PDFdnwIcon Testing Service Catalog (PDF) Print Email


Price of the test:

$250 per analysis

Acceptable Matrices:

cereal grains, doughs, pastas, and vegetables

Limit of Detection:

0.01 units/gram

Sample Size Requirements:

20 grams


UV/Vis spectrophotometer, homogenizer, microplate reader

Reportable Units:

units per gram. 
One unit is defined as the change in absorbance at 470nm per minute from the formation of tetraguaiacol.

Turn Around Time:

15 business days

Is Rush Available?


Method Reference:

Britton Chance, A.C. Maehly, "Method in Enzymology", Assay of catalases and peroxidases. Vol 2, Academic Press, New York, 1955, pp. 764-775.; AOAC 963.27

Method Description:

Samples are homogenized and enzymes are extracted into a cold, pH 6.5 buffer.  A protein determination by the Method of Bradford is performed on the enzyme extract (supernatant) to normalize subsequent enzyme results to the efficiency of the protein extraction.  The enzyme extract is mixed with hydrogen peroxide, guaiacol, and calcium.  Peroxidase activity is measured spectrophotometrically by the rate of formation of tetraguaiacol at 470nm.

Information Required by Submitter:

Estimates of activity if available
Composition of sample matrix

Additional Information:

Peroxidase is an enzyme that can catalyze the cross-linking of phenolic residues by H2O2 resulting in undesirable color changes (graying) and the potential generation of off-flavors in a food product.  Determining the average level of peroxidase in different cultivars can help guide breeding decisions.  Additionally, because peroxidases are relatively stable enzymes, they can serve as an indicator for the efficacy of enzyme inactivating treatments in grains and flours (e.g. heat treatment, chemical treatment, etc.)

Please keep and ship samples frozen if possible.