A matter of refinement: Swetha Sivakumar on cooking oils

The invention of refined oil in 1911 was a game-changer. It improved shelf life and increased the smoke point of oils, but at the cost of natural antioxidants and vitamins. How does one choose between traditional and refined options? Find out, in this week’s Sound Bites.

In 1911, Procter & Gamble released a path breaking new product: Crisco (for “crystallised cottonseed oil”). It was considered a marvel. How had the multinational company turned a dark, smelly by-product into a colourless, odourless in-demand food item? Cottonseed oil, after all, hadn’t even been considered fit to cook with in ancient times.

(Shutterstock)

Traditional unrefined oils include coconut, sesame, ghee and mustard oil in India, red palm fruit oil (called dende) in Africa, lard in China, tallow in the US, butter in Northern Europe and olive oil in the Mediterranean, but never cottonseed.

What P&G had done was invent refined oil. Refining removes impurities and unwanted elements, bleaches out the colours, and winterises or eliminates all waxes, among other things.

A key aspect of the process is alkali neutralisation, which eliminates free fatty acids (or FFAs). FFAs make oils taste soapy. Reducing these also improves an oil’s shelf life. Many vegetable oils, as a result, can last two years or more, unopened.

The refining process also increases the smoke point of oils. It strips away anything that is not a fat molecule, including water, pigments and vitamin compounds. These “impurities” burn at lower temperature than oils do. Stripping them away allows the oil to be used at higher temperatures, without burning or breaking down.

The smoke point of raw sunflower, safflower and canola oils, for instance, is only 107 degrees Celsius. Deep-frying can require temperatures of 200 degrees. Post-refining, the smoke points rise to at least 252, 266 and 204 degrees Celsius respectively.

Of course, this means that the oil loses many of its natural antioxidants, vitamins and other nutritional compounds. All that’s left is fat.

What does this mean when one compares the traditional and refined options? First, it’s important to know that there are three major dietary fats found in food: monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA) and saturated fats. (There is a fourth category, naturally occurring trans fats, but they only occur in very tiny amounts).

All oils contain a combination of the three major types. Coconut oil, for instance, is 89% saturated fat, and 11% MUFA and PUFA. Sunflower, safflower and cottonseed oils are PUFA-rich, and tend to go rancid quickly because PUFAs have a relatively unstable chemical structure. Oils rich in saturated fats (these include butters and ghee) are the most stable of the bunch, followed by MUFA-rich oils.

In trying to find a way to keep PUFA-rich oils from turning rancid within days of extraction, however, P&G hit upon a process that turned them into the most shelf-stable of them all. (Incidentally, MUFA-rich and saturated oils are now refined too, but that’s mainly to remove colour and aroma.)

Now, take a look back at those traditional oils. They seem like a diverse group, but they all have one thing in common: PUFA levels lower than 50%. These oils were chosen because they were the only ones that wouldn’t turn rancid in a few months. The fact that they need far less processing means that, today, they are the ones most likely to retain their original nutrients.

Should we bring back unrefined oils? I think there is a place for them in our kitchens. Many Italian home cooks take great pride in their traditional extra-virgin olive oil (EVOO). Bottles of it bear not just a “Best by” date (with a shelf life of up to 18 months) but also a “Harvested on” stamp, to indicate how fresh and preservative-free it is.

High-quality olives are selected, and processed minimally. And consumers around the world are willing to pay many times more for EVOO than for regular olive oil. Given India’s rich history of aromatic oils, cold-pressed oil producers here could take the same approach. Extra-virgin coconut oil? We need more of that.