Just like other basic ingredients, people don’t tend to think much of where vegetable oil comes from until they don’t have it. There are a few brave souls however who attempt to find ways of doing things like extracting vegetable oil all on their own. We know that people have been extracting oil from vegetables for thousands of years, but modern methods have little in common with traditional means. The means of producing vegetable oil on a small farm operation will look almost nothing like industrial oil extraction.
With rising shipping costs and the growing concerns over industrial agriculture, there’s good reason to think we will not always have access to cheap vegetable oil. We’ll first consider the commercial extraction methods, compare these with more traditional means, and then find out how do-it-yourself vegetable oil extraction can work for the home gardener.
Commercial extraction methods
The vegetable oil we buy in stores is processed in one of two ways. It is expelled through force, or it’s extracted by chemicals. Chemical extraction uses a solvent, commonly hexane derived from petroleum. This solvent evaporates off, leaving the oil. This is currently the cheapest and quickest way, so it is used for making the cheapest vegetable oils, both for industries and consumers.(1)
The crude oil from most oilseeds is then processed through heating, freezing, or hydrogenating depending on the desired qualities. Salad dressing oils will be filtered at near-freezing temperatures. Margarine oils are heated under pressure and hydrogenated for solidity. Other oils are hydrogenated to raise their smoking point.(2)
Expeller-pressed oil is closer to traditional processing, and it provides the highest quality and most healthy oils. A modern olive oil mill can process over 4,000 pounds of olives an hour and consists of two parts, a grinder and a storage facility. Oils produced in this way have to be protected from oxidation. As you can imagine, these are huge operations.(3) Cold-pressing also slows down production quite a bit. One industrial expeller on the market can process 1.4-2 tons using hot press and .7-1.5 tons for cold press, depending on the oilseed used.(4)
Some of the traditional methods are still used in poorer parts of the world. Residents and visitors alike will tell you it’s as much for the taste as the lack of a cash economy. The story of making coconut oil in Bali is truly amazing. The process appears long and tedious, but it breaks down quite simply. Coconuts are grated and cooked, fats are skimmed from the surface and clarified, there’s more cooking and straining, and finally producing a small bottle of coconut oil, many tasty coconut-meat snacks, and no waste. The pictures are worth seeing.(5)
In India, Hindus have a hereditary profession called Kalu. Those born into this line of work are responsible for operating the ghani, which is a horse-powered expeller. The horse walks in a circle to turn the press. Traditionally this has been used to extract the oils from mustard, sesame, redi, and coconut for use by the village. Commercial extraction, and the spread of mechanized oil mills discussed above, have put many of these people out of work.(6)
Do-It-Yourself vegetable oil extraction
In my part of the world, coconuts do not grow. But sunflowers do. According to the research of Jeff Cox and friends at Organic Gardening, enough sunflower seed can be grown on 2,500 square feet to produce 3 gallons of sunflower oil. The first problem was dehulling the seeds which was accomplished with a grain mill set to crush the hulls of the largest seeds.
With each pass of unhulled seeds, they closed the mill’s teeth a little more. It took them about an hour to get 41 ounces of edible, whole seeds, losing little more than an ounce of seeds to breakage. This required a little ingenuity in figuring out how to quickly separate hull, seeds, and unhulled seeds
Making the press requires some welding, but it’s components are simple. A full description of this and directions to build your own press are available in the article.(7) It seems likely that this could be used to produce sesame and other seed-oils as well.
After much searching, I found an expeller for sale that has a price tag. Most expellers are not made for a household. They’re too big and cost thousands, if not tens of thousands, of dollars. This one however is made for the small gardener and reasonably priced around $150.(8)
Extracting your own vegetable oil looks both economical and practical. Those who have tasted the homemade version claim it has a much better aroma and taste than the store-bought versions. You can no doubt expect to see homemade vegetable oils for sale at farmer’s markets in the near future.