I’ll address some of the responses to last week’s post on canola oil at a later date, so stay tuned. But first, I want to address a query from reader Arvind Gaikwad because it’s so basic to any discussion about cooking fats. For starters, it gives me a chance to suggest a couple of books that you may well want to add to your library. Plus, it gives me a chance to torpedo one more culinary myth (it’s at the very end, for all you cut-to-the-chasers). “What is trans-fat?” Arvind asks.
One of the simplest explanations of trans fatty acids comes from On Food and Cooking: The Science and Lore of the Kitchen, by Harold McGee. “Trans fatty acids are unsaturated fatty acids that nevertheless behave more like saturated fatty acids,” he writes. In other words, just like the saturated fats in meat, butter, and cheese, for instance, trans fats raise your “bad” cholesterol (LDL). They also complicate matters by simultaneously lowering your “good” cholesterol (HDL). Trans fat molecules are pesky little things; they hang around in your body’s arteries, just waiting to give your heart the what for. They also trigger inflammation, which is implicated in a host of chronic diseases and conditions.
Here’s something you may not know: The dairy products and/or meat fat from ruminant animals such as cows, bison, sheep, goats, and deer contain small amounts of natural trans fats. Raw, pasteurized, organic, grass-fed, corn-fed, whatever—it doesn’t matter. Made by microbes present in the animals’ stomach, naturally occurring trans fats aren’t considered harmful, according to much of the current research, but the science is still inconclusive.
On the other hand, industrially created trans fats, a product of hydrogenation—heating liquid vegetable oils in the presence of hydrogen gas and a catalyst—are just terrible for you. In fact, they pose a greater threat of heart disease than saturated fats.
And, if you eat lots of processed food, they are everywhere. Why? A partially hydrogenated vegetable oil converts a liquid fat, like oil, into a solid fat, like margarine. In fact, the partially hydrogenated fats in margarine, since they came from vegetable oil, were once considered better for your health than butter, with its cholesterol and saturated fat.
Industrially produced trans fats also helped put the convenience into convenience foods. Partially hydrogenated fats are very stable—they don’t turn rancid easily or quickly, so food manufacturers started to use them in products for longer shelf life. That stability also means that partially hydrogenated oils can also be repeatedly heated without breaking down, which makes them very cost-effective for restaurants and the fast-food industry.
It sounds like many of you out there view supermarket aisles with a deservedly suspicious (if not downright paranoiac) eye. But let’s face it: There are times when you may give into a stress-related craving. Impossible deadlines! Your neighbor, who plays nothing but those Andean flute music CDs! Finals! Graduating and moving back in with your parents because all you can find is some stupid internship that pays nothing, and you haven’t told Mom you have a pet boa constrictor!
Just so you know, here’s a quick cheat sheet of some processed foods that likely contain trans fats. You can avoid them or say to hell with it and indulge. Just this once.
- fast food—including fried chicken, biscuits [drat!], fried fish sandwiches, French fries, sweets like fried pies
- muffins, cupcakes, doughnuts
- crackers, chips, cookies
- cake and other baked goods with frosting
- microwave popcorn
- canned biscuits
- non-dairy creamers
Now, if you’re a diligent label reader, you do not know what to think when the nutrition label says “Trans Fats 0,” but partially hydrogenated vegetable oil appears in the ingredients list. According to the instant classic What to Eat: An Aisle to Aisle Guide to Savvy Food Choices and Good Eating, by Marion Nestle, this signifies the amount of trans fats present in the food is less than half a gram per serving. Again, if you don’t eat lots of processed food, I wouldn’t worry, but if you do, be aware that all those half grams in all those (teensy) servings can add up fast.
Okay, let’s move into your kitchen for just a sec.
In the wider online culinary community, one statement that’s slung about with great certainty is that when cooking oils like canola or olive reach their smoke point (the stage at which heated fat begins to smoke and emit an acrid smell and off flavor), trans fats are created. That is not true. I double-checked with Marion Nestle to make sure. “Trans fat requires hydrogenation, which takes a lot more than heat. Forget that one,” she shot back.
So this is one more thing you do not have to worry about! Hydrogenation involves temperature, time, and pressure, and you cannot accidentally hydrogenate an oil simply because you left the stove to answer the phone. It was your mother, remember? The boa constrictor arrived.
Be honest: Do you crave a Twinkie now and then? Do you cheat and eat trans-fat foods once in a while?