Determination of l-malate in wine by flow-injection with co-immobilized malate dehydrogenase/oxaloacetate decarboxylase.
A method for determination of l-malate in wine is described. Malate dehydrogenase and oxaloacetate decarboxylase were immobilized on poly (vinyl alcohol) beads and incorporated in a flow-injection system with fluorescence detection. Sample solution (50 mul) was injected into the carrier stream [4mM NAD(+) in glycine buffer (pH 10.0)]. The fluorescence based on the NADH formed could be directly related to the amount of malate. The calibration graph was linear over the range 0.4-300muM. The detection limit was 0.2muM. Sampling throughout was 25 samples/hr.
Kiba
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Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University, Kofu 400, Japan.
Oguchi
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Furusawa
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