Metrolab Blog

VELP Scientifica | How to effectively test Oxidation Stability of various types of Oils and Antioxidant Effectiveness

Various types of edible oils are available for cooking and for use in the kitchen. Oils range from plant oils, such as sunflower, soy, peanut, palm, coconut, olive oils, a mixture of oils to animal fats, such as salmon oil.
Antioxidants are typically used to enhance shelf life and preserve the quality of edible oils and fats. They suppress oxidation reactions by participating in or interfering with the lipid autoxidation reaction cascade through various mechanisms.
Different oils have different oxidation rates and antioxidants have different effectiveness in enhancing their shelf life and preserving their quality. With the VELP OXITEST Oxidation Stability Reactor analyses were conducted and key findings highlight distinguishing aspects for each oil tested.

Oxidation Stability of oils and addition of antioxidants
One of the most important quality alterations of food is due to oxygen absorption by the unsaturated fatty acids, free or esterified. The auto-oxidation of fats is a chemical reaction promoted by light, high temperatures, metal traces, and sometimes enzymes affecting the shelf life of the products.
Preservatives and other substances are added to counteract and slow this process of quality alteration of edible products. Antioxidants are typically used to enhance shelf life and preserve the quality of edible oils and fats. They suppress oxidation reactions by participating in or interfering with the lipid autoxidation reaction cascade.
Antioxidants used in oils and fats must be safe, stable, and effective at low concentrations.
Various types of oils were tested to analyze oxidation stability rates and compare formulas for all the oils with and without antioxidants:

  • Sunflower oil
  • Soy oil
  • Salmon oil
  • Oils mixture

The OXITEST Oxidation Stability Reactor was used to determine the oxidation stability of the various samples, without the need for preliminary fat separation.

The OXITEST Method and the analyses conducted on the various types of oils
The OXITEST Method is an internationally recognized analytical technique for the determination of the oxidation stability of food, fats, and oils.
The oxidation stability tests performed with the OXITEST reactor accelerate the oxidation process that in normal conditions can last weeks or months and provide fast, accurate, and reliable results.
The OXITEST speeds up the oxidation process because of two accelerating factors, temperature and oxygen pressure, according to the most common applications.
The instrument measures the absolute pressure change inside the two chambers, monitoring the oxygen uptake by reactive components in the sample and automatically generates an IP value.
The Induction Period (IP) is the time required to reach the starting point of oxidation. The longer the Induction Period, the higher the stability against oxidation over time.
With the OXITEST it is possible to create test reports for a single test or compare different analyses.
Each sample of oil was analyzed in duplicate and the OXISoftTM software option “Formulas Comparison” was used to make a comparison of the various oils with and without antioxidants.

Download the Application Note to uncover the analytical procedure and all the results