Enzymic determination of glucose in foodstuffs (original) (raw)
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Enzyme Based Self-Prepared Kit to Measure the Glucose Concentration in Comparison with Standard Kit
In the present study, glucose oxidase was produced in shake culture by the parent Aspergillus niger with corn steep liquor as substrate. Glucose oxidase produced was then purified by subjecting to 60-85% saturation of ammonium sulfate precipitation and further purified by ion exchange and gel filtration chromatography respectively. Desalted sample of glucose oxidase showed the activity and specific activity of 39.19 U/ml and 9.07 U/mg. For ion exchange chromatography, 8 fraction of glucose oxidase had the maximum th activity of 19.99 U/ml with 17.70 U/mg specific activities. Gel filtration chromatography was applied by sephadex G-200 and glucose oxidase showed a specific activity of 54.243 U/mg. Peroxidase from horseradish obtained activity and specific activity of 21.78 U/ml and 9.64 U/mg, respectively after ammonium sulfate precipitation. DEAE-cellulose chromatography of peroxidase showed activity of 10.36 U/ml and specific activity 57.88 U/mg that was 5.07 U/ml and 66.71 U/mg aft...
Enzyme electrodes for the determination of carbohydrates in food
Sensors and Actuators B: Chemical, 1993
Characteristic features of screen-printed enzyme electrodes for glucose, lactose and sucrose are described. Glucose oxidase was immobilized on a screen-printed Pt electrode either by crosslinking with glutaraldehyde or by adsorption in an enzyme paste which incorporated either platinized graphite or graphite modified with the mediator tetrathiafulvalene. Thus, detection was based on either H,O, oxidation or mediator oxidation. The highest reproducibility was obtained with sensors based on the enzyme crosslinked with glutaraldehyde. Hence, this immobilization procedure was also used for the preparation of lactose and sucrose sensors. These sensors are based on co-immobilized j-galactosidase and glucose ox&se and invertase, mutarotase and glucose oxidase, respectively. Adding mutarotase to the enzyme mixture of the sucrose sensor enhanced sensitivity approximately 100 times. The linear range of the sensors could be increased by additional membranes fixed over the electrode surface. The greatest effect was observed using membranes with a reduced number of pores. This also led to a decrease in the sensitivity of the sensor. Additionally, these sensors showed a reduced response to ascorbic acid, the main electrochemically interfering compound in food. Hence, no interference was observed in juices without added ascorbic acid.
Journal of Pharmacological and Toxicological Methods, 2000
In experimental models of diabetes, glucose levels in plasma and blood are commonly determined by colorimetric assay and by automated analyzers based on the glucose oxidase conversion of glucose and O 2 to gluconate and H 2 O 2. We have compared the glucose levels obtained by these two methods in control Wistar rats, streptozotocin diabetic Wistar rats, Zucker fa/fa fatty rats and Zucker Diabetic Fatty rats. We found that the manual glucose assay and the glucose analyzer produced comparable values up to concentrations of about 25 mM. Above this level, samples should be diluted.
The Analyst, 2001
All ATP coupled reactions, when performed at neutral or moderately alkaline pH, produce an acidification of the reaction mixture. The detection of small pH changes -0.1 mpH (1 mpH = 10 23 pH)-in a constant buffering capacity solution makes it possible to quantify, over a wide concentration range (1-1500 mmol L 21 ), various analytes with very high precision and accuracy. Glucose, fructose, glycerol and gluconic acid can be analysed in less than 1 min with a single step reaction. Wine samples were analysed using the hexokinase reaction for glucose + fructose (sugars undergoing fermentation) and compared against an established method, showing excellent performance over the whole range of concentrations (R = 0.9994). Increased sensitivity in some applications can be obtained by cycling reactions, e.g. a kinase reaction followed by a phosphatase reaction, in a one step analysis, as required for lactulose assay in milk, a useful indicator of heat treatment damage. A sensitivity well below 0.1 mmol L 21 in the original milk sample has been demonstrated.
