Filtration of extra virgin olive oil
To keep the organoleptic and healthy characteristics much longer
After the olive processing in a modern continuous cycle mill with two or three-phase extractor and subsequent processing of the oil in the final separator, it has now been established the need for a further processing stage of the filtration.
Filtration is required because the oil leaving the final separator has a "hazy" appearance. The veiling is given by the fact that there is still water and solid fragments of olive inside. The quantity of these substances (water and solids in suspension) vary greatly from the type of extraction carried out in the mill, but the fact remains that over time, these particles will change substantially the flavor and organoleptic integrity of the oil, giving rise to sensory defects such as “sludge” favoring an early aging process of the oil.
The problem has always been known, so much so that traditionally a partial solution has been offered by transferring the oil from one tank to another, generally carried out on a regular basis. But this practice does not eliminate the problem immediately and above all it does not allow a guarantee to be offered to the consumer, who is tempted to purchase the oil in the immediately following period, when the installation process has only just begun.
Our company choice is to filter the oil immediately.
Although the unfiltered oil can offer an idea of greater authenticity to the consumer and to our customers, this remains only an idea.
A filtered oil, in fact, will be much more stable over time, it will tend to be more balanced on the palate and allows us to offer an additional guarantee to the consumer who will find the same tastes from the moment of purchase until he finishes consuming his pack of extra virgin olive oil.
In fact, the oil will remain fruity, bitter and spicy for much longer, offering amazing sensory sensations even several months after pressing the olives.
Personally, for our production quantities, we use a plate filter and filter sheets. The operating principle of the filter is very simple but at the same time very effective. There are oil inlet plates and oil outlet plates, the filter layer is placed between the two types. The oil is pumped by a transfer pump with nitrile impeller from a tank and pushed at a maximum pressure of 2 bar, so that it passes through the filtering layer. The destination tank is directly connected to the filter outlet.
It is a procedure that requires a lot of attention and is rather slow, depending on the cleanliness of the oil it is necessary to change the filters (roughing) between 300 and 500 liters of filtered oil. When the inlet pressure increases and you are no longer satisfied with the degree of filtration, it's time to replace the filters. A very slow operation that requires attention.
Going to the oil mill every day, we filter the oil every three or four days, as soon as we have a sufficient quantity to start filtration, trying to limit the waste of oil and the cost of the process.
Our filter has 40 plates measuring 20 cm by 20 cm in moplen, a material used in the food sector that is very safe and easy to clean. The structure is in stainless steel.
As far as the filter layer is concerned, a world opens up here. There are many types (cardboard, cellulose, etc.) with different degrees of filtration, from the roughing agent to the rinse aid. We use a roughing layer to avoid making too much filtration.However, the result seems excellent to us and our customers are very satisfied.