If done well, deep-frying does not make food too greasy, because the moisture in the food repels the oil. The hot oil heats the water in the food, steaming it from the inside out. The water vapor pushes the bubbles toward the surface of the oil. As long as the oil is hot enough and the food is not in the oil for too long, oil will only enter the surface of the food. However, if the food is cooked in the oil for too long, much of the water will be lost and the oil will begin to penetrate the food. The correct frying temperature depends on the thickness and type of food, but is usually between 175 and 190 °C (345–375 °F). 