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Amperometric determination of L-lactate based on entrapment of lactate oxidase on a transducer surface with a semi-permeable membrane using a SIRE technology based biosensor. Application: tomato paste and baby food.

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Author

  • Kirstin Kriz
  • Linda Kraft
  • Margareta Krook
  • Dario Kriz

Summary, in English

Determination of dissolved L-lactate in tomato paste and baby food samples using a SIRE-based (sensors based on injection of the recognition element) biosensor is reported. The measuring principle is based on the use of a small amount of enzyme, which is injected into an internal delivery flow system and held in direct spatial contact with the amperometric transducer by the use of a semipermeable membrane. Measurements are based upon the reversible enzymatic conversion of L-lactate to pyruvate and hydrogen peroxide by lactate oxidase. Differential measurements are performed in which the samples are measured in the presence and absence of enzyme allowing for control over matrix interferences present in crude samples. The linear range investigated for the determination of L-lactate in tomato paste and baby food was 0-0.1 mM using a lactate oxidase concentration of 22 U/mL. Samples were diluted with buffer prior to biosensor measurements. The L-lactate concentrations of the tomato paste and baby food were determined to be 1.02 +/- 0.02 mM and 2.51 +/- 0.10 mM, respectively, using the standard addition method. The repeatability for tomato paste and baby food measurements was 2.5% (RSD, n = 15) and 4.0% (RSD, n = 15) and the reproducibility was 13.0% (RSD, n = 45) and 3.0% (RSD, n = 45), respectively. The concentration of dissolved L-lactate can be used as a measure of freshness in the food industry. All biosensor measurements were compared with measurements from an established spectrophotometric assay (Boehringer Mannheim). It was found that the biosensor had good correlation with the spectrophotometric method. The biosensor gave 12% higher values for the tomato paste measurements and 2.5% higher values for the baby food measurements. However, a distinct advantage of the biosensor is that it can perform L-lactate measurements within 3 minutes, whereas the spectrophotometric assay requires a 35-minute measurement time.

Publishing year

2002

Language

English

Pages

3419-3424

Publication/Series

Journal of Agricultural and Food Chemistry

Volume

50

Issue

12

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Agricultural Science, Forestry and Fisheries

Keywords

  • Artificial
  • Membranes
  • Lactic Acid : analysis
  • Infant Food : analysis
  • Infant
  • Human
  • Fruit : chemistry
  • Food Industry : standards
  • Immobilized
  • Biosensing Techniques
  • Enzymes
  • Mixed Function Oxidases
  • Quality Control
  • Reproducibility of Results
  • Tomatoes : chemistry

Status

Published

ISBN/ISSN/Other

  • ISSN: 0021-8561