Why do cut apples change color, and why do cut apples change color

Apples contain iron, and when exposed to air, the iron oxidizes and rusts.

After the apple is plucked from the tree, it has been separated from its mother, but its breathing activity is still active. This is due to the presence of phenolic substances in apples, which maintain their respiration. When apples are peeled, the phenols in plant cells are oxidized with the air under the action of phenols, producing a large amount of quinones.

The new quinones can cause plant cells to turn brown rapidly, a change called enzymatic browning of food. So apples will change color after peeling and leaving them for a while. This is also the case for apples and pears, as well as some vegetables (such as potatoes and eggplants).

This browning affects the appearance of the food, reducing the nutrient content of the outer layer, but it is still edible. If the apple is left for a long time after peeling, the oxidative decomposition of plant cells in the air is intensified, the nutrients in the outer layer of the apple are decomposed more, and the pectin substances are further decomposed into pectin acid and methanol under the action of enzymes, making the flesh loose, moist, discolored, tasteless, and even rotten and deteriorated.

So, it is best to eat the fruit immediately after peeling. An easy way to control the discoloration of apples when giving apples to babies is to immediately soak the peeled apples in cold boiled water, sugar water, or light salt water to isolate them from the air to prevent the oxidation of phenols in plant cells. However, from the point of view of preserving the nutrients in apples, peeled apples should not be soaked for too long.

The apple is cut and placed in the air, and it doesn't take long for the cut surface of the apple to turn dark brown. This is mainly due to phenolic oxides produced by the oxidation of phenolic chemicals in apples by oxygen in the air.

Because apples contain iron, they are oxidized to iron oxide with air and are red.

Apples contain an oxidase, when the skin of the apple is peeled, the air meets the pulp, and the organic matter in the pulp is oxidized and discolored under the catalysis of oxygen enzymes, and the apple becomes an unsightly black-brown color.

Because apples contain vitamin C that is easily exposed to air, it is oxidized by oxygen after being cut and exposed to air.

Many vegetables and fruits automatically change color: peeled apples and pears, sliced potatoes, lotus roots.

Wait. Cause of discoloration: Although fruits and vegetables are picked, their internal metabolic activities have not stopped, various enzymes are still "working", when they are peeled or peeled, a polyphenolic chemical contained in their bodies——— tannins, will be under the action of enzymes, and oxygen in the air will have a chemical reaction to produce quinone compounds, and the color of food will also turn brown.

Loss: First of all, the sensory influence, the color and taste of the food are not as good as before the discoloration, which affects the desire to eat; The second is that the nutritional value is affected, and it is conceivable that when the "discoloration" reaction is underway, some other nutrients will also be oxidized, with vitamin C being the most severely lost.

Prevention: Apples are easy to change color after cutting or peeling, if you soak them in lemonade? It won't change color.

Be careful that the lemonade should not be very strong. It is also fine to soak in salt water, but the apples will be a little soft after soaking, so it is best to soak them in lemonade.

The discoloration of the cut apple is due to the oxidation of the cut apple when it is oxidized by air.

Oxidation, in a narrow sense, refers to the chemical reaction of oxygen with other material elements, and is also an important chemical unit process. Oxidation, in a broad sense, refers to the process by which a substance loses electrons (oxidation number increases).

Oxidation is a process that breaks down matter and releases energy. It is the process by which the atoms of the oxidized substance lose electrons and the oxidizing agent gains electrons.

There are many examples of electrons seized by oxygen radicals that are common around us, such as: rusting nails, turning brown apples, fading blue jeans, etc.

Expand your knowledge: Ways to prevent oxidation in apples:

Use lemon juice. Lemons contain citric acid, which is antioxidant.

Sprinkle the lemon juice directly over the apple slices in a bowl and stir to coat well. You can also use a pastry brush to spread lemon juice on the flesh of the fruit that has been exposed to air.

You can also mix cold water and lemon juice in a bowl and soak apple slices to prevent oxidation. Ratio of one tablespoon of lemon juice to a glass of water. Just soak the apples for 3 to 5 minutes before discarding the water and rinsing the apples.

2.Use salt. Salt is a natural preservative that effectively stops apples from oxidizing.

Dissolve half a teaspoon of salt in about 946ml of cold water. Place the sliced apples in salted water and immerse for 3 to 5 minutes.

3.Blanch the apples in boiling water. Boiling water basically renders the enzymes in apples useless, preventing them from chemically reacting with oxygen in the air.

Just put the apples in a pot of boiling water for about 5 minutes, remove the apples, and wash them in cold water.

The reason why apples change color after cutting is because the phenolic compounds in the pulp react with the air, and the flesh changes color after oxidation, and the longer the flesh is oxidized, the darker its color will be. To avoid discoloration after the apple is cut, you can soak it in water after cutting it or put a few drops of lemonade on the cut side.

The reason why apples change color when cut

nbsp;The reason why apples change color after cutting is because the phenolic compounds in them are in contact with the air to produce an oxidation reaction, and the flesh of the apple will change color due to oxidation, and the longer the apple is cut, the darker the color will become.

Ways to avoid discoloration after cutting apples

1. If you want to avoid the phenomenon of discoloration after the apple is cut, you can soak the apple in water immediately after cutting, so as to avoid the rapid oxidation reaction between the apple pulp and the air.

2. In addition, you can also drop a few drops of lemonade on the cut surface after the apple is cut, which can not only avoid the phenomenon of discoloration of the apple, but also maintain the original flavor of the apple.

There are these reasons why apples change color after they are cut:

1. The discoloration of apples after cutting is caused by oxidation reactions.

2. After cutting the apple, the inside of the pulp is exposed to air and comes into contact with oxygen, causing the enzymes in the pulp to react with oxygen and produce oxidized substances.

3. In the oxidation reaction, the phenolic substances in apples are oxidized to phenol under the catalysis of enzymes, and reddish-brown or dark brown spots appear.

4. In addition, after cutting the apple, the surface of the pulp is also susceptible to bacterial and microbial infection, which accelerates the oxidation reaction and causes the pulp to change color faster.

5. Therefore, apples should be eaten as soon as possible after being cut, or put them in a sealed bag and refrigerated as soon as possible to slow down the oxidation reaction and maintain the freshness and nutritional value of apples.

Apple's benefits are as follows:

1. Lower cholesterol: Keep blood sugar stable, and effectively lower cholesterol.

2. Anti-cancer and anti-cancer: reduce the risk of lung cancer, prevent lead poisoning, and proanthocyanidins can prevent colon cancer.

3. Vascular cleaners improve respiratory system and lung function, and protect the lungs from pollution and soot.

4. Promote gastrointestinal peristalsis: assist the human body to discharge waste smoothly and reduce the harm of harmful substances to the world.

5. Maintain acid-base balance: apples are alkaline foods, and eating lead apples can quickly neutralize excessive acidic substances in the body (including acids produced by sports (sports food) and acidic metabolites produced by acidic foods such as fish, meat, and eggs), and enhance physical strength and disease resistance. <>