What causes the browning of fruits and how can I prevent it in my kitchen?

The browning of fruits is a fascinating topic, and it's great that you're interested in understanding the science behind it. The main culprit behind this browning is an enzyme called polyphenol oxidase (PPO), which reacts with the oxygen in the air to form brown pigments. This reaction is known as enzymatic browning, and it's a common phenomenon in many types of fruits and vegetables.

When you cut or bruise a fruit, the cells are damaged, and the PPO enzyme is released. The enzyme then reacts with the oxygen in the air, turning the fruit's phenolic compounds into brown pigments. This reaction can be slowed down or prevented by reducing the fruit's exposure to oxygen, acidifying the environment, or using inhibitors that block the PPO enzyme.

One way to prevent or slow down the browning of fruits is to use lemon juice or vinegar, as you've already tried. The acidity in these substances helps to denature the PPO enzyme, reducing its activity and slowing down the browning reaction. You can also try using honey or maple syrup, which have antimicrobial properties that can help to prevent the growth of bacteria and other microorganisms that can contribute to browning.

Another way to prevent browning is to use ascorbic acid, also known as vitamin C. Ascorbic acid is a natural antioxidant that can help to neutralize the free radicals that contribute to the browning reaction. You can find ascorbic acid in many fruits and vegetables, or you can buy it in powder form and sprinkle it on your cut fruits.

Some fruits are more prone to browning than others, due to their higher PPO enzyme activity or higher phenolic content. Apples, bananas