Peroxide Value Test

Method description

The fat or oil sample is dissolved and an excess amount of potassium iodide is added. Peroxides present oxidize a portion of the iodide forming iodine. The iodine is titrated with sodium thiosulfate and the peroxide value is calculated.

The hydrogen ion concentration of the sample is determined by measuring the electrical potential produced by an electrode that responds to hydronium ions. The electrical potential is converted to hydrogen ion concentration expressed as the negative logarithm of its concentration (pH). If dissolution or dispersion of the sample is necessary (a 10% solution), carbon dioxide-free water is used.

Acceptable matrices

Fats, oils, flours, nuts, animal foods, and mixes

Products should be at least 3% fat in order to obtain reportable results.

Unacceptable matrices

Egg yolks, low-fat samples, or any matrix from which the fat cannot be extracted using petroleum ether

Limit of quantitation

N/A

Equipment

Electronic titrator

Method reference

AOCS Official Method Cd-8-53
AOAC Official Method 965.33

Reportable unit

meq/kg of fat – millequivalents of peroxide – oxygen per/kg

Sample size requirements

Please provide a sample of at least 100g to ensure results are representative of the sample submitted.

At least 0.50 grams of fat extracted from food products is needed to run this analysis.

Samples should be kept frozen until analysis.

Additional information

This test is ISO/IEC 17025 accredited through A2LA, Certificate # 2769.01.

Peroxide value is the most commonly used assay for measuring the state of oxidation in fats and oils and its value measures the oxidative rancidity or degree of oxidation of the fat/oil, but not its stability.

The peroxide value is determined by measuring the amount of iodine liberated from a potassium iodide solution at room temperature. The liberated iodine is expressed in units of milliequivalents of peroxide-oxygen per 1000 grams of fat.

For PVP we will extract up to 100 grams of the product. It is necessary to extract at least 1 gram of fat from the sample to run the analysis. Therefore, the product should be at least 3% fat to make this method applicable. If your product is low fat, Hexanal testing might be a better choice for tracking rancidity.