remove enzymes and oxygen, and seal it to isolate oxygen.

one is to remove enzymes, and the other is to remove oxygen. Before eating, soak the cut apples in a container filled with water, so as to avoid the long-term exposure of the sliced apples to oxygen. The same effect can be achieved by coating the sliced apple with syrup and honey and covering the surface of the sliced apple with sugar.

All these have created an isolation membrane that isolates apple tissues from the air, and more importantly, inhibited the diffusion of oxygen in apple cells. Oxygen is prevented from contacting with PPO and iron contained in plant cells.

Extended information

Certain fruits and vegetables have their own "switch" to destroy themselves. At the moment of cutting with a knife, the self-destruction of fruits and vegetables began. Its touch and color began to change, and it became no longer crisp and neat, and its surface also changed to brown. This is actually the most basic phenomenon called oxidation. If you try to interpret the nutrients of these plants, you will find that they all contain iron.

if it's just iron, it won't react. Although most foods contain iron, it doesn't mean that they will "rust" immediately. In fact, a trace enzyme called polyphenol oxidase is promoting this process. Polyphenol oxidase, also known as PPO, can be found in chloroplasts of plant tissues.

Through the injured food tissue, the enzyme comes into contact with the oxygen in the atmosphere and clings to the surrounding compounds. Oxygen, a famous loner in the chemical field, is very easy to react with other atoms and chemicals. When the compounds contained in apples acquire oxygen atoms, they are more likely to react with other substances around them. These reactions produce melanin, which has a brown color-changing effect.

People's Daily Online-Revealing a few tips for cutting apples without changing color: coating honey to block oxygen.