Olive harvest 2021 looking great
We are off and running with one of the best olive harvests the Hunter Valley has ever seen. By now the olives on the trees are starting to turn from a hard, shiny green to a softer yellow/green, then to pink, to purple and eventually to black.
While this colour change is going on, the amount of oil inside the olive is increasing. This is the stage where delivering olives to the mill for processing means bigger yields of oil out of the crop: always a good thing. Olives that are pricked and processed while under-ripe and predominantly green give around 4 to 6% olive oil at the end of the process - but mixed colour or black olives can easily give around 20% olive oil for the same weight of raw olives.
A modern olive mill (technically not a press and a centrifuge does the job of separating olive oil from the vegetable matter these days) takes around an hour from the olives entering the line where a leaf blower will remove and stray leaves, through a washer to remove dust, then a hammer mill to crush the olives into a paste and into a series of malaxers to gently stir the paste to allow the oil to separate.
After around 20 minutes of stirring, the paste is pumped into the fast-spinning centrifuge which will allow the lighter oil to be removed from the heavier and denser water and vegetable matter - known as pomace. The oil fraction is cloudy at this stage and needs time for the solids to settle out, giving clear oil.