Yes, corn starch will react with enzymes in water. Old corn can be soaked in acid for two days. In the process of soaking in water, starch in corn will react with enzymes in water to produce sour taste, which makes corn sour. Under normal circumstances, corn will be sour after soaking in water for about a day. If the soaking time is too long, the sour taste will be stronger.

Clean the old corn before soaking it in water. You can gently brush your skin with a brush or sponge to remove impurities and dirt.