Immobilized enzyme technology for the production of milkfat enriched in conjugated lineoleic acid

An expanding body of results obtained in studies of animal models indicates that incorporation of conjugated linoleic acid (CLA) in the diet confers a number of health benefits. Two steps in a process for producing modified milkfats enriched in CLA residues are hydrolysis of corn oil and direct acidolysis of milkfat with free CLA. The research described in this dissertation focuses on the kinetics of these reactions.; The kinetics of the hydrolysis of corn oil in the presence of a lipase from Pseudomonas sp. immobilized in a hollow fiber reactor can be modeled in terms of a three-parameter rate expression. This rate expression consists of the product of a two parameter rate expression of the generalized Michaelis-Menten form for the hydrolysis reaction and a first-order rate expression for deactivation of the enzyme. Under optimum operating conditions (30°C and a buffer pH of 7.0), the total free fatty acid concentration in the effluent stream for a pseudo space time of 4 hours was approximately 1.55 M. This concentration corresponds to hydrolysis of approximately 47% of the glyceride bonds present in the corn oil feedstock.; Concentrations of the five different free fatty acids in the effluent stream were measured using HPLC to assess the selectivity of the enzyme-mediated hydrolysis reaction. A multiresponse nonlinear regression analysis was employed to determine the kinetic parameters of the rate expression associated with a generic ping-pong bi-bi mechanism. At quasi-optimum operating conditions, the effluent concentration of free linoleic acid (C18:2), the fatty acid of primary interest, was approximately 0.53 M for a pseudo space time of 8 hours.; Acidolysis of butteroil with free CLA was studied in a packed bed reactor containing immobilized Candida antarctica (fraction B). At temperatures from 45–55°C and a 10:1 (w/w) ratio of butteroil to CLA, relatively short pseudo space times (less than three hours) were sufficient to obtain an effluent containing a significant proportion of CLA residues (60–85% of the original free CLA). At 50°C, similar levels of incorporation of CLA (60–85%) were achieved at low space times for both 10:1 and 2:1 (w/w) ratios of butteroil to CLA.