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26 De Smet plants are processing olive oil.
Origin
The olive, the fruit of the olive tree,  has been used for immemorial time for the production of olive oil.
The growing of olive trees, wild or organised, is mainly available in all countries around the Mediterranean : Spain, Italy and Greece, followed by France and Portugal are the main producers of olives.
The crop is done between October and December. The fruits foreseen for the production of first quality (extra virgin) oil are collected by hand or today in a manner that the fruits will not be damaged nor messy handled.
The selection of virgin oil qualities is mainly based on organoleptic characteristics, which will depend on the olive tree type, on climatic conditions, on quality of harvesting, on rapidity to process the fruit after crop, ... all subjective criteria which improve day after day.
The olive has an average weight between 4 to 12 grams and contains :
- the pulp represents 75 to 85% of the total weight and contains about 60% of water and 25% of oil (i.e. 40 to 60% on dry basis)
- the kernel represents 14 to 26% of the total weight and contains about 30% of water and 8 to 10% of oil (12 to 17% on dry basis).
End uses
Classification of olive oils :
- the virgin oils
the virgin oil is obtained from first cold press; it is used as ‘mouth’ oil and may be consumed as it is. Today a filtration with filter aid is generally performed, which eliminates the impurities and excess of moisture.
moisture and volatile < 0.2%
impurities insoluble in petrol ether < 0.1%
‘extra virgin’ with organoleptic index above 6.5 and acidity < 1%
‘virgin’ with organoleptic index above 5.5 and acidity < 2%
‘ordinary virgin’ with organoleptic index above 3.5 and acidity < 3.3%
- olive lamp-oil
was used long ago in petrol lamps
is obtained from a further hot pressing
organoleptic rate < 3.5
and an acidity > 3.3%
intended for refining
- refined oils
as long as refining doesn’t lead to alteration in the initial triglyceridic structure
- -olive oils
consist in a blend of refined olive oil and virgin olive oil as above
- olive kernel oils (olive pomace oils)
obtained by solvent extraction of the olive pomace, recovered from press after drying
has a high acidity rising sometimes up to 40-50% in extreme cases
the dried olive pomace contain :
- 30 to 45% of kernels
- 50 to 55% of pulps of which 5 to 7% of skin
moisture of olive pomace ranges at
± 35% after classical press but with a rising acidity before drying
± 50% after ‘pressing’ through a super-decanter with 3 phases; the acidity rises much slower and the pomace can be stored longer
± 65% after ‘pressing’ through a super-decanter with 2 phases; the acidity rises much slower and the pomace can be stored longer
before solvent extraction, moisture is decreased around 8 to 10%
the pomace contains 7 to 10% of oil after a single press or super-decanter but only 3 to 5% after a second press or super-decanter.
We have thus :
- crude olive kernel oil
- refined olive kernel oil with acidity < 0.3%
- olive kernel oil is a blend of refined olive kernel oil with virgin oil for consumption as it is. Acidity < 1.5%
Composition
It is a semi-siccative oil with variable composition depending on climate, grape maturity, time between process and grape crop. It contains :
Olive oils contain mainly :
- 70 to 80% of oleic acid
- 7 to 12% of palmitic acid
- 5 to 10% of linoleic acid
- unsaponifiables : 1.5 to 2%
- iodine value : 79-88
- saponification value : 187-196
- titer : 17-25°C
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