How are Vegetable Oils Made?
Vegetable oil is everywhere! Most of us eat refined vegetable oils multiple times a day in various forms. It is in countless processed snacks, and we liberally pour it into our home cooking. I’ll admit there are about four different types of vegetable oils sitting in my kitchen right this minute.
But how much do we really know about vegetable oils?
In this article I’ll share with you:
- What is Vegetable Oil?
- How are Vegetable Oils made? (infographic)
- What is Vegetable Oil made out of? (ingredients, processing aids)
- History of Vegetable Oil
What is Vegetable Oil?
Refined vegetable oil is edible oil produced by a chemical process of extraction and refinement. They include oils made from palm, canola, soy, rice bran, olive and corn. Refined vegetable oils are also known as cooking oil, or simply vegetable oil.
In contrast to unrefined oils, refined vegetable oils are highly processed, resulting in an inexpensive, bland, light-coloured oil that is especially well-suited to frying. Palm oil can withstand higher cooking temperatures than most other oils, making it a common ingredient in processed foods.
Refined vs unrefined oil
The difference between refined vegetable oils and unrefined oils lies in the extraction process. Refined vegetable oils have been exposed to solvents to extract the oil from the oilseed. Unrefined oils are produced from fruit, seeds or nuts using mechanical extraction, such as grinding and pressing, without the aid of solvents. For example, one batch of olives may produce unrefined Extra Virgin Olive Oil in the first pressing, as well as refined oil by further treating the olive pulp with solvent.
Are vegetable oils bad for you?
Studies have shown that hexane used in refined vegetable oil processing can be hazardous to health. As well as cooking, refined vegetable oil is used in the manufacture of bio-fuels such as petroleum and diesel, and in making rubber, soap and detergent. Common by-products from vegetable oil production include soap and lecithin.
Refined oils are generally less healthy and less flavoursome than unrefined oils. Advantages to using refined vegetable oils over unrefined oils are their longer shelf life, lower cost and bland flavour suitable for cooking styles where the oil’s flavour is undesirable, such as deep frying.
How are Vegetable Oils made?
Processing vegetable oil is very complicated, so it no surprise there is some confusion about how vegetable oils are made. There are also many variations on the process for refining vegetable oil. Two common methods are alkali/chemical refining (shown in the infographic below) and physical refining.
While writing my non-fiction food comic book How Food is Made: An illustrated guide to how everyday food is produced (more about the book here) I researched a ton of food science and food industry books, magazines and journals to get the real answer to this question, which I give to you now.
The following is an extract from my book How Food is Made…
How are Vegetable Oils made infographic
What is Vegetable Oil made out of?
Vegetable Oil ingredients
- Oilseed eg soybean, corn
Vegetable Oil processing aids
Processing aids are additives that are used in the processing of a food, but are not present in the final food product in significant quantities. They may be present in the food in trace amounts.
- Solvent eg hexane
- Caustic Soda sodium hydroxide
- Acid eg citric,phosphoric
- Bleach eg clay, carbon
History of Vegetable Oil
Although edible oil has been produced and used for thousands of years, the process for refining vegetable oils is relatively new. Until processes for refining oil were developed, edible oils were unrefined, extracted by grinding and pressing. Over time, more sophisticated processes were developed for grinding and pressing, yet most of the oil still remained trapped in the fruit or nut. It is estimated that only about 10% of oils in a fruit or nut can be extracted by using grinding and pressing alone.
In the late 1800s, methods for using solvent to extract greater quantities of oil were developed. By using solvents such as benzene, producers could extract up to 98% of the oils present in a fruit or nut, making solvent extraction far more efficient than using only grinding and pressing.
In the early 1900s, refined cottonseed oil was being hydrogenated (hardened) to make shortening and was promoted as a substitute for lard. During the 1950s and 1960s in the USA, soybean oil was the cooking oil of choice. Later, in the 1970s and 1980s, canola oil made from rapeseed became popular, due to its lower saturated fat content, greater omega-3 fat content, and flavourlessness.
From the 1990s, palm oil gained huge popularity despite its controversial environmental impacts, as it yielded more oil per acre than other plants and could withstand very high cooking temperatures. Today, palm oil is the world’s most widely produced refined vegetable oil, and is used in a great many processed foods, cosmetics and biofuels.
Did you enjoy this article ‘How are Vegetable Oils made’?
If you’d like to learn more about the processed foods we eat everyday, please check out my non-fiction food comic book How Food is Made: An illustrated guide to how everyday food is produced. The book features 60 common foods, detailing their history and manufacturing process using illustrations and food infographics.
If you have ever wondered where factory food really comes from and how it is made, this book is for you. Don’t just take my word for it. The press and readers love the book too – check out media and reviews here. Find out more about the book here and view a free sample from the book here.
Thanks for reading!