MPEROMETRIC BIOSENSOR FOR GLUCOSE DETERMINATION IN APPLE JUICE. ANALYSIS OF INTERFERENCES

RISTOFF, M. E.; SORRIVAS, V.; SAIDMAN, S.; LOZANO J. E.

ANTALYA

Congreso; 1ST INTERNAT. CONGRESS ON FOOD TECHNOL.; 2010

Research on amperometric biosensors attracts lots of current interest because of their potential applications in the food industry. The objective of the present work was (i) to determine possible interferences of electro-active compounds found in apple juice; and (ii), when the interference was identified, eliminate or reduce it by the appropriate method. Carbon paste biosensors were prepared by hand-mixing glucose oxidase, graphite powder, paraffin, and ferrocene as mediator. Assay conditions were pH, 7; enzyme content, 10%; and applied voltage, 0.16V. Optimal working conditions were determined. The dispersion of enzyme in graphite was characterized using scanning electron microscopy (SEM, JEOL 6300F). The scanning electron microscopic (SEM) images were taken of the graphite surface before and after immobilization. Solutions of fructose, malic acid, sucrose, starch and ascorbic acid where added to the assayed buffer solution up to a concentration currently found in apple juice. Results indicate that the addition of fructose, malic acid, sucrose and starch do not interfere under these working conditions. Contrarily, ascorbic acid is a major interferent at the chosen potential. The reduction of ascorbic acid was performed enzymatically by ascorbate oxidase, previous to glucose determination.