Whether you're nine, 19, or 99, it's hard to resist ice cream. When served fresh, it’s all you could ever dream of, but allow it to soften and refreeze, and the resulting product seems to change character completely.

To make ice cream, you must mix milk, cream, sweetener, and sometimes eggs; then heat the mixture for safety, and add it to a machine to be cooled and filled with air, which increases the volume. Microscopic air bubbles and ice crystals develop during the freezing process to give ice cream a velvety texture.

When ice cream freezes, ice crystals form to trap sugar and carbs, and air bubbles get coated with fats which attract proteins. When ice cream melts, the sugars are released from the crystals and the air bubbles escape, which makes the fats and proteins thinner, meaning you can never regain the old texture upon refreezing.