Determination of total cholesterol content in food by flow injection analysis with immobilized cholesterol oxidase enzyme reactor.

A new analytical method has been developed--including a new sample preparation procedure--for the automatic determination of total (free and bound) cholesterol in food by flow injection analysis (FIA) with immobilized (cholesterol oxidase) enzyme reactor (IMMER). A suitable sample preparation procedure has been applied to eliminate the problems derived from sensitivity of FIA equipment to common organic solvents used for dissolving of cholesterol: after direct saponification the non-saponificable fraction was dissolved in water phase detergent (sodium cholate) solution. The analytical method is based on the oxidation by cholesterol oxidase followed by the photometric determination of hydrogen peroxide (at 500 nm) using the indicator reaction with peroxidase. The new FIA method was tested for commercial food samples such as whole egg powder and dried pasta. The results were compared with data obtained by GC-determination. It was found that this new procedure is suitable for rapid automated measurement of total cholesterol content in foodstuff and consequently, the FIA technique with immobilized enzyme reactor could be an alternative to the widely used gas-chromatographic (GC) method.