Cornstarch itself does not tenderize meat. However, when used in a velveting marinade with baking soda and oil for dishes like stir-fry, it forms a protective barrier that locks in juices and helps prevent the meat from drying out under high-heat cooking. Cornstarch or any starch such as potato starch, tapioca starch, or arrowroot starch retains the moisture of the meat and gives a little crisp exterior texture to the cooked meat.