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.
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.
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?*|
|Rice Bran Oil||490°F/260°C||Yes|
|Light/Refined Olive Oil||465°F/240°C||Yes|
|Avocado Oil (Virgin)||375-400°F/190-205°C||No|
|Chicken Fat (Schmaltz)||375°F/190°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?
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.
- For Searing: With searing, the goal is to heat meat as rapidly as possible to promote browning. Choose a neutral fat with a high smoke point like peanut, corn, or vegetable oil, and heat it until it just starts smoking before adding your meat. Get our complete guide to pan-searing steaks and pan-searing pork chops at home »
- For Sautéing: You don't need smoking hot oil for a good sauté—virgin olive oil and other medium smoke point fats will do the trick just fine, so long as you keep a close eye on the stove. Heat a small amount of oil until shimmering or, at most, lightly smoking, and then add your ingredients, stirring as per recipe directions.
- For Deep-Frying: Your best bet with deep-frying is to always use a thermometer. Pick a high smoke point, neutral fat that can be heated at least 50°F above your intended frying temperature to account for temperature drops when ingredients are added. If you decide to use a more flavorful fat, like beef tallow or schmaltz, keep in mind that as it cools, that hot liquid fat will resolidify, leaving you with a waxy coating in your mouth. For more tips, see our full guide to deep frying at home »
- For Stir-Frying: Wok cooking is fast, and relies on a thin coating of smoking-hot oil to lubricate your food—the idea is to brown those ingredients and develop their flavor while retaining a crisp, fresh crunch. You'll want a really high smoke point oil, like peanut or safflower, for best (and safest) results. Get more stir-frying essentials and tips »
Next week, we'll be talking about saturation and when it does (and doesn't) matter!