Improved synthesis of sophorolipid biosurfactants using industrial by-products and their practical application

Abstract

Abstract Surfactants are amphipathic molecules that are generally chemically derived. Compared to these surfactants, biosurfactants have a better environmental profile and are derived from microorganisms. Among the biosurfactants, sophorolipids (SLs) are probably the most promising biosurfactants. In general, the costs of raw materials in the synthesis of biosurfactants accounts for about 10–30% of the total costs. These costs can be reduced to some extent by using industrial by-products as substrates for the synthesis of SLs. In this study, sunflower acid oil (SAO), a by-product of sunflower oil refining, and crude glycerol (so-called “sweetwater”), which is the glycerol-rich solution from the mixed fat hydrolysis reaction, also an industrial by-product, are used for the synthesis of SLs. We obtained comparable yields (0.8/50 mL) to previous reports using a combination of treated SAO (10% w/v) and sweetwater (19% w/v). For the bleaching process, we used 1% and 3% activated earth for normal and heavy treatments over a period of 1 h and 3 h, respectively. Glycerol is inexpensively available in the form of sweetwater from fat-splitting plants and was used as the hydrophilic source. The purification of the SL can be achieved by crystallization at pH 7. The purified SL is analyzed by thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FTIR), and high performance liquid chromatography (HPLC). Then, it was incorporated into different liposomal formulations for the encapsulation of the non-steroidal anti-inflammatory drug (NSAID) ibuprofen. The ratio of drug to cholesterol and SL was 1:1:0.5. The liposomal structures were examined for their size of 2 µ by direct light scattering.