All the latest news from the farm and the kitchen
by Sam Fairs, February 23, 2017
Rapeseed is small and black, much like a poppy seed, with a golden-yellow centre. The oil is locked up in the carbohydrate at the centre of the seed, and cold pressing is the method we use to extract this oil, by gently squeezing it out of the seed.
When the crop is harvested, it collects in the combine’s ‘hopper’, which can carry around 12 tonnes of rapeseed. When the combine is full, we empty its contents into a trailer, which is towed by our tractor to a big barn on the farm.
At the farm, the rapeseed is emptied in to a huge barn with a specially-designed slatted floor. Air is blown under the floor and through the slats, which helps to keep the rapeseed cool and in optimum conditions while it waits to be pressed.
Next, we clean the seed to remove any bits of straw, weed seeds and stones that may have gotten through the combine. Then, when the seed is completely clean, it’s ready to press using something known as a ‘screw press’.
A screw press is, as the name suggests, just like a big screw that’s constantly turning at a slow speed. The seed is drawn in at one end and pushed to the other end as it turns, with a small opening through which the seed is pushed. As the seed is pushed through this opening, the pressure around the screw builds and squeezes out the oil. Then, the oil is pushed through the casing around the screw, and collected in a channel below.
The ‘meal’ that comes out of the end of the press – leftover once the oil has been squeezed out – is collected and used for animal feed. This is very high in protein, and still contains about one third of the oil.
Next, we pass the oil through two filters – a paper filter and a backing board – to remove any leftover bits of seed. Then, the oil is stored in stainless steel vats and transferred to our bottles to be sold in the shops or in our online store.
Most refined oils are extracted using chemical, petroleum solvents and high temperatures. Although this process is highly efficient (abstracting 98% of the oil from the seed, compared to our 70%), it leaves the oil with a very unpleasant taste, so the oil has to be bleached and deodorised to remove this taste and colour. The refining process also destroys all naturally-occuring vitamins and antioxidants, so these are added back into the finished oil at the end of the process.
Hillfarm cold pressed oil is released without any heat treatment, with the only heat coming from the friction created during the pressing, which never exceeds 35°C. This helps us to retain the high quality of the oil, including all the natural flavour, aroma, and nutritional value.
Give our cold pressed rapeseed oil a try, and let us know what you think!