What's in Chili Flakes, and Why Is the Heat So Uneven?

Chili flakes, also sold as crushed red pepper, are dried red chiles crushed with their seeds, most often cayenne-type peppers. They release heat in small bursts instead of spreading it evenly. A late pinch stays sharp and visible, while flakes warmed briefly in oil carry a rounder heat through the whole dish.

What are chili flakes made of?

The names on a jar tell you little about what is inside. American labels say crushed red pepper, British ones say chilli flakes, and neither name identifies the chile.

Most supermarket jars are built on cayenne-type peppers, often blended with two or three other varieties.

Blending lets a packer hold color and heat steady from whatever the harvest delivered, although heat still drifts from brand to brand.

Made from

Dried red chiles, usually cayenne-type, crushed with their seeds

Other names

Crushed red pepper, red pepper flakes, chilli flakes

Typical heat

About 30,000 to 50,000 Scoville heat units for a generic jar

Where the heat sits

The pale placenta and ribs inside the pod

Close relatives

Cayenne powder, Aleppo pepper, gochugaru

The pale seeds that make the jar look speckled are the least hot part of it.

Capsaicin is made in the placenta, the white tissue that holds the seeds, and a 2021 study of 21 chile cultivars found the most capsaicinoids there, then in the flesh, then in the seeds. Seeds taste hot mainly because they sat pressed against that tissue inside the pod.

"Chili flakes" is also a wider word than "crushed red pepper." Every jar of crushed red pepper is a chili flake, but the broader name also covers Korean gochugaru, Turkish pul biber and Italian peperoncino.

Powders cause a similar mix-up. British chilli powder is usually plain ground chile, while American chili powder is a milder blend with cumin, oregano and garlic.

The pizzeria shaker has a history too.

Southern Italians made crushed chile a common seasoning in the 19th century and carried the habit to the United States, where it became a fixture on pizza tables.

What do chili flakes taste like, and how hot are they?

Generic flakes taste mostly of dry heat, with a toasty red-pepper note and a nutty bitterness from the seeds. A fresh jar also smells faintly fruity, and that smell is the first thing to go as the flakes age.

On the Scoville scale, a generic jar lands in the same band as cayenne powder because it usually starts from the same peppers.

Spoon for spoon, flakes still taste milder. A teaspoon of flakes holds air between the pieces, so it carries less chile than a teaspoon of packed powder.

The heat also arrives in patches.

Each flake has to take up moisture before its capsaicin reaches your tongue. A bite that lands on a flake stings, and the next bite may miss one entirely.

That unevenness is the reason to reach for flakes over powder. Pizza, eggs and buttered noodles taste livelier with small bursts of heat than with the same heat spread evenly.

The bottom of a well-used jar behaves differently again. Broken seed and flake settle there as a fine dust, and that dust spreads through a dish like powder and scorches first in hot oil.

A very seedy jar tastes harsh for a related reason, since seeds add bitterness without adding much heat.

When should you add chili flakes?

Timing decides whether flakes act as a garnish or as a seasoning. A late pinch stays dry and visible, while flakes that cook in oil or liquid give their heat to everything around them.

The last row catches cooks out. A jar of pickles made with a generous spoonful can taste right on the first day and noticeably hotter a week later.

Long cooking does not boil the heat away either.

In a 2009 study, heating dried chile powder at 100 to 190°C (212 to 374°F) for 15 minutes cut its capsaicinoids by less than 10 percent. Only above that range did they break down quickly.

So a pot of chili that simmers for hours keeps its heat. The flakes soften and spread it, and the dish tastes rounder without tasting milder.

Drying has already developed the flavor of the flakes, which is why a finishing pinch needs no cooking to taste right. That is the same reason coarse finishing spices sit late in most spice timing advice.

Crushing flakes between your fingers before they go in helps the heat spread faster and more evenly.

Leaving them whole keeps the crunch and the red flecks that tell a diner where the heat is.

How do you bloom chili flakes without burning them?

Hot fat pulls color, aroma and heat out of flakes far faster than water does, because the capsaicin in chiles dissolves readily in fat and barely at all in water.

