How to choose olive oil in a supermarket

Choosing olive oil in a supermarket can be overwhelming. We're faced with a wall of conflicting bottles, each proclaiming "freshly pressed!", "single estate", or "100% Italian olives!".
 
Let's assume we're buying extra-virgin - which means (in theory), juice from the olives extracted by mechanical means (i.e. crushed), rather than using chemicals to extract the juice from later crushing.
 
As you probably know, not all extra-virgin is created equal. So what should we be looking for on the label?
 
The harvest date!
 
This is the best indicator of quality. Olive oil is essentially a fruit juice, made by pressing the juice from olives, with (hopefully) nothing added. It's best when it's fresh, so if you want a good oil, it must be from the most recent harvest (Oct-Feb each year).
 
The taste, aroma, pungency, health benefits (concentration of polyphenols, the good antioxidants) all deteriorate with age. An oil over 12 months old will have lost a lot of quality.
 
Most cheaper bottles will not display the harvest date. The oil will likely be from earlier harvests - avoid if you want a good oil.
 
Early harvest
 
This is a tagline you'll see on some of the more expensive oils.
 
Around the Mediterranean, (where 99% of the oil sold in the UK is from, probably) olives are harvested between October-February each year. "Early harvest" refers to olives harvested October-November, when they're just ripe and still green. This produces a higher quality oil with more intense flavour and a higher concentration of polyphenols.
 
As the olives aren't as juicy in early harvest, they produce less oil. So the oil will cost more.
 
Single estate
 
Single estate means all the olives in this oil were grown on the same farm, which is essential to have any sort of quality control, so this is a minimum requirement for a decent oil. Bottles that say "A blend of oils of European Union origin" will not actually taste of olive oil because they've likely been mixed with vegetable oils somewhere in the supply chain. Which brings me onto...
 
Fraud
 
Olive oil is, sadly, one of the most adulterated food products in the world. It's estimated that 80% of the olive oil on supermarket shelves is 'fake'. "Watering down" extra-virgin olive oil with cheaper vegetable oils is common practice. How can you avoid this? Well, be realistic with price. The simple fact is that it's impossible to produce real extra-virgin olive oil and sell it for under £5 a bottle.
 
The colour
 
The greener the better, right?
 
Not necessarily. This is one of the biggest olive oil myths out there. The colour will tell you nothing about an oil's quality.
 
The colour will differ based on factors like the climate, soil and the type of olive used! This is why in olive oil competitions, sommeliers (yes olive oil sommeliers are a thing!) sip from blue cups, so they can't be influenced by the oil's colour!
 
Glass or plastic bottle?
 
A producer will not put a good quality oil in a plastic bottle. Nor would they put it in a clear bottle, as exposure to light affects the oils quality. So look for oils in a dark bottle, or better still - and opaque tin!
 
Olive variety
 
There are 100's of olive varieties in the world, each producing oils with different characteristics. Most olive oils come from the same 10 or so varieties ('juicier' varieties that yield more oil). But this has led to a monoculture of olive trees across the Mediterranean and huge loss of biodiversity. If you're buying an oil made from a rarer olive variety, it may be more expensive to produce, but its taste will be unique.
 
Is Italian the best?
 
Italian olive oil certainly has the best reputation. But no, good olive oil is down to the producer, not the country. It's also down to personal preference, you may like the taste of a particular region-specific olive variety. Climate definitely affects an oils flavour, dry and hot climates will produce different oil to wet and milder climates.
 
Conclusion
 
Hopefully that explained a few questions, in short:
 
  • Olive oil is best when as fresh as possible! Look for the harvest date on the bottle, right now you want 2020 harvest.
  • Early harvest oils are better quality.
  • Single estate is a basic requirement for quality control.
  • It's estimated that 80% of olive oil on sale today is fake! If the price is too good to be true, it usually is.
  • There is no correlation between the oil colour and it's quality!
  • Don't buy good oil in a clear bottle.
  • Take note of the olive variety in the oil. Most will be a blend of varieties, single variety is generally more prestigious for a purer taste.
  • Good olive oil is down to the producer, not the country.