Monday 22 December, 2014 by Uncle Spike
So, we have now covered the end to end process, from olive growing through to oil production. But how much oil is produced?
Oil production varies based on a number of factors – here’s a quick unscientific summation from what I have learned from having my own farm:
Like most natural crops, the weather plays a big part in Mother Nature deciding how much fruit will be generated. If we get rain mid summer (rare, but can happen), the fruit matures too early, but lowers the oil yield (same with over-watering). Under-watering just stunts the growth as you’d imagine. High temperature 42C (108F) strong winds that gust 20 hours a day for perhaps ten days in early July can play havoc with the young fruit (as well as your mind).
Healthy trees produce much more fruit of course, but they need insecticides, pesticides and fungicides sprayed four or five times a year at least. I do none of those. They cost serious money, but also, I don’t like to add chemicals to what our family consumes. The most I use is Bordeaux-Bulamacı every few years, which is copper-sulphate powder mixed with water and considered organic .
There are numerous commercial products that can be sprayed to create more flowers, stop buds dropping, keep a higher percentage of new fruit from falling, and later on to keep the fully formed fruit in place in order to mature the fruit and increase the amount of oil per kilo of fruit.
There are many many different types of olive trees. We have four types here, each with their own properties of size, taste, and of course, oil-producing characteristics.
This DOES matter, as the soil type, climate, drainage, and sun position all influence crop potential. For example, if you take just 100 kg (220 lbs) of olives to the factory, that isn’t enough to secure a single machine load, and so they will give you ‘stock’ oil based on the weight of your olives, AND your picking location. Each village in the area has a listed yield rate; varying by up to 50%. So yes, location matters.
Once the fruit has matured, the greener the olives, the greener the oil. Simple really. But it also takes more olives to achieve the same volume – by up to a factor of two – hence the commercial operations rarely do that, or you’d pay much more per tiny bottle.
Maturing the fruit on the tree, or on the ground as I do (as I haven’t the capacity to pick everything in one week as I work alone (no troop of workers or large family on tap). Maturing alone can increase the yield by ten percent.
So what was our yield?
This year I took 610kg (1345 lbs) of olives to the factory. I picked more than that, but some didn’t survive the maturing process, and of course some were used for table olives, either cured in water or with salt.
The net oil yield was 91kg (200 lbs) in terms of weight.
Density of liquids vary too, with water as the base where one kilogram of water equates to one litre of water. However oil is less dense, and again varies by oil type etc. etc.
Our olive oil density is around 1:1.15 to 1:1.20 so that meant that the 91kg (200 lbs) of oil had a physical volume of 105 litres, which is 23 Imperial Gallons, or 27.7 US Gallons.
Certainly enough for the needs of our family and friends. However, next year will be an ‘off year’, so the crop could well be just 15-20% of that, so I have to be careful to not squander it.
That was a good result, and I’m really pleased as it represents a yield rate of 5.8 kilograms per litre or 48.5 lbs per US Gallon – my best yet 🙂
To put that into some sort of context, one year I picked mature but primarily green fruit, and matured it for just two weeks. The resulting oil was superb in terms of taste, a bright almost luminous green, but the yield rate was 11.5 kilograms per litre or 96.1 lbs per US Gallon.
Learn something every day?
Well, there ya go… 🙂