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Beware of fake EVO oils: What is a good level of acidity for extra virgin olive oil?

by Carmine Rizzo 27 Oct 2022
The quality of an extra virgin olive oil can be objectively determined by assessing the quantity and composition of fatty acids, tocopherols, vitamins. Other elements such as acidity also contribute significantly to determining this level in a given product.


Polyphenols are antioxidants that give olive oil its rich, deep colour and many health benefits. They also create a sensory experience for the palate by adding an unusual salty flavour to this otherwise bland vegetable-based sauce or garnish that can be enjoyed as part of the meal if used wisely!
A recent study has discovered more about how polyphenol interacts with our bodies: it shows promise in the fight against cancer because these compounds interrupt cell growth at different stages depending on their chemical composition (i.e. some will stop cells from reproducing while others may block energy production). So next time you cook dinner think outside those boring old tubs of margarine - try using extra virgin oil instead!

Oil Peroxides

You may have heard the term 'oxidative ageing' before, but do you know what it means? Oxidative ageing is when peroxide levels increase and results in an ageing appearance on your skin. Peroxidation occurs naturally with UV exposure or by cooking oil; however, these processes can be accelerated by overcooking food (such as frying) which generates free radicals that lead to damage of our body cells through inflammation response proteins called prostaglandins - this leads us towards a vicious circle where more toxins unnecessarily enter the circulation because they are produced faster than we eliminate them!

Extra virgin olive oil acidity limit

The acidity limit for an extra virgin olive oil is 0.8%, but in a quality product the values are significantly lower (0-3%). with some being as low as 20 or 30 millilitres per thousand grams (mL/kg). This means that you will also find more than 2% and up to 3%. However, if there is anything strange about its taste, then there is a high chance that it has gone beyond this amount due to unwanted bacterial growth.

Research on preserving the acidity of extra virgin olive oil

With increased exposure to oxygen, even if it is only through the process of opening and closing a bottle, there is more chance of oxidative damage (rancidity). Even small amounts of oxidation make a difference in the flavour and shelf life of your oils. It is best to keep your oils tightly sealed in a cool environment away from light. It is also recommended to date them once opened so you know how long they have been open/exposed to air, although this is not always possible.

A 2007 study by the University of California's Department of Food Science and Technology found that acidity levels can be measured accurately, making it possible to measure their progress as they oxidise. The researchers used nuclear magnetic resonance (NMR) spectroscopy to determine how many molecules were present and discovered a direct correlation between acidity level and oil ageing. Not only did they find that this method could easily measure the acidity of an oil - they also discovered that it could be used to track how fast an oil is degrading.The study provides new information on how and why oils age, and what causes flavour degradation over time. It directly correlates the acidity of an oil with its oxidative state, something that has never been done before. Previous studies on ageing have been limited to sensory analysis or oxidation by-products. In this study, acidity concentration was measured directly and found to increase over time in direct proportion to other markers of oil degradation.

In olive oil, its freshness is determined by hydroxytyrosol and tyrosol [the good antioxidants] that should not be present if the oil is rancid. 'It has long been known that it is possible to determine the quality of virgin olive oils based on their content in these two compounds,' says research director Nuria Larrañaga of the Olive Center at UC Davis, who led the study. The new technique determines how much antioxidant remains after exposure to light and heat (or storage conditions) by measuring the amount of two degradation products. How do you know if your oils are getting old or rancid? The study found that within 48 hours, there is a 30 per cent loss of volatiles in extra virgin olive oil. After one month, there is a 40 per cent loss and after three months a loss of almost 60 per cent.
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