Olive oil is a staple component of Mediterranean food and is lauded for both its flavour and health properties. However the different grades and varieties can be confusing – for example what is the difference between virgin and extra virgin? What does cold pressed mean? A quick run down on how to make olive oil can explain the mystery.
How to make olive oil commercially
Commercial producers choose varieties of olive tree that produce fruits with a particularly high yield of oil. The trees are carefully pruned to reach their most productive mature state, at which point the fruit is harvested – machine harvesting is quicker and therefore cheaper but hand harvesting is said to produce a better result. Either way, the best oil comes from fruits which reach the mill as soon as possible after picking.
The olives are cleaned to remove leaves, twigs and any other debris before being crushed – stones, flesh, the whole fruit. What comes out of the mill is a paste, which then goes through a press, a process known as ‘malaxing’, to separate the oil from the waste material. The oil is bottled according to its commercial grade.
The bottle labelling indicates how much processing the oil has been through, with extra virgin representing the purest and best oil. No heat or chemicals are used to process virgin or extra virgin. Cold pressed is oil that has been produced without being heated and is considered both nutritionally and flavour superior. Basic olive oils have a more subtle flavour and are more often used in cooking, whereas extra virgin is more popular drizzled on food or for dipping. The better oils have a lower percentage of acidity and are therefore ideal as a base for
How to make olive oil at home
If you are lucky enough to have olive trees at home, you can try making your own oil. With a few basic pieces of equipment and follow the same fundamental process for how to make olive oil commercially. You’ll need a lot of olives and a suitable grinder – a standard food processor won’t be strong enough to crush the stones. The oil can be extracted from the resulting sludgy mixture using a centrifuge or a press, which simply uses pressure to pass the olive pomace mixture through a series of filters. An oil and water mixture comes out of the bottom of the press, which is easy to separate, leaving beautiful, pale green oil. The oil will keep for up to two years in sterilised, properly sealed bottles. Store in a cool, dark place as quality can be affected by heat and light.