Posted on May 19, 2015 by Jenny Cromack
The oxidative stability of an edible oil simply refers to the oils resistance to oxidisation during the process of creation and its storage. An oils resistance to oxidisation determines the product’s shelf life and ultimately it’s quality, the lower the oxidisation of the oil generally the greater its quality. This is because the oxidisation of oils destroys essential fatty acid compounds, replacing them with toxic compounds and oxidized polymers.
Okay still with me…..numerous factors can influence the rate of oxidisation, unless the oil is locked away in an atmosphere free bunker its going to oxidize over time. Factors such as light, heat, the composition of the fatty acids and even other compounds in the oil such as metals and pigments can influence the oxidisation rate of oils.
Okay why is this bad for you and your diet? If you’re buying poor quality oils you’re not getting all the nutritional benefits reported from such products, you may in fact be working again your weight loss goals, or your hypertrophy goals. So here are the key factors affecting the oxidisation of oils and what you should look out for.
The Composition Of the Oils:
- The more unsaturated the oils the faster the oxidisation compared to less unsaturated oils
- Soybean and sunflower oils have quicker oxidisation rates than coconut oil or palm kernel oil
The Processing Of The Oil:
The relationship between the processing of oil and the oxidisation is well documented. Here are a few of the key points to look out for:
- Crude oil is more resistance to processing than refined oils
- Pressed oil seems to be more stable than carbon dioxide extracted oil
- Roasting of some seeds (Safflower seeds, sesame seeds) before oil extraction, improved oxidative stability during processing.
Temperature and Light Conditions:
- Decomposition and auto-oxidisation of some oils increases as temperature increases (hence frying oils could potentially be bad)
- Light of shorter wavelengths has a more negative effect on the oxidisation of oils, partially transparent plastic bottles have a negative effect on the oxidisation of the oils.
I hope this helps with your oil selection, most oils are a very healthy source of calories and are packed with essential fatty acids, many steps can be taken to optimise theses benefits, as can be seen above.