GrasasYaceites 1-57. pdf

Trends in olive oil production
Trends in olive oil production

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– Fruit storage
– Paste preparation
– Milling
– Malaxation
– Solid phase separation
– Press
– Centrifugation
– Two way system
– Three way system
– Liquid phases separation
– Natural decanting
– Centrifugation
– Oil storage and maturation
3. PREVIOUS OPERATIONS
Fruit reception is one of the most important
steps in the oil extraction process since the olive
fruit should be characterized in order to determine
the next step. It has to be done by a reception area
manager, who has to visually evaluate the fruit
characteristics and decide how to manage each
fruit pool.
One of the basic practises to obtain quality oils
is good fruit management where the fruit has to be
cleaned and washed, depending on the
characteristics of the fruit (Uceda et al., 1989).
Olive cleaning consists of the elimination of
waste particles that can be found among the olives,
leaves and small branches, with lesser density than
fruits. The method allows the waste to be removed
by flowing an air stream through the fruit. Other
machines used to clean are the branch removers to
eliminate branches that passed the air stream.
The ground-picked fruits, and sometimes the
tree-picked fruits, contain other waste such as soil,
slush and small stones. Their separation is needed
since they produce undesirable machine abrasion
and can even break, reducing the process yield.
They are eliminated using olive washers based in a
water stream with a determined flow rate,
sometimes helped by a air stream, that moves the
fruit floating on the water while the heavier parts
deposit on the machine bottom where they are
removed back stream by shaking sieves or a screw.
In general, as reported by CIFA ‘Venta del Llano’
researchers, the tree-picked fruits should not be
washed, only when needed, because of the special
fruit characteristics. Since the extractability is
reduced because of an increase in fruit moisture
and lower oxidative stability and sensory score due
to a reduction in phenol content (Hermoso et al.,
1991a).
The olives, after washed and cleaned, have to
be stored until their milling in a storage hopper.
Their storage capacity should be calculated in order
to regulate the fruit entrance in the oil mill. During
prolonged storage the fruits show some alterations
produced by spontaneous hydrolysis, enzymatic
activity or micro-organism development (fungus or
yeast) that reduce the oil quality from a chemical
and sensory point of view (Camera et al., 1978).
These alterations are greater as the storage period
is longer (Rodriguez de la Borbolla et al., 1959). To
reduce the negative effects of the storage period
post harvest techniques have been applied as low
temperature storage although the high cost limit its
industrial application (Garcia et al., 1996). From
CIFA ‘Venta del llano’ we recommend the
immediate olive processing although in the
beginning of the crop year the so-called ‘difficult
pastes’ can appear. For these conditions the use of
technological coadjuvants such as micronized talc
may be needed.