There’s far more to know about olive oil than whether it’s extra virgin. Variety, provenance, vintage and timing of the harvest all impact on the flavour, says FIONA BECKETT. But can you really tell the difference?

How many olive oils do you have in your kitchen cupboard? One? Two? An extravagent three? We tend to think (or certainly have done so in the past) of olive oil as a single commodity like butter rather than as a complex subject of connoisseurship like wine or cheese.

But there’s a great deal more to know that would vastly enhance our enjoyment of this kitchen essential. Many of the same factors are involved in olive oil appreciation as in wine – the variety of olives, the terroir, the timing of the harvest, the art of blending.

Charles Carey of London’s best known oil importer, The Oil Merchant, believes that variety is the most important. ‘There are several hundred, some of which are specifically for eating, some for making oil and a few that will do for both,’ says Carey.

‘Making oil from eating olives is like making wine with table grapes.’ Traditionally no distinction used to be made between the different types, and the olives were all thrown in together. ‘Producers now take a much more scientific approach, growing specific varieties in separate groves, often employing an agronomist to help them plant the right variety for the soil.’

Oils awarded a DOP (denomination of protected origin) are only allowed to be made from specified local varieties. As an example, Carey gave me two Colonna oils to taste which were quite distinctive in character; the DOP oil from Molise, which can only be made with varieties grown in the appellation, being the markedly more aromatic of the two.

Flavour factors

In Carey’s opinion, the differences between oils from different countries and regions are due more to these indigenous varieties than to variations in climate. Olives grown in Sicily, for example, such as Cerasuolo, Biancolilla and Nocellara del Belice, are different from the Frantoio, Moraiolo, Leccino and Pendolino grown in Tuscany. And all are distinct from the varieties traditionally grown in Spain such as Arbequina and Picual.

‘Spanish oils tend to be more mellow and less peppery than Tuscan ones, while Provencal oils have a touch of sweetness,’ Carey adds. As with wine, the waters are muddied by the fact that some varieties, such as Frantoio (‘the Chardonnay of the olive oil world’) have been successfully exported to the New World.

This gives rise to a similar debate as that which exists with wine as to whether oils are getting too homogenised. There are oil equivalents to the flying winemaking consultant, of whom the best known is Professor Giuseppe Fontanazza from Perugia, who has been employed by the South African wine and olive oil producer Morgenster to advise on where and what to plant.

Climate has an impact on the style of an oil, but it is increasingly weather that has the greater influence, especially in extreme years such as the winter of 1984-5, when frost wiped out more than 80% of the olive trees in central Italy.

‘A late frost or hailstorm can bruise the olives so they aren’t harvestable, while a hot, muggy summer can place olive trees in danger of fly attack which can rot the olives,’ explains Carey.

Lack of water – or an excess of it – may also make for an unbalanced oil. ‘If there is too much water content in the olives when the water gets separated from the oil during processing it can take the flavour of the oil with it,’ Carey points out. This is a danger that has to be guarded against where olive trees are irrigated, a practice becoming more common as summers get hotter and drier.

Where and when

Another factor that makes a crucial difference to how an oil tastes is when it is picked. There is an international trend towards earlier harvesting to meet the

demand for more fragrant, grassy oils.

‘The harvest in the northern hemisphere used to take place around the end of October and beginning of November. Now it’s much closer to the beginning of October,’ says Carey. ‘Some producers harvest olives when they’re quite green and still have a peppery taste; others leave them on the tree longer so the flavour is softer.

You get a greater yield if you harvest them later but if you leave them too long, as some more commercial producers do, they start tasting slightly fatty and greasy.’

They also tend to lose their individuality, something that worries Carey. ‘Italy has had too much influence on how oil should be produced in the rest of the world. Some French producers are harvesting their olives much younger than they used to in order to create a peppery oil that is similar in character to Italian oils.’

A further problem is that many lesser oils are blended and bottled outside their country of origin, so that there is no way of knowing not only where the olives were grown but when they were harvested.

Like grapes, olives deteriorate and oxidise rapidly once picked, and need to go to press within 24 hours of being harvested otherwise they can drop below the level of acidity (0.8g per 100g) that enables them to be classified as extra virgin olive oil.

Ideally, olive oil should be consumed as soon as possible after pressing but many oils spend extensive time in storage, in less than ideal conditions in transit, and end up on a brightly lit supermarket shelf. Which is true of wine too, except that the level of consciousness about the desirability of freshness in wine is higher.

‘The olive oil business is 10 to 15 years behind wine,’ says Judy Ridgeway, industry expert and author of Best Olive Oil Buys Round the World. It seems we still have a lot to learn before we become connoisseurs.

Written by Fiona Beckett