Malaxation
Encyclopedia
Malaxation, a stage in olive oil extraction
, is the action of slowly churning or mixing milled olive
s, typically for 20 to 40 minutes. The churning allows the smaller droplets of oil
released by the milling process to aggregate and be more easily separated. The paste is normally heated to around 27°C during this process. Oil yield is proportional to the temperature and mixing time. However, the use of higher temperatures and longer mixing times increases oxidation of the oil and therefore decreases shelf life, so a compromise must be struck. Also, the usage of higher temperatures does not allow for the labelling of the oil as "cold extracted", a term used widely as a marketing tactic, especially in the European Union
.
It is now possible with newer equipment to use a blanket of inert gas
such as nitrogen
or carbon dioxide
over the olive paste, which greatly reduces oxidation. This allows for an increased yield without compromising the quality of the oil.
After malaxation is complete, the paste is sent to a phase separator. Nearly all producers use a decanter centrifuge for this process. Traditionally the olive oil was separated from the paste using a large press that was either screwed down or weighted with rocks.
Olive oil extraction
Olive oil extraction is the process of extracting the oil present in the olive drupes for food use. The oil is produced in the mesocarp cells, and stored in a particular type of vacuole called a lipo vacuole, i.e., every cell contains a tiny olive oil droplet...
, is the action of slowly churning or mixing milled olive
Olive
The olive , Olea europaea), is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin as well as northern Iran at the south end of the Caspian Sea.Its fruit, also called the olive, is of major agricultural importance in the...
s, typically for 20 to 40 minutes. The churning allows the smaller droplets of oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
released by the milling process to aggregate and be more easily separated. The paste is normally heated to around 27°C during this process. Oil yield is proportional to the temperature and mixing time. However, the use of higher temperatures and longer mixing times increases oxidation of the oil and therefore decreases shelf life, so a compromise must be struck. Also, the usage of higher temperatures does not allow for the labelling of the oil as "cold extracted", a term used widely as a marketing tactic, especially in the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
.
It is now possible with newer equipment to use a blanket of inert gas
Inert gas
An inert gas is a non-reactive gas used during chemical synthesis, chemical analysis, or preservation of reactive materials. Inert gases are selected for specific settings for which they are functionally inert since the cost of the gas and the cost of purifying the gas are usually a consideration...
such as nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
or carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
over the olive paste, which greatly reduces oxidation. This allows for an increased yield without compromising the quality of the oil.
After malaxation is complete, the paste is sent to a phase separator. Nearly all producers use a decanter centrifuge for this process. Traditionally the olive oil was separated from the paste using a large press that was either screwed down or weighted with rocks.