Abstract: Flow injection fluorimetric analysis systems incorporating enzyme reactors are described. The first system, for determination of glucose (I) and ethanol in baker's yeast fermentations, contains a microfiltration module (described) for exclusion of micro-organisms, a glucose dehydrogenase reactor and an alcohol dehydrogenase reactor. The second system, for determination of I and sucrose in fruit juice and lemonade, contains three β-fructosidase reactors in series, a mutarotase reactor and a glucose dehydrogenase reactor. The third system, for determination of I and pullulan contains an α-dextrin endo-1,6-α-glucosidase reactor, an amylglycosidase reactor and a glucose dehydrogenase reactor. All systems require NAD+ in the carrier stream.

Abstract: Pullulan (I) and glucose (II) are determined in filtered Aureobasidium pullulans fermentation broth after hydrolysis with α-dextrin endo-1,6-α-glucosidase and glucan 1,4-α-glucosidase immobilized on controlled-pore glass. Total II (i.e., that formed by hydrolysis and that present as such in the initial sample) is determined in a FIAstar 5020 analyzer. by oxidation with glucose 1-dehydrogenase in the presence of NAD+ and spectrophotometric monitoring of the NADH formed. Free II was determined similarly without enzymatic hydrolysis, and the I content was calculated by difference. The calibration graphs for both I and II were rectilinear over the range 2 to 20 mg l-1. One analysis takes only 10 min and the system response remains constant for 30 samples. A flow injection system is described for the parallel determination of pullulan and glucose during a fermentation of the fungus Aureobasidium pullulans. The polysaccharide was hydrolyzed by pullulanase and amyloglucosidase immobilized to controlled-pore glass. The glucose produced was oxidized by glucose dehydrogenase, and the NADH formed was determined photometrically. The pullulan concentration. was calculated from the difference to the response obtained for free glucose. The calibration curves for monomer and polymer were both linear between 2 and 20 mg/L. The determination of glucose and pullulan took ~10 min per sample.