Hydrolysis of butteroil by immobilized lipase using a hollow‐fiber reactor: part II. Uniresponse kinetic studies

A lipase from Aspergillus niger immobilized by adsorption on microporous, polypropylene hollow fibers was used to effect the hydrolysis of the glycerides of melted butterfat at 40°C and pH 7.0. Mcllvane buffer was pumped through the lumen and melted butterfat was pumped courrently through the shell side of a shell‐and‐tube reactor. Nonlinear regression methods were employed to determine the kinetic parameters of three nested rate expressions derived from a Ping Pong Bi Bi enzymatic mechanism coupled with three nested rate expressions for the thermal deactivation of the enzyme. For the reaction conditions used in this research, a four‐parameter rate expression (which includes a two‐parameter deactivation rate expression and a two‐parameter hydrolysis rate expression) is sufficient to model the overall release of free fatty acids from the triglycerides of butterfat as a function of space time and time elapsed after immobilization. At a space time of 3.7 h immediately after immobilization of lipase, 50% of the fatty acid residues esterified in the sn‐1,3 positions of the triglycerides can be released in the hollow‐fiber reactor.