Dried flakes hold almost no moisture, so they go from fragrant to scorched in seconds. Scorched flakes taste bitter, and the bitterness spreads through all the oil in the pan.

The usual method for blooming spices in oil works here on a much shorter clock.

1. Warm the oilHeat the oil over medium-low until it moves loosely in the pan, well short of smoking.
2. Cook the garlic firstIf the dish uses garlic, let it turn pale gold before the flakes go in.
3. Add the flakes off the heatPull the pan from the burner and stir in the flakes so the leftover heat does the work.
4. Stop at orange-redOnce the oil turns orange-red and smells of toasted pepper, add the pasta, greens or liquid.

Garlic comes first because it needs longer than the flakes do. Many aglio e olio recipes add the pepper only as the garlic starts to color, so both finish at the same moment.

Watching the oil works better than timing it.

A pale spoon or a white bowl shows the color change clearly, while a dark pan hides it until the flakes have already darkened.

How many chili flakes should you add?

Published recipes for a pound of spaghetti aglio e olio, about four servings, typically call for 1/2 to 1 teaspoon of red pepper flakes. That amount gives clear warmth without drowning the garlic.

Penne arrabbiata is named for its "angry" heat, and America's Test Kitchen still uses only 1 teaspoon for a 28-ounce can of tomatoes and a pound of pasta.

A slice of pizza or a plate of eggs usually needs only a pinch, since flakes sitting on the surface hit the tongue directly.

Flakes keep releasing heat after they go in. A sauce can taste hotter a few minutes after seasoning, and leftovers often taste hotter the next day because the flakes spent the night soaking.

When a dish does come out too hot, the fix depends on what is carrying the heat.

Water does little for a burning mouth. Capsaicin barely dissolves in it, so a sip mostly moves the heat around.

For a mixed table, the pot can be seasoned for the most cautious eater, with flakes and chili oil passed separately. Anyone who wants more heat can then add it to their own plate.

That keeps one pot of sauce right for a child and for the person who likes it fierce.

Which named chili flakes are worth knowing?

A jar with a place name on it holds a specific pepper, dried in a specific way.

Several named flakes now turn up on ordinary shelves. The Korean, Syrian and Turkish ones are milder and fruitier than the generic jar, and the Italian and Thai ones match it or run hotter.

Gochugaru gives kimchi its red color. Its gentle heat lets a recipe use it by the tablespoon, and generic flakes at that volume would make the kimchi far hotter and speckled with seeds.

Aleppo pepper and Maras pepper both carry a little salt and oil from processing, which is why they clump instead of pouring.

Urfa biber turns a deep purple-black during its overnight sweating and tastes more of dried fruit and smoke than of heat.

A Turkish or Syrian recipe that asks for red pepper flakes usually means one of these milder flakes, not pizza-style crushed red pepper.

Calabrian flakes sit closest to the generic jar in heat. They suit the same pizza and pasta, with more fruit behind the burn.

Sichuan flakes are chosen for color and toasted aroma more than for heat.

Thai prik bon is a table seasoning. A small pot of it sits beside sugar, fish sauce and chile vinegar in Thai noodle shops, so each diner can make the broth as hot as they like.

Which chili flakes work best for homemade chili oil?

Chili oil is made by pouring hot oil over a bowl of flakes, which fries them for a moment and then steeps them as the oil cools.

Sichuan chili flakes are the usual choice for Chinese-style chili oil. They are coarse and bright red, and they give a toasted, fragrant oil more than a fierce one.

Generic crushed red pepper makes a poorer oil. The Woks of Life chili oil recipe warns against Italian-style red pepper flakes because the oil never turns deep red and the flavor falls flat.

The right oil temperature depends on how much moisture is left in the flakes.

The Mala Market's Sichuan chili oil recipe aims for about 300°F. All of these stay well below the 374°F point where capsaicinoids began to break down fast in the 2009 heating study.

Smell tells you more than the thermometer. Toasted chile smells nutty and warm, and a burnt smell means the batch will taste bitter all the way through.

Garlic, shallots or fresh ginger in the jar change how it must be kept.

