Bins of harvested frantoio olives
Olive Processing
Processing starts with harvesting the olives. With the short growing season
in Central Otago it is rare that there is the opportunity to leave the olives on
the tree to ripen fully, ie black skin and flesh. Consequently the olives are
picked relatively unripe, typically with approximately one third green/yellow
green, one third coloured and one third black skinned.
As olives ripen the oil content increases, but other components, in particular
the anti-oxidants decrease. By picking relatively unripe olives we sacrifice oil
yield but produce an oil high in anti-oxidants with moderate to intense
fruitiness with good levels of bitterness and a peppery finish.
The olives are harvested by hand using plastic hand held rakes to rake the
olives off the trees onto nets laid on the ground. Once sufficient olives have collected on the nets they are transferred to
bins for transport to the processing plant. To preserve the quality of the olive oil the olives are processed without delay in
the company’s own olive press.
During the first stage of processing the olives are washed and any
leaves collected with them removed. The olives are then crushed,
pits and all, in a hammer mill to form a paste, which is gently
kneaded to release the oil and to coalesce it into larger droplets.
After an hour’s kneading the paste is fed to a high speed centrifuge
where the oil is separated from the solids and vegetable water.
The olive oil discharging from the centrifuge always contains a small
amount of olive paste. To remove this the oil is stored overnight to
allow solids from the paste to settle out. It is then decanted off and
stored under food fresh nitrogen. The purpose of the nitrogen is to
minimise oxidation of the oil during storage. Prior to bottling the oil is
filtered to remove any remaining solids, which might have a
deleterious effect on the oil quality.
The olive oil is bottled as required into 250ml or 750ml green bottles. The bottles are purged with food fresh nitrogen prior
to filling. The coloured bottles and the purging with nitrogen are employed to protect the oil during storage to ensure that it
reaches the consumer in the best possible condition.
Hand picking olives The Oliomio 150 olive press