavonoids. Experimental validation was performed using total flavonoid analysis with the solvents that showed greater interaction with the solutes. The extracts obtained from soybean and okara using the DES [Ch]Cl:acetic acid added with 30 % water showed the highest total flavonoid content, 1.05 mg eq. of catechin/g dry soybean and 0.94 mg eq. of catechin /g dry okara, respectively. For phenolic compound extraction, [Ch]Cl: acetic acid DES extracted approximately 1.16 mg GAE/g of soybean and 0.69 mg GAE/g of okara. For antioxidant activity, soybean and okara extracts obtained with [Ch]Cl: acetic acid showed FRAP results of 0.40 mg Trolox/mL of extract and 0.45 mg Trolox/mL of extract, respectively. In addition, the isoflavones daidzein, genistein, glycitein, daidzin, genistin, and glycitin were identified and quantified in the soybean and okara extracts obtained with DES [Ch]Cl: acetic acid with 30% water, totaling 1068.05 and 424.32 µg total isoflavones/g dry sample. Therefore, The COSMO-SAC model was a useful tool in solvent screening, saving time and costs. Also, DES can be an alternative solvent for extracting flavonoids to replace conventional organic solvents, respecting current environmental and human health concerns.

Solid-liquid equilibria of triacylglycerols and vitamin E mixtures.

Oils and fats are important ingredients for food and pharmaceutical industries. Their main compounds, such as triacylglycerols (TAG), are responsible for determining their physical properties during food storage and consumption. Lipid-rich foods are also sources of minority compounds, which is the case of vitamin E, mainly represented by (±)-α-tocopherol. These compounds can interact with the main lipid molecules in food formulation leading to modification on lipids' physicochemical properties during processes, storage, as well as during digestion, possibly altering their nutritional functionalities, which is the case of vitamin E antioxidant abilities, but also their solubility in the systems. In this case, the study of the phase-behavior between (±)-α-tocopherol and lipid compounds can elucidate these physicochemical changings. Therefore, this work was aimed at determining the solid-liquid equilibrium (SLE) of binary mixtures of TAG (tripalmitin, triolein and tristearin) and (±)-α-tocopherol including the complete description of their phase diagrams. Melting data were evaluated by Differential Scanning Calorimetry, Microscopy, X-Ray Diffraction, and thermodynamic modeling by using Margules, UNIFAC, and COSMO-SAC models. Experimental results showed that systems presented a monotectic-like behavior, with a significant decreasing in TAG melting temperature by the addition of (±)-α-tocopherol. This high affinity and attractive strengths between these molecules were also observed by thermodynamic modeling, whose absolute deviations were below 2 %. Micrographs and X-ray diffraction evidenced the possible formation of solid solutions. Both behaviors are interesting by avoiding phase separation on food in solid and liquid phases, possibly improving the antioxidant role the (±)-α-tocopherol in lipid-base systems.