Why do fried onions turn green slowly?

The reasons why the fried onions slowly turn green are as follows:

Onions contain a lot of flavonoids, which meet metals such as iron, aluminum, and lead, producing complexes of different colors such as blue, blue-black, and brown. Therefore, when cutting vegetables with an iron knife, or frying onions in an iron or aluminum pot, the color of the finished dish is dark and not bright.

Dip some dry flour and mix well before stir-frying, which can prevent flavonoids from discoloring in direct contact with metals such as iron and aluminum.

Chemical reasons: It will be oxidized after high temperatures, and the green color after oxidation is not beneficial to the body, try not to eat it.

So it is advisable not to eat it.

Onions contain a lot of flavonoids, which react with metals and turn into green, blue, blue-black, ......

When the onion is cooked, it will slowly change to other colors, which is a normal reaction.

1.Step Category: Overall Introduction Required Tools Raw Materials Methods Steps Precautions.

2.General Knowledge: Direct questions give specific reasons in detail Reason introduction.

I'm from the onion-rich region of southern Fujian, and we've never copied onions like yours! It's amazing. Don't eat it!

It shouldn't be toxic! Maybe you fried it too well, or maybe there was another operational mistake, and it became like that! Cook it again and see.

That onion scrambled egg is delicious, huh!

Onions contain a lot of flavonoids, and flavonoids will change color when they encounter metals such as iron, aluminum, and lead.

It's been in contact with the air for a long time and oxidizes off!

Summary. Hello dear, how to fry onions without blackening The method is as follows:1

The onion is stirred with dry flour after it is cut, and then it will not turn black when stir-frying, and it is best to fry the onion over high heat, and put salt and cornstarch when it comes out of the pot, so that the onion will be more tender, and sprinkle a little green onion after serving, and the effect will be better. 2.After the onion is cut, if it is not immediately oiled, then put it in clean water to prevent oxidation, which can effectively prevent the onion from turning black.

How to fry onions without blackening.

Hello dear, how to fry onions without blackening The method is as follows:1The onion is stirred with dry flour after it is cut, and then it will not turn black when stir-frying, and it is best to fry the onion over high heat, and put salt and cornstarch when it comes out of the pot, so that the onion will be more tender, and sprinkle a little green onion after serving, and the effect will be better.

2.After the onion is cut, if it is not immediately oiled, then put it in clean water to prevent oxidation, which can effectively prevent the onion from turning black.

Here's how to make it:1Peel the onion, soak it in cold water for a while, then cut it into small pieces.

2. Wash the tenderloin, cut it into thin slices, and marinate it with chopped chili, light soy sauce, starch and cooking wine for about 10 minutes. 3. Sit in a pot to heat the oil, wait for the oil temperature to be 8 hot, slide into the shredded meat, quickly disperse, and fry until the meat slices change color and break off. 4. Add the onion and stir-fry for a while until the onion is fragrant, add a little salt and then start the pot.

Onions are a vegetable, but they contain a certain spicy flavor that can enhance the body's ability to fight viruses. There are many ways to eat onions, you can eat them directly, you can soak them in vinegar, and you can also fry them. Some people like to eat onions very much, but it should be noted that because onions have a spicy taste, they may harm eye health and damage health when cutting onions.

In addition, eating onions every day may also damage the gastrointestinal mucosa, resulting in impaired gastrointestinal function and causing certain harm to intestinal health. Therefore, people with gastritis or stomach ulcers should not eat onions to avoid aggravation of the condition.

The above information is ** on the food network.

Onions are an ingredient that contains a lot of natural sugars, and a series of chemical reactions occur during cooking, including the Maillard reaction. This reaction causes the color of the food to darken, which turns the onion black.

Specifically, when an onion is heated, the natural sugars in it are broken down into sugars and amino acids. These sugars and amino acids combine at high temperatures and form a brown compound called a Maillard reaction product. This compound darkens the color of the food, which turns the onion black.

In addition, the sulfur compounds contained in onions may also react with heat to produce discoloration. When the onion is heated, the sulfur compounds break down into ammonia and hydrogen sulfide. Hydrogen sulfide combines with iron ions to form black iron sulfide.

In conclusion, onions undergo several chemical reactions during cooking, causing them to darken in color and thus turn black. While this discoloration may affect the appearance of the food, it does not affect its taste and nutritional value.

The main reasons why onions turn black when they are fried and put are as follows:

1. The hot temperature is too high: The sugar content in the onion is very high, and the hot temperature is too high, which will cause the sugar cubes on the surface of the onion to burn and turn black.

