Which cooking oils are best? It’s the eternal question facing cooks who shoot for both tasty and healthy cuisine. Then there’s which oil is best for the different cooking methods e.g., salad dressing, sauteing, or frying. Another issue involves the oil’s method of production. That’s a good place to start since you ideally want whatever oil you’re using to be free of impurities and easy on the digestive tract. Oils are not whole foods since they are extracted, therefore the method of extraction is important.

Different Types of Processing

A good general rule that applies to all cooking oils is that whatever the purpose they should be organic, cold pressed or expeller pressed, and unrefined. And what does that mean for the cook?

• Organic means that no chemicals or pesticides were sprayed onto the plants in the field.
• Cold-pressed or expeller-pressed means that oil-producing seeds were not heated while being crushed to release the oil.
• Unrefined means that chemicals were not added to the oil during its path from pressing to bottling. It’s important to remember that refining is a cosmetic procedure whose purpose is to make the oil clearer, paler, and odorless. It has no good effect on nutrition. Interestingly many organic oils are refined. In practical terms, this means that no chemicals were applied in the field but are present in the finished product having been added during refining.

Refining Oil

So what happens when oils are refined? The quick & dirty is as follows:

Seeds are picked, cleaned and steamed and then they are put into a press at high heat and crushed.

Next they are released into a hexane solution which gets rid of visible impurities, then put into a centrifuge with phosphate and spun. This causes the seed residue to separate from the oil which is then poured off.

So it helps to understand what hexane is and what it is is a food-grade petroleum solvent used in seed extracted oils. It’s been categorized by the EPA as a hazardous air pollutant when inhaled and due to its petroleum base it is volatile, flammable and explosive. If you do an internet search on cooking oil factory explosions you’ll find plenty to read.

Then the crude oil is “neutralized.” This is to render it flavorless. The oil is treated with caustic soda (sodium hydroxide) or soda ash (sodium carbonate). These make the oil paler & clearer but also more prone to rancidity.

The final procedure consists in bleaching. This is done with fuller’s earth or activated carbon & clay. The process makes the oil lighter but still more rancid. Then it is deodorized at 500 degrees or more.

Here’s an industry produced short video describing this process, emphasis on industry produced. It wasn’t made by food purist foodies but by canola oil believers. Judge for yourself whether you want to consume refined oils after you watch it because this is how they are all made.

And I can’t wrap this up without a discussion of the big kahuna of bad for you oils. Cottonseed oil. As a child I used to visit a relative in a rural area who lived near a gin that had a cottonseed oil operation nearby. You could always tell when they were pressing seeds because it smelled a little like God was up in the sky frying himself a chicken dinner. In short, it smelled pretty good. This is probably why some big chains use it.

Fast forward a couple of decades when I picked up a chicken bucket and several hours later it felt like a weather system was moving through my lower intestine. I knew it was what I had eaten earlier but didn’t realize that it was the oil until a friend pointed out that chicken shacks use cottonseed oil and that cotton is heavily sprayed. Eureka! She was right. Since cotton is not categorized as a food crop it has more pesticides than usual and it even has natural toxins which remain in small quantities. It’s cheap and is in everything so check other processed food labels for it.

What kinds of oils to use and where

If you’ve gotten this far you just want to know what to buy so let’s start with the easiest.

• Salad Dressing & Sauteing. Since salad dressing isn’t heated you just need to buy something you like that falls into the above-mentioned categories. Extra virgin olive oil, walnut, avocado, grapeseed, pecan & sesame oils (the untoasted kind) are all excellent and these oils are fine for light sauteing over medium heat.
• Frying. This is considered high heat so you want oils with higher smoke points. Oils stable over 350 degrees are clarified butter, peanut, coconut, palm, sesame and lard. When it comes to lard the only healthy kind is non-hydrogenated fat from hormone-free pigs. I get mine at the green market since I’ve never seen it for sale in a grocery store. (Update: It seems that Whole Foods now carries organic lard in glass jars.) The lard they have there is not recommended. For really high heat (over 500 degrees) you can use rice bran or avocado oils but be aware that they’re harder to find and expensive.
• Storage. Since oil is best stored in a cool dark place you want to buy from a store that has high turnover and the oil should be in a dark bottle. This is because most grocery stores have the lights on 24/7 which degrades the oil’s quality and a clear bottle exposes the oil to the light. Also check dates on bottles. If you’re buying some oddball expensive brand of specialty oil it’s probably best to go to a specialty store. Buying truffle oil at an edge of town superstore that caters to people who need five gallons of oil for frying turkeys means you’re probably getting old oil.

Finally, it’s important to remember that we need fat, it’s filling and it makes things taste good. It slows down digestion so that you can go longer without eating and it acts as a carrier for fat-soluble vitamins A, D, E, and K. Nobody should feel guilty about craving it or eating it, but a little knowledge before you purchase can make you feel better in mind and body.