The only factor that affects the hardness of ice cream is temperature. The required temperature of ice cream is-18℃. If the temperature is higher than-18℃, the structure of ice cream begins to be destroyed, for example, the air inside is released, the ice crystals melt, and the fat particles begin to merge into large fat particles. If the temperature is higher, the ice cream will become liquid.
If other foods in the freezer are frozen and the ice cream is soft, there are two possible situations.
Situation 1: It hasn't been put in for a long time. If it is soft ice cream that has just been made, or hard ice cream that has been in contact with the outside world for a long time, when it is frozen in the refrigerator, because the heat conduction function of ice cream is not as fast as that of steel, the ice cream that has just been put into the freezer of the refrigerator will not become very hard.
Case 2: Specific heat reason. What is specific heat? For example, put iron and water with the same temperature of 10 degrees into a-18 refrigerator. If 20 minutes pass, which temperature will be lower? Steel, of course. Why? This is caused by the molecular structure of the object's ability. The specific heat of water is greater than that of other objects. The greater the specific heat, the more heat will be absorbed or released if 1 degree is increased or decreased. That is to say, because there is more water in the ice cream, it is put into the freezer to release more energy and make it drop to-18 degrees. In addition, the heat released by other foods in the freezer is transferred to the ice cream, and the temperature of the ice cream in the freezer is difficult to drop to-18 degrees, which means that other foods are frozen hard, but the ice cream is still soft.