Efficient removal of water is essential for eventual quality product recovery as experience has shown that residual water will inhibit downstream crystallization and cause the SL product to take on the consistency of a sticky/gummy material that is difficult to work with rather than a white to off-white powder. After drying, the remaining yeast cells are separated from the SL product. In the model, this is accomplished through selective solublization in ethyl acetate.Sophorolipids are known to be soluble in ethyl acetate and so by washing the dried material from the fermenter in ethyl acetate, the SLs can be separated easily from the residual cellular material by filtration (ethyl acetate will also extract any unconsumed HOSO and OA; however, ourexperience has shown that, under the fermentation conditions employed, very-little-to-no residual hydrophobic carbon source remains). Once filtered, the ethyl acetate fraction goes through evaporation and a vacuum-drying process. As the ethyl acetate is removed, the SLs are concentrated and undergo crystallization into the final product. The cellular material is also dried using a drum dryer, and the ethyl acetate from both the SL stream (from the evaporator and vacuum dryer) and the cellular stream is recovered, passed through a molecular sieve dehydration unit and recycled for subsequent use. By recycling the ethyl acetate, cost-intensive processes such as higher solvent requirements and solvent disposal costs are avoided, helping to reduce overall production costs. Typically, smaller scale production processes use a final hexane precipitation step to further purify the SL products. In this model, the hexane step has been omitted due to the additional solvent handling problems associated with a costly, highly flammable solvent. Experience has shown that, although the SLs may not be as pure as when hexane is used, in the absence of water the simple concentration of the SLs from ethyl acetate will cause crystallization to occur, thus eliminating the need for hexane during industrial-scale production