Olive Oil Extraction - Part 5

Alternative configurations
Some producers, in order to maximise product quality, choose to combine the traditional grinding method, the stone mill, with a modern decanter. This technique produces more selective grinding of the olives, reduces the malaxation time olive paste, and avoids the complicated cleaning of the olive press fibre disks. Because the use of the stone mill requires a loading and unloading phase, this extraction method is discontinuous, i.e. there times where the all machinery is stopped, therefore it is generally not used on a large commercial scale, being applied only at small scale olive mills producing high quality olive oil.

Consumer point of view
High quality olive oil can be obtained by all the methods if proper measures are taken. Olive oil quality is equally dependent on the quality of the olives themselves and on the time they have to wait from harvesting to extraction, in addition to the extraction method itself.

The 2 worst “enemies” of olive oil are: Oxygen and light. Once an olive is harvested, it should be pressed within 24 hours. Oxidation begins immediately upon harvesting. In the period between harvest and grinding, the fruits' enzymes are very active and increasingly degrade the endogenous oil, and therefore oil obtained after a longer wait is of lower quality, presenting higher acidity (oleic acid percentage).

In addition, if additional oxygen is allowed to interact with the olive paste during the extraction process, the acidity level will increase further. Sealed extraction methods are best to prevent the continued introduction of oxygen, as well as light to the oil.

Lastly, after extraction of the oil is complete, the oil must be stored in cool stainless steel silos that are pumped free of oxygen. This will ensure the quality of the oil; the integrity and stability of the chemical makeup of the oil.

Future prospects
The future of olive extraction points to reducing the negative aspects of the present methods, decreasing the degradation oil produced by the extraction process in itself.

Reducing the oxidation by performing part of the process of malaxation and the extraction under a controlled nitrogen atmosphere
Extracting the nut of the olive before grinding, this will reduce the release of oxidative enzymes present in this organ, and yield a pomace that is free from wood residues, making it possible to be used in animal feeding
Reducing the addition of water to minimize the washing of polyphenols
Improving the sinolea method, through an increase in the efficiency of the adsorption of the oil to the plates, thus reducing the need for the use of standard methods of extraction

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SuperFoods - Extra-virgin Olive Oil