"The biosensor investigated was based on a thin layer enzyme cell in which glucose oxidase, invertase and mutarotase were immobilized on a protein membrane. Hydrogen peroxide as the product of the consecutive enzyme reaction was detected by amperometric technique. The optimum enzyme composition of invertase, mutarotase, and glucose oxidase for immobilisation was found to be 8498, 672, and 120U using 2.2mg BSA as protective agent dissolved in 200mu L phosphate buffer solution. To achieve the best measuring technique, changes in several parameters such as pH value, temperature and flow rate were studied. Having found the optimum conditions, the statistical parameters of the analysis were established. The linear range of the determination was between 1.0 x 10(-4) and 2.5 x 10(-3)mol/L with a correlation coefficient of 0.99. The sucrose content of several fruit juices was determined with this sensor, and the results were compared with an enzymatic reference method," wrote K. Majerbaranyi and colleagues.

The researchers concluded, "The correlation between the two sucrose determination methods was found to be 0.97."

Majerbaranyi and colleagues published their study in European Food Research and Technology (Investigation of a multienzyme based amperometric biosensor for determination of sucrose in fruit juices. European Food Research and Technology, 2008;228(1):139-144).

Additional information can be obtained by contacting K. Majerbaranyi, Cent. Food Research Institute, Herman Otto Ut 15, H-1022 Budapest, Hungary.

From the December 5, 2008, Prepared Foods e-Flash