Application of response surface design to solvent, temperature and lipase selection for optimal monoglyceride production

This work focuses on the use of a temperature and solvent lipase stability procedure as a practical approach for selection of the most favorable conditions for the enzyme catalysis production of mono-glycerides from glycerin and triolein. Two lipases were selected for analysis: a lipase from Candida rugosa immobilized on chitosan and a lipase from Mucor miehei immobilized on a macroporous anionic exchange resin of the phenolic type. Using a 3(2) factorial experimental design, the effects of temperature within the range of 35-45 degrees C and solvent ratios of acetone:isooctane between 0.25:0.75 and 0.75:0.25 (v/v) were evaluated on the activity of the lipase. Lipase from M. miehei revealed a higher residual activity (91%) following a 24 h incubation with the solvent acetone:isooctane at a ratio of 0.25:0.75 (v/v) at 35 degrees C while C. rugosa lipase reached a maximum residual activity of approximately 56% after a 24h incubation with a solvent acetone:isooctane ratio of 0.25:0.75 (v/v) between 35 and 42 degrees C. For the M. miehei lipase, these results were evaluated experimentally by testing glycerolysis of triolein (biocatalyst initial water activity (a(w)) 0.534, molar ratio glycerin:triolein 3:1, amount of protein 90 mg, 24 h). Using the best (35 degrees C, 0.75 Ac) and the worst (45 degrees C, 0.75 Ac) conditions for residual activity in stability assays, it was confirmed that when the predicted optimum conditions were applied, a monoolein yield of over 68% and a total conversion of triolein of approximately 89% were reached. (C) 2011 Elsevier B.V. All rights reserved.