A Hamburger Today

Cooking Fats 101: What's a Smoke Point and Why Does it Matter?

[Photograph: Shutterstock.com]

Getting to know your fats can be a slippery business. If wading through the myriad bottles on supermarket shelves wasn't already a daunting task, then the latest word on saturated fats is enough to turn everything on its head. In this series, we'll be talking about what makes fats special, how to tell them apart, and how to pick the best one for the job.

Last week, we talked about what makes fats and oils essential to cooking. But what about the factors that set them apart? One of the most important things you'll want to consider when picking out a fat is smoke point.

But what is a smoke point, and why does it matter?

Ever left oil in a pan over high heat, only to turn around and find it billowing with smoke? That's because every cooking fat, be it butter, lard, or oil, has a smoke point: a temperature at which it stops shimmering and starts sending out some serious smoke signals. Learning how to interpret those signals is a crucial element of any good cook's vocabulary.

20140513-deep-frying-smoke-point.jpg

[Photograph: J. Kenji Lopez-Alt]

To understand how smoke points affect food, we have to look to where our fats come from and how they've been processed. Traditionally, oils are extracted from nuts and seeds through mechanical crushing and pressing. If bottled immediately thereafter, you've got a cold-pressed raw, or "virgin" oil, which tends to retain its natural flavor and color. Many unrefined oils are packed with minerals, enzymes, and other compounds that don't play well with heat and tend to be especially susceptible to rancidity; these are the oils best-suited to drizzling, dressings, and lower temperature cooking.

To produce an oil with a high smoke point, manufacturers use industrial-level refinement processes like bleaching, filtering, and high-temperature heating to extract and eliminate those extraneous compounds. What you're left with is a neutral-flavored oil with a longer shelf life and a higher smoke point. Clarified butter, or ghee, follows the same basic concept: a process designed to extract more heat-sensitive components—in this case, milk solids—from a fat in order to raise its smoke point.

Now, when it comes to actually cooking with fats, smoking oil isn't always a bad thing—oftentimes, you'll want that wok or skillet ripping hot. But when a flavorful, raw oil or pool of butter starts sending up smoke, you're headed into a danger zone. Sure, smoke is pesky, but that's not why you should be concerned. Heated past its smoke point, that fat starts to break down, releasing free radicals and a substance called acrolein, the chemical that gives burnt foods their acrid flavor and aroma. Think watering eyes, a stinky kitchen, and bitter, scorched food.

20140428-free-radicals.jpg

Free Radicals [Illustration: Niki Achitoff-Gray]

Another side effect of that breakdown? As a fat degrades, it's also getting closer to its flash point, producing ignitable gases that you probably don't want hovering over an open flame. That said, if your oil starts to smoke, don't panic. You're almost definitely not about to spontaneously combust. But unless you're using a high-smoke point, neutral fat, you'll at least want to take it off the heat. And if it's a flavorful oil, give it a sniff and a taste once it's cooled; if it's started to develop any unpalatable flavors, just pour it into a disposable container and replace it with a new batch.

The moral of the story? The higher a fat's smoke point, the more cooking methods you can use it for. But even if you've taken the care to purchase a high-smoke point oil, there are a few things you'll need to watch out for.

Light, heat, water, and air are the sworn enemies of cooking oils. While adding some used oil to a fresh batch can actually improve browning, you'll want to exercise care—hitting a smoke point further lowers that smoke point, so if your deep-frying fat has been smoking, you won't be able to successfully reuse it as many times. Most flavorful oils that don't get used rapidly, like avocado, hazelnut, sesame, and walnut oils, should be refrigerated. And no matter the oil's starting smoke point, you do NOT want to store it over the stove—the extra heat can lead to rapid rancidity.

Keep your oils tightly sealed in a cool, dark place and, if they come in a translucent bottle, consider wrapping them in tin foil to extend their shelf life.

Smoke Point Index

Here's a handy chart of the smoke points of common fats; it's the list I was handed when I was in culinary school, courtesy of the latest edition of the Culinary Institute of America bible, The Professional Chef, with some gaps filled in by my personal bible, Modernist Cuisine.

Type of Fat Smoke Point Neutral?*
Safflower Oil 510°F/265°C Yes
Rice Bran Oil 490°F/260°C Yes
Light/Refined Olive Oil 465°F/240°C Yes
Soybean Oil 450°F/230°C Yes
Peanut Oil 450°F/230°C Yes
Clarified Butter 450°F/230°C No
Corn Oil 450°F/230°C Yes
Sunflower Oil 440°F/225°C Yes
Vegetable Oil 400-450°F/205-230°C Yes
Beef Tallow 400°F/250°C No
Canola Oil 400°F/205°C Yes
Grapeseed Oil 390°F/195°C Yes
Lard 370°F/185°C No
Avocado Oil (Virgin) 375-400°F/190-205°C No
Chicken Fat (Schmaltz) 375°F/190°C No
Duck Fat 375°F/190°C No
Vegetable Shortening 360°F/180°C Yes
Sesame Oil 350-410°F/175-210°C No
Butter 350°F/175°C No
Coconut Oil 350°F/175°C No
Extra-Virgin Olive Oil 325-375°F/165-190°C No

*All neutral oils listed on this chart are refined; though unrefined versions of them do exist, these are the varieties most common to a home cook's repertoire. Meanwhile, the majority of flavorful oils are expeller-pressed and, though available refined, are often quite costly and uncommon.

So when do I pull out the big guns?

Flip Frequently

[Photograph: J. Kenji Lopez-Alt]

You'll want to make sure you're using fats with smoke points at or above 400°F when you're cooking at high temperatures.

Next week, we'll be talking about saturation and when it does (and doesn't) matter!

Printed from http://www.seriouseats.com/2014/05/cooking-fats-101-whats-a-smoke-point-and-why-does-it-matter.html

© Serious Eats