Are peppers, green onions, and onions the same kind of spicy? The answer is...

Many people in life cannot live without spicy food. When it comes to "spicy", I guess everyone will think of the spicy taste brought by peppers. In fact, spicy ingredients are not limited to peppers. Spicy food is also a large family. Different foods can bring us different "spicy experiences".

This article will talk about 8 different ingredients. Although they are spicy, they can make us taste different flavors. Let’s see which one you like the spiciest?

Capsaicin, the spicy ingredient in chili peppers

Chili is not only a vegetable but also a spice. The fruit is hollow and filled with a white spongy substance, also called the placenta.

The spicy chemical in chili peppers is capsaicin, which is synthesized by cells on the surface of the chili placenta and then stored in droplets in the keratin layer just below the surface of the placenta. [1] Therefore, the spongy placenta and the white tendons extending from it are the hottest parts of chili peppers. If you cannot tolerate spicy food, removing the placenta and white tendons when cooking can greatly reduce the spiciness.

Although capsaicin tastes spicy and causes burning and stinging sensations, recent studies have shown that capsaicin has potential cardioprotective and anti-tumor effects [2] and may also help control blood pressure. Eating spicy food in moderation can also improve metabolism and aid weight loss. Eating spicy food can also improve cognitive ability and cerebrovascular function [3].

But if you can't stand spicy food, don't force yourself to eat it. Eating too much spicy food can also cause a lot of discomfort, such as diarrhea, stomach pain, aggravated acne, aggravated anorectal diseases, etc.

The spicy taste of green onions - sulfide

Scallions are an important condiment in the kitchen. They can add fragrance, remove fishy smells, and give dishes a unique flavor. They are essential for cooking every dish. Although scallions used for cooking are not spicy, if you eat scallions raw, especially the white part, it will be very spicy. The spiciness of scallions comes from its unique sulfides. The most abundant sulfur-containing compounds are S-propylmethane thiosulfonate, dipropyl trisulfide, and dithiomethan, [4] which have a strong spicy and pungent taste. In addition, the content of spicy substances in the white part is higher than that in the leaves, so it tastes spicier.

However, after the green onions are heated, the cooking oil can react chemically with the green onion matrix under high temperature conditions to produce a large amount of flavor substances, which can effectively alleviate its spicy irritation and give it a certain salty and roasted aroma.

Therefore, onion leaves can be used in cold dishes, and onion whites can be used in stir-fried dishes.

The spiciness of onions - sulfide

Onions are the tear gas in the kitchen. They come with a built-in sentimental buff. Every time I cut onions, I can't help but burst into tears. I continue cooking with a handful of bitter tears. The pungent smell of onions comes from dipropyl disulfide and other disulfide and trisulfide compounds. Dipropyl disulfide and dipropyl trisulfide are the main volatile substances in fresh onions. [4] Cutting or chewing will cause volatile substances to overflow, drift into our eyes and noses with the air, and invade nerve endings. When they come into contact with the eyes, they will stimulate the free nerve endings on the cornea and stimulate the lacrimal glands to secrete tears. [1] This will make us cry. Green onions also have a similar phenomenon.

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It is precisely because of the presence of organic sulfides that onions taste spicy. However, cooking and heating will cause the characteristic flavor of onions to decay and lose its spiciness. When cutting onions, you can soak the onions in cold water for 30 to 60 minutes, [1] or refrigerate them for half an hour, or cut them directly in water, or wear goggles when cutting them, all of which can reduce the irritation to the eyes caused by cutting onions.

Garlic's spicy taste - allicin

Garlic is not only a condiment in the kitchen, but also has many labels such as "antibacterial, anti-aging, disease prevention, lipid-lowering, and anti-tumor".

The reason why garlic is given these labels is because of the allicin in garlic, which is also responsible for its spicy taste. When garlic is squeezed or cut, the alliin in garlic will quickly generate spicy and irritating allicin under the action of alliinase, which is further converted into other volatile sulfur-containing compounds, such as dimethyl disulfide and dimethyl trisulfide. [4] Allicin is not only the biologically active substance in garlic, but also the main ingredient for seasoning dishes.

However, allicin is afraid of heat, and its activity will be lost when heated, so it will not taste spicy. For example, when cooking or making soup, throwing a few cloves of garlic into the pot will not only not feel spicy, but also be beneficial to intestinal health.

The spiciness of leeks - sulfide

Leek is a vegetable with a unique flavor, especially when used to make leek dumplings, which are very delicious. Leeks are rich in volatile substances, and contain a wide variety of sulfur compounds with high content, which are the main source of the aroma and flavor of fresh leeks. Leeks taste slightly spicy because they contain sulfide compounds such as dimethyl trisulfide, dimethyl disulfide, methyl propylene disulfide, and methyl allyl trisulfide, which give leeks a spicy aroma of onion and garlic. [4] Raw leeks have a strong spicy taste, but the spicy taste of fried leeks will decrease, and the aldehydes in them will give them a strong fried taste and grassy aroma.

