FIA-SYSTEMS FOR THE DETERMINATION OF MALTOSE, LACTATE AND VOLATILE SUBSTANCES IN BEER, WINE AND FERMENTATION BROTHS

Abstract

FIA-systems with immobilized enzymes for analysis of substrates in biological matrices are described. Direct or coupled reactions lead to the commonproduct NADH, which is determined byfluorimetry. The flow systems imply modulesfor the purification, dilution and pH adjustment of the samples. A system is presented for the determinationof volatile substrates using pervaporation as sample purification. Applications for the quantification of ethanol in beer (measurable range 0.5 - 20 mM) and acetaldehyde in wine (measurable range 0.01 - 0.05 mM) are given. By automated switching of the analyte between parallel assembled dehydrogenase columnsthe control of ethanol (calibration range 0.03 -10 mM) and lactate (calibration range 0.01 - 10 mM)in a fermentation of Clostridium thermohydrosulfuricum is possible. The determinations show goodreproducibility and Satisfactory agreement with results of a common enzymatic test-kit. A more sophisticated experimental setup including ion exchange and dialysis as purification steps is developedfor cyclic/parallel determination of glucose, maltose(linear range 0.3 - 15 mM for both sugars) and ethanol(linear range 6 - 500 mM)in beer. Process stability of the enzymes proved to be Satisfying.