University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Food -> cheese -> cottage

Citations 1

"Amperometric Bi-enzyme Based Biosensor For The Detection Of Lactose - Characterization And Application"
J. Chem. Technol. Biotechnol. 1990 Volume 49, Issue 3 Pages 255-265
Dorothea Pfeiffer, Edmundas V. Ralis, Alexander Makower, Frieder W. Scheller

Abstract: A 50 µL portion of 5% gelatin solution was mixed with β-galactosidase (I) from Escherichia coli (10.0 iu), Bifidobacterium adolescentes (4.0 iu) and Curvularia inaequalis (10.0 iu) and spread on 1 cm2 of polyethylene support (cf. Scheller et al., DD Patent 150 500, 1979). Additionally, cross-linking using polyvinylisocyanate (40 mL of 5% solution cm-2) was used (cf. Nentwig et al. DD Patent 277 888 4, 1985). The bi-enzyme membrane, obtained by combining a commercial glucose oxidase layer with a I layer between two cellulose membranes, was used to cover Clark-type electrodes which were then used manually or in a continuous-flow system at +600 mV vs. Ag - AgCl. The electrode was used to determine lactose (II) in milk, whey, baby foods, cottage cheese and bovine urine. The calibration graph was rectilinear for 25 mM II; the detection limit was 20 µM. In the analysis of milk, the coefficient of variation (n = 20) was 2%. Results compared well with those obtained by IR spectroscopy and photometry.
Lactose Amperometry Electrode Sensor Enzyme Membrane Calibration Detection limit Method comparison