Production of Biodiesel and Protein Isolates from Dehulled Yellow Mustard Flour

Aqueous extraction is an emerging alternative to hexane-based oilseed extraction since it eliminates the dangers associated with processing, and allows the simultaneous recovery of high-quality protein products and vegetable oils. Five different non-enzymatic and enzymatic aqueous extraction processes (AEP/EAEP) were developed for dehulled yellow mustard flour with the aim of producing food-grade protein isolates and fuel-grade biodiesel. The oil released in these processes was tied up in oil-in-water emulsions that must be destabilized to recover free oil prior to biodiesel production. The remarkable stability of the released emulsion was due to the presence of protein emulsifiers of high molecular weight along with the mixed phospholipid-oleosin layer. pH adjustment and enzymatic treatments with different proteases and phospholipases for emulsion destabilization were relatively inefficient; therefore, a novel chemical approach was developed based on dissolution of the emulsion in tetrahydrofuran (THF) or dioxane to recover the released oil in the form of single-phase oil-solvent-water miscella suitable for direct conversion to biodiesel through single-phase base-catalyzed transmethylation after reducing the water content to the quality standards required for biodiesel feedstock. The emulsion destabilization using organic solvents was optimized, based on experimentally prepared ternary phase diagrams of THF/oil/water and dioxane/oil/water, and the results suggest that this technically viable approach can successfully recover essentially all of the oil from the emulsion. The resulting miscella phases were successfully dehydrated by adsorption over zeolite 4A using either batch or fixed-bed systems. The dehydrated miscella phases were finally reacted with methanol in a single-phase transmethylation process with high yields (99.3 wt%) to fatty acid methyl esters (FAME). The resulting FAME satisfied the international standards for use as biodiesel fuel. Finally, our integrated process consisting of aqueous contact of mustard flour to recover protein as the main product followed by dissolution of the resulting emulsion with THF could produce high-quality protein products free of solvent contact/residues, while biodiesel could be efficiently recovered using a less flammable solvent than conventional hexane extraction. We believe that this study will help Canada to balance food and biofuel production that can lead to lower food prices, benefiting many poor people in the world.Ph.D.2017-06-30 00:00:0