Food Chemistry, 2011
An amperometric biosensor based on a ruthenium(III), nickel(II) and iron(II) hexacyanometallate (HCM)modified graphite electrode and immobilized glucose oxidase has been used for the determination of glucose in water-miscible organic solvent/aqueous buffer mixtures. Although the specific activity of biochemically active molecule such as enzyme is reduced in organic environment, it was established that the presence of water soluble organic solvents such as methanol, ethanol and acetonitrile (u = 10%) enhance the biosensor response. Hydrogen peroxide, produced by enzyme-catalysed reduction of glucose, was measured in phosphate buffer solution (pH = 6.86) at À50 mV against a reference Hg|Hg 2 Cl 2 |3 M KCl electrode to determine the concentration of glucose. The influence of the addition of different volume fractions (u = 10-60%) of methanol, ethanol, acetone, acetonitrile and isopropanol on biosensor response was investigated. The obtained amperometric signals were fast, reproducible and linearly proportional to glucose concentrations in the range of 0.1-0.8 mM, with a squared correlation coefficient of 0.9994 for buffer solution. With the addition of ethanol (u = 10% and 40%) the plateau on I/c curve was obtained for concentrations of glucose higher than 0.8 and 1.1 mM, respectively. The biosensor proved to be stable for several months. The recoveries of added glucose (0.200 and 0.300 mM) from aqueous solution and from solution with ethanol u = 10% ranged from 96.0% to 108.0%. The biosensor was used for the determination of glucose in some food samples of dairy industry, and the results were consistent with those obtained with the commercially available glucose enzyme photometric kit.
Glucose oxidase as an analytical reagents
2015
Lee’s forecast, quoted above, has been proved true. The real impact of enzymes as analytical reagents, however, was not felt until the mid-1960s and early 1970s, de-spite the fact that in 1951 Stetter1 d scribed applications of impure enzymes to a variety of analytical problems. Even as early as 1845, Osann2 determined hydrogen perox-ide using peroxidase. The use of enzyme preparations as analytical reagents, both soluble or immobilized on inert carriers, has grown exponentially since the 1970s.3 The enzyme glucose oxidase (EC 1.1.3.4) is, without doubt, the one employed most widely. Its use is so frequently mentioned in the analytical literature that glucose oxi-dase is sometimes suspected to be abused rather than used. Such popularity is, how-ever, the result of a combination of factors. Glucose oxidase is a useful reagent for the selective determination of glucose, an analyte of clinical as well as of industrial interest. Moreover, it is used as an analyti-cal reagent as a marker...
Food Research International, 1998
A facile method for the immobilization of enzyme on the surface of the 96-well microtiter plate has been studied using avidin and biotinylated glucose oxidase (GOD). It was demonstrated that an alternate and repeated deposition of avidin and biotinylated GOD gave an activity dependent on the number of GOD layers deposited. The well, after deposition of 16 layers of GOD, was capable of determining glucose up to 1 mM. The enzyme activity of the well was retained for 6 months when the plate was kept at room tempearature. No signi®cant decrease in the activity was observed for 50 successive determinations of 1 mM glucose. These results suggest that the avidin/biotin system would be feasible to the immobilization of enzymes on the surface of a microtiter plate. The determination of glucose in various food samples using the above method is also described.
Enzymatic Determination of Glucose in Milk Samples by Sequential Injection Analysis
Analytical Sciences, 2009
The present work describes a comparative study involving two sequential injection enzymatic procedures for the spectrophotometric determination of glucose in milk samples. The determinations were based on the use of the enzymes, glucose oxidase and peroxidase, in solution or immobilized, and 4-aminophenazone and phenol as chromogenic reagents. In the first procedure, 8.4 IU of glucose oxidase and 0.5 IU of peroxidase were consumed in each determination. In the second procedure, 107 IU of glucose oxidase and 105 IU of peroxidase, immobilized in glass beads, were sequentially packed into the same reactor. The reactor allowed us to perform about 600 continuous determinations with no activity loss. The proposed systems allowed the determination of glucose up to 120 mg L-1 in milk samples with a precision, considering the RSD (%) values, lower than 3.5%. The results obtained for the two systems were comparatively evaluated against a routine enzymatic method, showing a relative deviation of less than 3%.