Help! The Danger of burning oils and fats?

[FattyBoomBatty]

Hey everybody - FattyBoomBatty here!

I've been away from these boards (and this WOL) for nearly three years, and to make a long story short, I'm back!

But I had 3 years of catching up to do - so I spent some time on the Atkins website to re-educate myself. While doing so, I kept reading several warnings about not using "excessive heat" when cooking with olive oil!!! Doing so will transform saturated fat into trans fat!!

Now, this is a big red flag for me, because I rely heavily on stir frying on this WOL. And when I do, I put the flame on HIGH. The oil bubbles and pops, but doesn't necessarily burn.......

I was wondering if anybody here knew what exactly "extensive heat" means, what I should look out for when cooking, and any tips to avoid transforming my good fats into the evil trans fats!

Oh - also, does this excessive heat issue apply to all saturated fats? Like if I bbq a steak, and make it well done (not that I would), would I be turning its fat content into trans fats?

Thanks!
FattyBoomBatty

[mizski]

You want to use oils that are below smoking point for whatever you are cooking. A reasonable frying temperature would be 350 to 376 degrees. So, if a recipe's frying temperature for oil is 360°F, then refined oils like peanut oil, safflower oil, canola oil or grapeseed oil, which all have smoke points above 400°F are all good bets. Refined coconut oil also has a high smoke point. Here's a wiki list of cooking oils and their smoke points.

I use grapeseed oil a lot and also olive oil for sauteeing. For high heat stir frying, I would stick with peanut oil or if nut allergies are a problem go with grapeseed or canola.

But note that the longer an oil is heated, the more free fatty acids are formed, and the lower its smoke point will be. That is one reason oil should not be used for deep-frying or high-heat frying more than once. Another reason is that prolonged heating breaks apart unsaturated fatty acids and produces acrid and toxic compounds.

What this all means is that you want to keep your oil below the smoking point when cooking.

As far as the bbq'd steak, it is more of the burnt "crust" which some say has carcinogens rather than the fat which would drip out into the grill.

[FattyBoomBatty]

Thank you so much Mizski!! This is EXACTLY the kind of information I was looking for!

[Jarrod]

It is possible to degrade unsaturated fats into other (usually nasty-tasting) by-products via oxidation - i.e. heating in the presence of oxygen as you do when cooking. But you cannot form trans-fats by heating unsaturated oils such as olive oil on the stove or grill. Hydrogenation is a reductive process - the opposite of oxidation. Reduction requires a catalyst that can freely donate electrons (usually an easily-oxidized metal) and the presence of free hydrogen. These conditions are not present when you are cooking so I would not concern yourself with this.

Trans Fatty Acids are not Formed by Heating Vegetable Oils

[FattyBoomBatty]

Ahhhh - thanks Jarrod. That clears up some confusion. It's not the transformation into trans fats that is the problem, it's the degradation of the fats into by-products that I will avoid by staying below the smoking point.

Look at that...I learn something new everyday! Thanks for the article, it was an interesting read.