Why do apples turn yellow after cutting them for a long time?

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.

When the apple is peeled, the phenolic substances in the plant cells are oxidized with the air under the action of phenolase, producing a large amount of quinones, causing the apple to turn yellow.

Neoquinones can cause plant cells to turn brown quickly. This change is known as enzymatic browning of food. Therefore, after the apple is peeled, it will change color after leaving it for a while. It's not just apples, pears, and some vegetables (like potatoes, eggplant, etc.). This is also the case.

Browning in this process affects the appearance of the food, lowering the nutrient content of the outer layer, but it is still edible. If the apple is stored 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.

1. The cut apples turn yellow after a long time because of the oxidation reaction, specifically some phenolic substances will react with oxygen under the catalytic action of PPO.

2. After the reaction, quinones will be generated, and with the aggregation of these substances, melanin will be produced, and black pigment is the main reason for the yellowing of apples.

3. Apple is a common fruit in daily life, with high nutritional value, rich in vitamin C, dietary fiber, carbohydrates, a variety of trace elements (potassium, phosphorus, iron, sodium) and a small amount of fat and protein, which is deeply loved by people.

Summary. Dear, I'm honored to have your question The information that the teacher found for you here is: Why do apples turn yellow after cutting, and some are not yellow:

Apples will turn yellow after cutting, and some are not yellowish because when apples are peeled, the phenols in plant cells are oxidized with the air under the action of phenols, producing a large number of quinones. The new quinones can cause plant cells to turn brown quickly, a change called enzymatic browning of food, so apples will change color after peeling and leaving 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 pectic acid and methanol under the action of enzymes.

Why do apples turn yellow after cutting, and some do not turn yellow.

Dear, I'm honored to have your question The information that the teacher found for you here is: why do apples turn yellow after cutting, and some do not turn yellow: apples will turn yellow after cutting, and some do not turn yellow because when apples are peeled, the phenols in plant cells will oxidize with the air under the action of phenols, producing a large number of quinones.

The new quinones can cause plant cells to turn brown quickly, a change called enzymatic browning of food, so apples will change color after peeling and leaving 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 pectic acid and methanol under the action of enzymes.

Recommendations <>

Now that the epidemic is repeated, you must pay attention to safety when you go out, <> go out, wear a mask, wash your hands frequently! Have a great day, <>

The reasons are as follows: 1. Due to the action of tannins in apples, the surface will turn yellow. The tannins react with oxygen in the air and turn brown. Tannins are a phenolic compound with a complex structure of hail, known as tannic acid, and the more tannins there are, the faster the cut fruit changes color.

2. Apples will also turn yellow after they are broken.

Tannins: It is one of the two phenolic compounds contained in wine, especially in red grape wine, which is beneficial to the prevention of cardiovascular diseases. The tannins in wine are usually fermented from maceration of grape seeds, skins and stems, or the tannin in the oak is extracted from the maceration of the macadamia in oak barrels.

The amount of tannins determines the flavor, structure and texture of a wine.