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Ingredient Guide

A Guide To Chilli Peppers

25 April 2022

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Some like it hot: Discover all there is to know about the different varieties of chilli peppers.

What are chilli peppers?

Chilli peppers are the fruits of Capsicum pepper plants, which belong to the nightshade family, along with tomatoes and eggplants. They burn our tongues, make us sweat and bring tears to our eyes, but they’re still eaten by a quarter of the earth’s population every single day in countries across the globe.

Native to tropical South America, chillis are widely cultivated in warm climates around the world and vary greatly in colour, size, heat and flavour. There are approximately 4,000 varieties of chillies and their main purpose is to turn up the heat and add flavour and depth to a variety of dishes, mainly curries, stews and stir-fries. But they can also be used to cut through the richness of chocolate, infuse heat to marinades and dry rubs, liven up a salad and add spice to eggs, jam, sauces and even cocktails.

Why are chillies called chillies?

The term chilli refers to the spicy fruit of the Capsicum plant, which is commonly used in cooking to add flavour and heat to dishes. The origin of the term “chilli” is somewhat unclear, but it is believed to have come from the Nahuatl language, which is spoken by the Aztecs and other indigenous peoples of Mexico.

In Nahuatl, the word “chilli” (also spelt “chile” or “chil”) referred specifically to the Capsicum fruit, and it was used as a loanword in Spanish and other European languages when chilli peppers were introduced to those cultures.

Why are chillies hot?

The burning sensation you feel in your mouth after eating chillies comes from capsaicin, a compound found within almost every pepper. It activates a protein called TRPV1 – whose job is to detect heat and alert your body when something on your skin is too hot.

Many people reach for a glass of water to try and lessen the burn, but it simply spreads the fiery chemical around their mouth and makes it even worse. That’s why people are best off drinking a glass of milk or eating ice cream, or another dairy product like yoghurt. Containing casein, they remove capsaicin from your flaming tongue.

All hail the chilli pepper

National Chilli Day is celebrated every year on the fourth Thursday in February and pays homage to the legendary plant that brings joy and tears to chilli lovers across the globe.

What is the Scoville scale?

Chillies are measured using the Scoville scale, which is a measurement of the level of capsaicin in spicy foods. The scale was named after its creator, American pharmacist Wilbur Scoville, who devised the method in 1912.

Capsaicin stimulates the nerve endings in the mouth and throat, which sends a message to the brain that the body is experiencing heat. The sensation can range from a mild warmth to a burning sensation depending on the amount of capsaicin present.

types of chilli plants

What is the unit of chilli heat?

The Scoville scale is quoted in Scoville Heat Units (SHUs). The scale ranges from 0 (no heat) to over 2 million Scoville heat units (SHU) for the hottest peppers. While bell peppers score zero on the Scoville scale, jalapeños can reach up to 8,000 SHUs, with scotch bonnets up to 40 times hotter with a scorching heat rating of 100,000 to 350,000 SHUs, and the Ghost Pepper has a rating of around 800,000 to 1,000,000 SHU.

The Scoville scale works by measuring the dilution of capsaicin extract needed to reach a point where the spiciness is no longer detectable to a panel of taste testers. The pepper is allocated a number (SHU) based on how much sugar water is needed to neutralise the heat from an extract of its capsaicin oil.

What is the hottest pepper on the Scoville scale?

A contestant in a 2016 chilli-eating contest in New York ate a Carolina Reaper (the world’s hottest chilli in the world measuring over two million SHUs) and was subsequently hospitalised with ‘thunderclap’ headaches.

10 types of chilli peppers and how to cook with them

With thousands of different varieties of chilli peppers around the world, we can’t possibly talk you through each one. Instead, here’s a list of chillies by heat (from mild to hot hot hot) and how to cook with each one.

Bell pepper

SHUs: 0

The supermarket bell pepper (or sweet pepper) has a Scoville rating of zero, so you can eat it safely with no risk of burning your tongue. They’re native to Central and South America, although China is the world’s largest producer and distributor.

Available all year round, the most common bell peppers found in supermarkets are green, yellow, orange, and red. All bell peppers start out green and change colour as they ripen. Yellow, orange, and red bell peppers are sweeter and less bitter than green ones.

