Step 1: - Harvest
Each olive variety has its own optimum ripeness. Harvest your olives at the point of ripeness most suited to your variety for the following reasons:
A. Reduce the acidity level of your oil (necessary for EVOO)
B. Increase shelf life of bottled oil
C. Increase organoleptic (good taste) properties of the oil
Step 2: - Cleaning
Olives will be removed from the trees with dirt, leaves and small twigs still attached. These must be removed prior to processing. Even though research has shown that a few leaves and small twigs will not dramatically change the quality of the oil processed, they will have some detrimental effects on your processing machinery. Cleaning and leaf removal is definitely recommended for best results.
Step 3: - Washing
The olives have now had some preliminary leaf and twig removal and it is time to wash them thoroughly to prevent any problems with taste or soil borne organisms. Any additional loose matter can now be removed and the clean olives can be augered into the Malaxer.
Step 4: - Malaxing
The olives are then fed into the Malaxer where they are ground and mixed into a paste. The mixing process is allowed to continue sufficiently long enough to allow separation of the oil from the paste. Some manufacturers also recommend that you allow some rest time and then repeat the malaxing process to create the greatest separation of oil and paste. This mixture is then pumped from the Malaxer to the Decanter.
Step 5: - Decanting
The Decanter is actually a high-speed centrifuge that uses relative specific gravity to separate the oil, paste and vegetable water from one another. In most models the water and oil are separated and the paste is pumped off as well to be used in other processes. The decanting process is an entire subject unto itself and for the sake of brevity, we will only touch on the basic points.
Step 6: - Filtering and Bottling
In some processes the oil is further filtered and then pumped to a holding tank where it is immediately bottled into retail units. Some growers believe that much of the flavor of the oil is lost by further filtration. Others contend that removing sediment that accumulates in the oil will greatly increase the shelf life of the bottled oil.