2. The temperature of the hot oil is too high: there is a lot of starch in the onion, if the oil temperature is too high, the surface of the onion will precipitate the starch and turn black.

3. Put the onion for too long: If you put the onion for too long, the active substances on the surface of the onion will be oxidized and turn black.

4. Cooking time is too long: Cooking time too long will also cause the active substances on the surface of the onion to be oxidized and turn black.

5. Acidic conditions: If the ingredients put in during the cooking process have a certain acidity, then the onion will turn black after the reaction.

6. Excessive salt: If too much salt is added, the active substances on the surface of the onion will react and turn black.

The above points are the reasons why onions turn black when they are fried. During the cooking process, you can take the methods of putting less salt and cooking on low heat to protect the onions more carefully so that they do not turn black. When cooking onions, you can choose to put a pinch of spare sugar in the pan to enhance the crunchy texture of the onions, and also prevent the onions from crystallizing and turning black when they are cooked.

The iron pan reacts with the onion, causing the onion to turn black.

This is a normal oxidation phenomenon, and a closer look reveals that the color of the onion is closer to a mixture of dark green and dark blue. When frying onions, add more oil and increase the speed of stir-frying can alleviate oxidation. After using the iron pot for a period of time, a thin film will form between the metal and the air to prevent oxidation, and it is not easy to change color when stir-frying onions and lotus root slices.

Onions contain calcium, phosphorus, iron, vitamin B1 and other trace elements, which contains propylene sulfide, which can improve the absorption rate of vitamin B1 in the gastrointestinal tract, and lean meat is also rich in vitamin B1, so fried meat on onions can ensure that the body can better absorb vitamin B1; Vitamin B1 is a coenzyme necessary for carbohydrate metabolism and can enhance carbohydrates.

Onions contain an enzyme called polyphenol oxidase, which is released when an onion is cut or cooked. Polyphenol oxidase can catalyze the oxidation of phenolic compounds in onions to quinoline compounds, so that the color of onions changes from white to brownish-black.

In addition, when the onion is cut or cooked, the sulfur compounds in it are also released. These sulfur compounds can react with ammonia to form hydrogen sulfide, which gives onions a pungent smell. When the onion is cooked or left out for a while, the hydrogen sulfide further breaks down into sulfate and water, which can also cause the onion to turn black.

Therefore, the fact that onions turn black after being fried for a while is due to the action of polyphenol oxidase to catalyze the oxidation of phenolic compounds and the decomposition of hydrogen sulfide.

The reason why the onion turns black after being fried for a while is because the onion contains an ingredient called citric acid, and when the onion is cooked, the citric acid reacts with iron ions (Fe2+) to form a black ferrite citrate, which turns the onion black.

If it turns black during stir-frying, it is likely to be due to some chemical reaction, and it is edible.

Onion cells contain more sulfur-containing bioactive substances, and these sulfide-containing substances can be generated under the action of allicinase contained in onions, such as thiosulfinate, propylthiosulfinate, and allyl thiosulfinate. These substances undergo a series of reactions to form pigments. Usually the blue pigment is initially formed, and the blue pigment is unstable and gradually converts into yellow pigment, and the coexistence of the two becomes green.

Onions usually appear as a side dish, but they have a high nutritional value. Onions contain proteins, carbohydrates.

Volatile oils, malic acid, calcium, phosphorus, iron, vitamin A, vitamin B1, vitamin B2

Niacin, vitamin C and 18 amino acids.

and other nutrients, it is a rare health food.

The iron pot reacts with the onion, so it causes the onion to turn black, which does not affect the consumption.

1. Onions are rich in calcium, phosphorus, iron, vitamin B1 and other trace elements, including propylene sulfide, which can improve the absorption rate of vitamin B1 in the gastrointestinal tract, and lean meat is also rich in vitamin B1. Stir-fried meat with onions ensures better absorption of vitamin B1 by the body.

2. Vitamin B1 is a necessary coenzyme for carbohydrate metabolism, which can enhance the oxidation function of carbohydrates, inject energy into the tired mind and body, maintain the normal activities of nervous tissue, muscles and heart, and thus improve mental condition. Therefore, often eat some onion fried meat, which can have the effect of refreshing and eliminating fatigue. It is especially suitable for people with cardiovascular and cerebrovascular diseases to accompany daily meals.

Stir-fry onions, remember, be sure to cook at high temperatures, so that the fried dishes are delicious, if the water is not delicious at low temperatures, the onions will gradually turn yellow when fried at high temperatures, and you can also fry onions with eggs. You can give it a try!