Sweet and mild in flavour, bell peppers are eaten raw, sautéed, roasted or stuffed and are used in many different cuisines around the world. They make a delicious side dish on their own, and also a wonderful addition to fajitas, dips, soups, pastas and pizzas. Plus, they’re healthy too – a raw bell pepper provides approximately 97% of your recommended daily intake of vitamin C.

Banana pepper

SHUs: 1-500

Banana peppers, also known as wax peppers or banana chillies are native to South America, although they’re now grown around the world including India, China, the United States and Europe.

Banana peppers thrive in any warm climate and have a mild, tangy flavour. Given its name, there’s no surprise that these medium-sized peppers are bright yellow in colour, but they can turn green, red or orange as they ripen. Yellow banana peppers are the mildest and red banana peppers are the most mature and therefore the spiciest, but also a lot juicier than their green, yellow and orange counterparts.

Banana peppers also taste slightly sweet, which makes them a popular topping on pizzas, and they’re also delicious stuffed with meat and cheese. They also add a crunch to recipes when used raw, like in Greek salads, sandwiches and salsas. You can pickle them too, which enhances their natural tanginess and adds acidity and subtle heat to any dish. You’ll quite often find pickled banana peppers in sandwiches, tacos and nachos.

Anaheim pepper

SHUs: 500-2,500

Although named after its city of origin, Anaheim in California, you’ll also find this long, mild, chilli used frequently in Mexican cuisine. Other names for the anaheim pepper include California peppers, New Mexico peppers, Magdalena, and as a dried chilli known as chile seco del norte.

New Mexico varieties tend to be a lot hotter than those grown in California, ranging from 250 to 10,000 SHUs and are commonly used in cooking to add heat, without blowing your head off. When used raw, they are bright and refreshing with a sharp spice, making them the perfect addition to cocktails.

Due to their thicker flesh, they’re also perfect for roasting, where they develop a subtle sweetness. Stuffed Anaheim Peppers with ground beef and cheese are a popular Mexican-flavoured dish, offering just a little bit of heat and loads of flavour. They’re also a good pepper of choice for building flavour into dishes like soups, stews and sauces and are often used to make fresh salsa.


SHUs: 2,500-8,000

Originating from Mexico, Jalapeños are one of the world’s most popular and versatile chilli peppers, giving a noticeable kick to any dish. You’ll find them in Tex-Mex cuisine, Thai recipes, Spanish foods and more.

They’re typically picked and eaten when they are still green in colour and not totally ripe, giving them a somewhat grassy, bitter flavour. Harvested red, they’re slightly sweeter and hotter. Once smoked and dried they are called chipotle peppers, which can be ground into chilli flakes or powders to use as a dry rub on meats, or seasoning in chillis and sauces.

Jalapeño peppers are widely used in tomato salsa, guacamole and other Mexican dishes like quesadillas, burritos, enchiladas and tacos. And they can be enjoyed in a variety of different ways from raw to roasted.

Cayenne pepper

SHUs: 30,000-50,000

Known for their bold red hue and fiery taste, cayenne peppers are said to originate from the Cayenne region of French Guiana, located on the north tip of South America. But despite their spicy flavour, cayenne peppers have a deceptively mild aroma.

Green to red in colour, they’re widely used in Mexican and Indian cuisines to bring intense heat to a dish. Cayenne peppers are generally dried and ground to make the powdered spice of the same name, which is how it’s most commonly used in the UK, but some cuisines use them whole.

In Mexico, cayenne peppers are used in everyday cooking to flavour sauces, meat marinades and well known dishes like enchiladas and fajitas. While in Asian cuisine, it’s commonly used in curries and spicy Thai soups. You’ll also find them as a centrepiece on nearly every pizzeria’s table.

Piri piri or Peri peri

SHUs: 50,000-100,000

When you see the words ‘piri piri’ you may instantly think of Nandos, which, for those of you who aren’t aware, is a massively popular multinational South African fast food chain that specialises in flame-grilled piri piri style chicken. Piri Piri, peri-peri, pili pili, African bird’s eye chilli, or whatever you want to call it, simply means ‘pepper pepper’ in Swahili, but don’t be deceived by the name. Although it can be relatively mild, the piri piri chilli can pack plenty of heat, easily reaching up to 100,000 on the scoville scale.

