The isolation of hydroxy acids from lesquerella oil lipolysate by a saponification/extraction technique

The lipolysate from immobilized Rhizomucor miehei lipase (Lipozyme(TM))-catalyzed hydrolysis of lesquerella oil contains typically 35% free fatty acid (FFA), 2% monoglyceride, 25% diglyceride (DC), and 38% triglyceride (TC). Of the FFA, 75-80% are hydroxy acids (HFA). Various methods for isolating HFA from the lipolysate were examined, and a novel saponification/extraction method was developed. Lipolysate was mixed with 4 vol equivalents each of KOH/phosphate buffer and polar organic solvent. Hexane was then added to enhance phase separation. Three phases formed: a lower aqueous phase containing nothing of interest, a polar organic solvent middle phase that contained mostly fatty acid soaps, and a hexane-rich upper phase that contained mostly DG and TC, which can be recycled to a relipolysis step. The middle phase, when treated with concentrated hydrochloric acid, NaCl-saturated water, and hexane, released the FFA into the hexane. This fraction, referred to as the ''Product,'' contained >99% of the FFA released in the lipolysis. ''Product'' consisted of 85-90% FFA, of which 75-80% was HFA. The other 10-15% of the ''Product'' consisted of partial glycerides and TG. The most critical parameters for the extraction are the pH of the aqueous solution and the polarity of the organic solvent (acetone was found to be the best choice). Additional purification steps for the ''Product'' are discussed.