Low-cholesterol milk production using cholesterol oxidase from Nocardia erythropolis

An effective process for reducing milk cholesterol by enzymatic treatment was investigated in this study. Cholesterol oxidase from Nocardia erythropolis was used for this purpose. The target of this investigation was to obtain the optimum operational conditions for bioconversion of milk cholesterol by cholesterol oxidase (COD). The bioconversion process was investigated first, to obtain basic information about the process, and was further optimised by analysing the parameters, including temperature, pH, incubation time and enzyme content, by using the Taguchi Approach, which is a statistical method for optimisation. Also the direct effect of each parameter on cholesterol bioconversion rate has been studied. As a result, the suitable operational conditions were obtained: temperature 32 C, pH 7.5, incubation time of 120 min and enzyme content in milk 0.15 U/mL, which under these conditions, approximately 70% of milk cholesterol was removed. Aust. J. Dairy Technol. 65, 10-14