It originated from the Americas, was brought over to Spain and Portugal, and its popularity has quickly spread worldwide. In terms of flavour, piri piri sauce is sour, slightly sweet and salty, making it a truly versatile condiment that can be used on almost anything – from marinating shrimp before grilling to brushing on roasted chicken just before the end of cooking, and mixing with mayonnaise for a deliciously spicy dressing to spread on to your sandwiches. It also pairs exceptionally well with burgers, wraps and skewers, making it a must-have condiment for barbeques.

Piri piri features heavily in African and Portuguese cuisine where it’s often used in a marinade on chicken and fish, alongside a number of other ingredients, including garlic, basil, onions, olive oil, lemon, oregano, bay leaves, tarragon, paprika and orange zest. Piri Piri chicken is one of Portugal’s most famous dishes where whole chickens are spatchcocked (removing the chicken’s backbone so that it lays flat), marinated and served alongside fries and/or rice, and salad.

Scotch bonnet

SHUs: 100,000-350,000

Ranging from 100,000 to 3,500 scoville heat units, even the mildest Scotch Bonnet is over 12 times hotter than the spiciest jalapeño. That’s why in Guyana it’s called ‘Ball of Fire.’ It’s native to the Caribbean, but is now grown in parts of Africa, Florida and South America.

If you can handle the heat, these peppers are actually very fruity and somewhat sweet, livening up everything else on the plate. Scotch Bonnet is a key ingredient in many of the Caribbean’s best loved dishes, including curry goat, jerk chicken and escovitch fish.

Jamaican scotch bonnet recipes make some of the tastiest hot pepper sauces to season chicken, fish and meat. It’s also widely used to make salsas, hot ketchup, pepper jams and pickles.

hot red chilly peppers

Bhut jolokia or Ghost pepper

SHUs: 855,000-1,041,427

Bhut jolokia, also known as ‘ghost pepper’, is one of the hottest chilli peppers in the world. It’s native to Assam in India, usually red in colour (although you can get other varieties) and is twice as hot as the red savina habanero (which held the crown of the world’s hottest chilli from 1994 until 2006).

If you think a jalapeño is hot, then don’t go near a bhut jolokia. These chillis have a slow-burning heat, which doesn’t kick in for about 30 seconds. When the heat hits, expect to sweat, your eyes to water and you might even experience hiccups. But if you can handle it, these chillies do offer an intense fruity, sweet flavour, making them the perfect ingredient for tomato chilli recipes and (very) hot spicy soups. In fact, some of the most popular hot sauces in the world feature this scorching chilli as its star ingredient.

It’s also used in a number of Indian, Mexican and Tex-Mex dishes to add intense heat. In India, bhut jolokia is also used as a homoeopathic remedy for stomach pain and as a way to survive in the intense heat – because when you eat it, you’re going to sweat, sweat, sweat, which will help to lower your body temperature. A word of caution: if handling bhut jolokia, where gloves – no one wants a ghost pepper in their eye.

Did you know? Bhut jolokia is pretty lethal. Locals in northeast India smear their fences with it to keep elephants away and it’s also been used in smoke bombs. A 47-year-old American man who chowed down on a hamburger smothered in bhut jolokia was left with a two-and-a-half centimetre hole in his oesophagus and had to undergo emergency surgery.

Naga morich


The Naga Morich, also known as ‘snake’ or ‘serpent chilli’, is closely related to the bhut jolokia and comes from northeast India and Bangladesh. Reaching up to 1.5 million SHUs, it’s one of the hottest chilli peppers in the world – 300 times hotter than the average jalapeño.

It’s particularly aromatic, with tropical fruit and floral notes, slightly smoky and sweet, and of course, spicy. Like the bhut jolokia, the naga morich’s fire slowly intensifies after eating, and is a great addition to marinades and hot sauces. It can also be ground into a super-hot chilli powder. In Bangladesh, they tend to eat naga morich raw and it’s often offered as a whole fruit, which they can break pieces off of as an accompaniment to rice and other dishes.

