Utilization of two microbial lipases in free and immobilized forms for hydrolysis of butteroil emulsions

The present research describes results obtained from the enzymatic hydrolysis of butteroil emulsions by lipases. As a necessary analytical tool, a HPLC method for determination of free fatty acids in butteroil was developed. Free (soluble) A. niger lipase preferentially hydrolyzes flavor-rich short-chain fatty acids (particularly butyric acid) at pH 5. The rates of hydrolysis of medium and long chain fatty acids and the overall rate of hydrolysis were fastest at pH values between 6 and 7. The possibility of directing the selectivity of the lipolysis of milkfat towards the short chain fatty acids is discussed.; Immobilization of the same lipase on microporous polypropylene was also studied. Langmuir isotherms can be employed to characterize the adsorption of both total protein and lipolytic acitivity on this hydrophobic polymeric membrane. A model was developed to describe the selective adsorption of the lipase relative to other proteins present in the crude preparation.; Lipase from C. rugosa was also immobilized by hydrophobic adsorption on a polypropylene membrane. This membrane was then employed to fabricate an axial-annular flow reactor. Rate expressions based on postulated reaction mechanisms were developed for use in modelling the performance of the reactor. Nonlinear fits of the experimental data were consistent with a mechanism which assumes that deacylation of the enzyme is the rate limiting step in the hydrolysis reaction. Relatively high rates were observed for the overall hydrolysis reaction. Free fatty acid concentrations of 2.35 mmol/ml could be achieved at a reactor space time of 6 hours.; Analysis of the free fatty acids profiles of the hydrolyzed effluent from the axial annular flow reactor and commercial samples of lipolyzed butteroil (LBO) indicated that only short space times (ca. 20 minutes) are needed to reach levels of free short chain fatty acids similar to those contained in commercial LBO.; A preliminary economic assessment of the commercial potential of a large scale axial annular flow reactor indicates that the use of the immobilized enzyme technology can lead to significant savings. This benefit should encourage current producers of LBO to upgrade their technology by adopting the use of immobilized lipase reactors.