The spicy taste of ginger - gingerol

Ginger is a common spice in the kitchen. It is indispensable for adding flavor to dishes, removing fishy and muttony smells, and adding flavor. Cooking with it is naturally delicious, but if you soak it in water or eat it directly, many people will find it "spicy". The spiciness of ginger comes from gingerols, which is a general term for gingerols, shogaols, gingerolone and other spicy substances related to ginger. Dried ginger is spicier than fresh ginger because gingerols can be dehydrated and converted into shogaols under dry conditions. Shogaols are spicier, about twice as spicier as gingerols. Cooking reduces the spiciness of ginger because shogaols are converted into shogaols when heated. Shogaols are less spicy and have a sweet taste. [1]

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Therefore, adding a few slices of ginger when stewing soup will not only make the soup flavorful, but the ginger slices will not taste very spicy.

The spicy taste of horseradish - isothiocyanates

The toothpaste-like green wasabi (horseradish sauce) is a seasoning for many special side dishes. It has a spicy and pungent taste, and many people cannot resist this pungent pleasure. Horseradish is its main ingredient. Horseradish is a cabbage plant native to West Asia. Isothiocyanate is the main bioactive ingredient in cruciferous plants such as horseradish and mustard, which have a spicy and stimulating taste. [1] In fact, the whole cruciferous plant is not spicy. When it is processed, ground, and chewed, it will cause the plant tissue cells to be destroyed. The glucosinolates in it come into contact with endogenous myrosinase and immediately undergo enzymatic hydrolysis to produce isothiocyanates. [5] It is precisely because horseradish, mustard, and wasabi contain a high content of this ingredient and the processing process is delicate that the irritating spicy taste that hits the nasal cavity appears.

In fact, horseradish sauce itself is yellow, and it turns green after adding food coloring.

Piperine, the spicy ingredient of black pepper

Black pepper beef, black pepper chicken rice, and black pepper beef are all delicious dishes, and black pepper is the "magic weapon" for making them. Although black pepper smells very fragrant, if you eat one raw, you will clearly feel its spiciness.

The main pungent compound of black pepper is piperine, which is stored in the outer peel and seed surface of black pepper. Its spiciness is about 1% of capsaicin. [1] Some studies have also mentioned that caryophyllene in black pepper has a strong pungent smell, and 3-carene also has a certain pungent taste. [6] Black pepper is ground into black pepper and black pepper powder, which can fully release the aromatic substances and increase the flavor of the food. However, it must be sealed well, otherwise the aroma will be lost and the spiciness will disappear.

From this we can see that the "spicy" taste of spicy foods is not the same. Chili peppers are spicy because they are rich in capsaicin; scallions, onions, garlic, leeks and other Allium plants are spicy because they are rich in sulfides; ginger is spicy because of gingerol; horseradish, mustard, and wasabi are spicy because of isothiocyanates; black pepper is spicy because of piperine.

What kind of spicy food do you like?

References

[1] Harold Mackey, Food and Cooking: Vegetables, Fruits, Spices, and Grains. Translated by Cai Chengzhi. Beijing Fine Arts Photography Publishing House. August 2013.

[2] Ofori-AsensoR, MohsenpourMA, NouriM, FaghihS, LiewD, MazidiM. Association of SpicyChilliFoodConsumptionWithCardiovascularandAll-CauseMortality: AMeta-AnalysisofProspectiveCohortStudies.Angiology.2021Aug;72(7):625-632.

[3]TammyThornton,DeanMills,andEdwardBliss,Capsaicin:APotentialTreatmenttoImproveCerebrovascularFunctionandCognitioninObesityandAgeing[J].Nutrients,2023,15(6):1537.

[4] Liu Bing, Chang Yuan, Wang Ruifang, et al. Research progress on volatile flavor compounds in Allium plants[J]. Food Science, 2022, 43(03): 249-257.

[5] Zhang Qingfeng. Research on the biologically active components of horseradish - isothiocyanates[D]. Tianjin Commercial University, 2007.

[6] Li Zuguang, Gao Yunfang, Liu Wenhan. Research on flavor components of black pepper[J]. Food Science, 2003(10):128-131.

Author: Xue Qingxin, one of the first nutrition instructors of the National Health Commission, and a registered nutritionist in China

Review | Han Hongwei, Director and Researcher of Risk Communication Department, National Food Safety Risk Assessment Center