Extension food-safety guides give the same warning for any fresh vegetable or herb in oil, including shallots and fresh ginger. A batch made only with dried flakes and dried spices is the safer kind to keep, because bacteria cannot grow without moisture.

What can you substitute for chili flakes?

Any substitute has to replace two things, heat and visible texture, and most replace only one.

Cayenne powder is the easiest swap in cooked dishes. The peppers are often the same, but powder packs tighter into a spoon and spreads through a sauce at once.

Aleppo pepper and gochugaru keep the flake while giving up most of the heat. On pizza or noodles that is often an improvement, since their fruit comes through where generic flakes give only heat.

Sweet paprika with a little cayenne is the fallback when color matters more than texture.

Paprika on its own adds color and sweetness but almost no heat. A finished pizza is where the powders fall shortest, because nothing replaces the visible red flecks.

How do you make chili flakes at home?

Homemade flakes let you pick the chile and the number of seeds, and those two choices change heat and bitterness more than anything else.

Thin-walled red chiles dry best, such as cayenne, chile de árbol and Thai chiles. Thick, fleshy peppers take far longer and can spoil before they are dry.

1. Protect your handsWear gloves, and glasses if you have them, while you cut and crush the chiles.
2. Cut to sizeSlice large chiles into pieces about 3/8 inch wide. Small chiles can be slit and left whole.
3. Dry them lowIn a dehydrator, start at 140°F for 2 hours, then drop to 130°F until the pieces are tough to brittle.
4. Toast for Thai-style flakesStir the dried chiles in a dry pan over low heat until they turn darker and shiny, never black, then let them cool.
5. Crush brieflyPulse or crush the chiles only until they break into flakes.
6. Sieve out loose seedsShake the flakes in a coarse sieve for a cleaner, less bitter result.

Short pulses matter because a spice grinder turns flakes into powder within seconds. Crushing in a sealed bag with a rolling pin is slower but gives more even pieces.

Air drying works only where the air is dry.

Penn State Extension notes that strung chiles can take 3 to 4 weeks, and high humidity can spoil them before they dry.

How do you buy and store chili flakes?

Color is the quickest freshness check. Fresh flakes are bright red, while brown or dull orange flakes have spent too long in light, warmth or air.

The heat outlasts almost everything else in the jar. Capsaicinoids break down slowly in dry storage, while the red pigments and the fruity smell fade much sooner.

That gap is why an old jar tastes harsh instead of weak, and adding more brings back heat and bitterness without the flavor.

• Bright red colorBrown or faded flakes have lost pigment and most of their aroma.
• A smell of dried pepperFresh flakes smell fruity and toasty when the jar opens, not dusty.
• Few loose seeds and little dustA jar that is mostly pale seeds and powder tastes harsher and scorches faster.
• A named pepperAleppo, Urfa or gochugaru on the label tells you what the flakes should taste like.
• A size you will finishA small jar used up quickly tastes better than a large one left to fade.

Flakes keep best under the same conditions as other ground spices, in an airtight jar away from the stove, sunlight and steam.

Clumping means different things in different jars. Aleppo pepper clumps because of its added oil, while clumps in dry generic flakes usually mean moisture got in, one of the signs a spice has gone bad.

Are chili flakes safe to eat without cooking?

Flakes are one of the few spices most people eat raw, shaken over pizza or eggs at the table. Any germs on them reach the plate without the heat of cooking.

That risk is real but small. In 2009 and 2010, a US Salmonella outbreak with 272 cases in 44 states and Washington, DC, was traced to black and red pepper coated onto salami after it was made.

A Brooklyn spice supplier recalled every 25-pound box of crushed red pepper it had sold to food makers over the previous nine months.

FDA testing of imported spice shipments from 2007 to 2009 found Salmonella in about 6.6 percent of them. A later FDA survey of spices on store shelves found much lower rates in 9 of the 11 types it tested.

The gap comes largely from processing, since responsible packers treat many spices to kill germs before retail sale.

The FDA has not advised people to change how they use spices. That makes a sealed jar from an established brand the practical safeguard for flakes eaten raw.

Those rules exist because the problem has turned up before. In 2005 a UK recall removed hundreds of foods made with a Worcestershire sauce that contained dyed chili powder.