Due to the intense heat and venomous bite of this fiery chilli, use sparingly – just a pinch is plenty enough to pack a punch to soups and stews. It also pairs very well with meat, so if you really want to crank up the heat in your cooking, try it in your next chicken or beef curry.

Carolina reaper

SHUs: 1.4-2.2 MILLION

The Carolina Reaper has been the Guinness World Records’ official hottest pepper since November 2013 and is 400 times spicier than a typical jalapeño.

It was first cultivated by Ed Currie of the PuckerButt Pepper Company back in 2004, crossing a Naga pepper from Pakistan with a habanero pepper from the Caribbean island of St Vincent, and although it’s excruciatingly hot, it has a real fruitiness to it. If you dare to try it, you’ll certainly feel the burn. The first time Ed Currie tasted the golf-ball-sized chilli he said it knocked him to his knees.

Take an initial bite and the Caroline Reaper tastes unexpectedly sweet. But then the heat really kicks in and in Currie’s words: “it’s kind of like eating molten lava,” before the heat slowly disappears some half an hour later. So if you’re a chilli addict who loves the burn, try out the Carolina Reaper in your next hot sauce recipe.

These ridiculously hot chillies can be canned and dehydrated into powder or flakes, which are used to spice up soups, stews and, of course, chillies. You can also use a very tiny amount as a dry rub for barbecued meats.

Do chilli peppers have any health benefits?

Some chillies may cause a lot of pain and tears, but they also offer a number of unexpected health benefits to spice up your diet. They’re particularly rich in vitamins, specifically A and C, making them powerful immunity boosters. To put this into perspective, chilli peppers contain about 107 mg of Vitamin C – an orange contains approximately 69mg. And they contain more than 77,000 units of Vitamin A, which is about 15 times the minimum daily requirement.

The capsaicin found within chilli peppers also helps to unblock your sinuses, helping to relieve congestion, which is why a lot of people eat curries when trying to fight off cold and flu symptoms. Capsaicin also aids the circulatory system and prevents heart disease by lowering cholesterol. It also increases your metabolism, burning more calories. So if you’re trying to lose weight, try adding some extra chilli peppers to your diet.

Research has also shown that large consumption of peppers can be effective against breast, pancreatic and bladder cancers

green chillies Scoville scale

How to handle chillies

If you’re sensitive to capsaicin, it’s always best to wear a pair of rubber or latex gloves when handling chillies. You can also rub a little oil on your hands before handling the peppers, as this can help to reduce the heat and prevent the capsaicin from sticking to your skin. Avoid touching your eyes and nose, as this could result in severe irritation depending on the heat level of the chilli you’re cooking with. If you do get some in your eyes, soak a cotton pad or ball in cold milk and apply it as a compress.

Oils from chillies can also transfer to cooking utensils and chopping boards, so wash them thoroughly in hot, soapy water after use, and also wash your hands – the heat from chillies can stay on your skin for hours, even after a good scrub.

How to prepare and cut chillies

Before you start cutting the peppers, it’s important to wash them thoroughly. Rinse them under running water to remove any dirt or debris. This will help to prevent any bacteria or other contaminants from getting onto your knife or cutting board.

Start by cutting off the stem of the pepper. This will make it easier to cut the rest of the pepper and remove the seeds. Next, cut the pepper in half lengthwise. Use a sharp knife to make a clean cut through the flesh of the pepper.

If your recipe asks you to seed the chilli pepper, simply scrape away the veins and seeds with a spoon or the tip of the knife. A sharp, sturdy knife will make the job easier and a serrated knife can be useful for cutting through the tough skin of some peppers. A melon baller is also a great tool for deseeding chilli peppers, removing the membrane and seeds in one swift motion. Be sure to remove as much of the membrane as possible, as this is where a lot of the heat is stored.

If you prefer a hotter chilli, feel free to leave the seeds and membrane as they are.

To cut chilli peppers into strips, slice lengthways with a sharp knife while keeping the chilli skin-side down. To finely dice, bunch the sliced strips together and cut across them widthways.

Be careful not to touch your eyes or face while you work.