Why do apples change color after peeling and not eating for a while?

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.

The best way to do this is to rub the skin with salt before peeling, then wash it off, and then peel the apples, so that the apples will not oxidize, and they will last longer than soaking them in salt water after peeling, and they will not have a salty taste.

When the apple is peeled or cut and left for a while, the color of the cut surface will change from light to dark and finally dark brown. The discoloration reaction occurs mainly due to the presence of phenolic compounds in these plants. For example:

Polyphenols, catechols, etc. Phenolic compounds are easily oxidized to quinones, that is, they change color and turn yellow, and the color gradually deepens with the increase of the amount of reaction, and finally turns dark brown. The oxidation reaction occurs due to the contact with oxygen in the air and the release of phenol oxidase in the cell.

Phenolic oxidase exists in organelles and cannot come into contact with phenolic compounds until the tissue is damaged, and oxygen in the air cannot enter, so no oxidative discoloration reaction occurs. When the cell tissue is damaged, phenol oxidase is released to contact with phenolic compounds, catalyzing the oxidation of phenolic compounds, coupled with the action of oxygen in the air, a discoloration reaction will occur. Among them, polyphenols can be directly oxidized to quinones and change color.

Catechol molecules, on the other hand, polymerize under the action of phenol oxidase. Two catechol molecules are linked together to form catechol dimers, which in turn can be joined in pairs to form tetramers. The individual catechol molecules and their dimers and tetramers are all colorless, but catechol tetramers can form multimers, which are purple.

So the more polymers are formed, the darker the color of the incision surface will be. When apples change color, the amount of vitamin C will decrease, affecting the nutritional value. To prevent the apple from changing color after cutting, the best way to keep it out of contact with the air is to soak the apple in salt water.

Let the cut apple not change color The color of the cut apple will quickly dull and affect the appearance, is there any trick to change it? It's as simple as dripping lemon juice on the cut side of the apple, which not only does not change color, but also retains the original flavor. In addition, some fruits that are easy to change color can also be treated in this way, and the effect is excellent!

The above is from knowing.

After peeling the apple, it can be eaten with discoloration, there are phenolic compounds in the apple, which are easy to be oxidized into quinones, that is, the discoloration reaction becomes yellow, but the flesh is not corroded and infected, you can clean it and continue to eat it, or you can cut off the yellow side and eat it again, which will not affect the human body. If it is stored for a long time, more than 1 day, it can no longer be consumed.

Apple is a plant of the genus Apple in the subfamily Apple of the Rosaceae family, and its tree is a deciduous tree. Apples are highly nutritious, rich in minerals and vitamins, rich in calcium, which helps to metabolize excess salt in the body, and malic acid can metabolize calories and prevent obesity in the lower half of the body. Apples are a low-calorie food, producing about 60 kilocalories per 100 grams.

The nutrients in apples can be soluble and easily absorbed by the human body, so they are known as living water. It is conducive to dissolving sulfur elements, making ** lubricating and soft.

I can eat it. There are phenolic compounds in apples, which are easy to be oxidized into quinones, that is, the discoloration reaction turns yellow, but the flesh is not corroded and infected, you can wash it and continue to eat, or you can cut off the yellowed side and eat it, which will not affect the human body. If it is stored for a long time, more than 1 day, it can no longer be consumed.

The apple can be eaten after peeling and changing color, there are phenolic compounds in the apple, and the posture is easy to be oxidized into quinone compounds, that is, the discoloration reaction becomes yellow, but the flesh is not corroded and infected, you can wash it and continue to eat, you can also cut off the yellowed side and eat it again, which will not affect the human body and extinction. If it is stored for a long time, more than 1 day, it can no longer be consumed.