Why aren't apple slices oxidized

After slicing apples, oxidation can be delayed by soaking them in salt water, applying lemon juice, wrapping them with plastic wrap, refrigerating them, or vacuum sealing them. The oxidation of apples is mainly due to the browning of phenolic substances caused by the contact between polyphenol oxidase and oxygen.

1. Soaking in Salt Water

Soak the cut apple slices in light salt water for about 1 minute. Sodium ions in the salt water can inhibit polyphenol oxidase activity and reduce the reaction between phenolic substances and oxygen. This method is easy to operate and does not affect the original flavor of apples, making it suitable for home use. Note that the concentration of salt water should not be too high to avoid apples being too salty.

2. Applying lemon juice

The vitamin C and acidic environment in lemon juice can effectively block oxidative reactions. Apply fresh lemon juice evenly to the cut surface of the apple using a brush, or soak the slices directly in diluted lemon juice. Acidic components can lower the pH value, inactivate polyphenol oxidase, and vitamin C as a reducing agent can delay the browning process.

3. Wrap the apple slices tightly with food grade cling film to isolate air contact. Physical oxygen barrier is the most direct way to prevent oxidation, especially suitable for slices that require short-term preservation. When packaging, it is necessary to ensure that there are no air bubbles left between the cut surface and the cling film, and the recommended storage time is within 2 hours.

4. Cold storage

Low temperature environment can significantly slow down the enzymatic reaction rate. Slice the apple and place it in a sealed container, then refrigerate it at 4 ℃ to extend the shelf life to 4-6 hours. Although low temperature cannot completely prevent oxidation, it can significantly slow down the browning rate while maintaining the crispness of apples, making it suitable for situations that require long-term storage.

5. Vacuum sealing

Use vacuum equipment to remove air from the packaging and seal it, completely eliminating the possibility of oxygen contact. This method can maintain the color and taste of apple slices for more than 12 hours, but requires specialized equipment. It is recommended to refrigerate the slices after vacuum sealing, and consume them as soon as possible after opening.

It is recommended to prioritize lemon juice or salt water treatment when eating sliced apples in daily life, which can maintain nutrition and facilitate operation. If long-term storage is required, a combination of refrigeration and physical isolation methods can be used. Although apple oxidation does not affect food safety, it can reduce vitamin C content. After cutting, it should be consumed as soon as possible to avoid repeated exposure to air. For children or special populations, it is recommended to cut and eat immediately to obtain the best nutritional value, and stored slices should be checked for spoilage before consumption.