Yes, you can store onion juice. It's best to use it fresh, but you can preserve it for up to a week by storing it in an airtight container in the refrigerator. However, keep in mind that the potency of onion juice gradually diminishes over time, so it's always best to use it as soon as possible for optimal results.
You can also extend the storage time of onion juice by adding small quantities of common table salt, cooking oil, or a few drops of lemon juice. These additives help to preserve the juice's freshness and prevent spoilage.
While it is possible to freeze onion juice, it can cause the juice to become watery and less effective. If you choose to freeze it, make sure to thaw it completely before using it.
Note: Restaurants commonly store cut onions in the refrigerator for extended periods. However, this is usually done for culinary purposes and not for hair treatments.
