Polyphenols in Extra Virgin Olive Oil
admin | February 9, 2010What are Polyphenols?
Extra virgin olive oils contain a healthy suite of naturally occuring antioxidants called polyphenols. While polyphenols are widely distributed in nature, being found in many fruits and vegetables and in healthy beverages such as green tea and red wine (to name a few), most of the polyphenols found in extra virgin olive oil are unique. I guess this isn’t surprising as the olive oil types have to be fat soluble while the other types need to be water soluble. Read on to find out what role they play in the taste, healthfulness and shelf life of the extra virgin olive oil.
What do Polyphenols Contribute to the Taste of Extra Virgin Olive Oil?
Most of the phenolic compounds found in olive oil are not volatile, so they do not contribute to the aroma or flavour of the oil. However, they are bitter and pungent (peppery), so they add significantly to the unique taste of many extra virgin olive oils. It is now known that some types of polyphenols are bitter while other types produce the peppery, or throat catching sensation. The major contributor to pepperyness in extra virgin olive oil was discovered in 2002 and has since been given the name “oleocanthal”. It’s such an important phenolic health wise that I’m reserving a dedicated post to it.
The Role of Polyphenols in Olive Oil Shelf Life?
Polyphenols are powerful antioxidants so by their nature they react very readily with oxygen. Therefore any oxygen molecule that finds its way into the oil will react with any polyphenol it encounters before reacting with the fat molecules. That’s how polyphenols naturally protect the oil from getting tired and (ultimately) rancid. However as each polyphenol can ‘do its thing’ only once, sacrificing itself in the process, they are naturally used up over time. In fact, even under good storage conditions, around 40-60% of the polyphenols of an EV oil are used up in the first 6 months. This protective role of polyphenols also explains why milder oils (which are low in polyphenols) generally have shorter shelf lives than the more bitter and peppery robust styles (which are rich in polyphenols).
The Role of Polyphenols in Health
Free radicals can be thought of as oxygen molecules on steroids! They damage human cells causing aging, but in extreme cases can also result in cell mutation leading to certain cancers. Polyphenols are strong antioxidants and just love to scavange and mop up the free radicals from our bodies. Free radicals also oxidise LDL (the proteins that carry the “bad cholesterol” around in the bloodstream), which eventually leads to plaque deposits forming on the walls of our arteries. Olive oil antioxidants can disrupt this first important oxidative step which ultimately leads to a reduced risk of coronary disease.
In short, the polyphenols found in extra virgin olive oil have the capacity to react with the nasty free radicals before they adversely react with you!
What About Other Edible Fats
Canola oil, vegetable oil and olive oils such as ‘Pure’ , ‘Light’ and ‘Olive Oil’ contain essentially no polyphenols, so they do not provide the same potential benefits of extra virgin olive oil. The refining process common to all these oils strips them away. In some cases, artificial antioxidants like ascobyl palmitate are added to the refined oil to improve their shelf life. While this is just a fat soluble version of Vitamin C, it probably doesn’t provide any health benefits.