The mass of a sample may either increase or decrease with temperature or time depending on the specific physicochemical processes occurring. Heating often leads to a reduction in mass because of evaporation of volatile components and various chemical reactions that liberate gasses. On the other hand, the mass of food may increase due to absorption of moisture from the atmosphere. The ability to be able to carefully control the temperature, pressure and composition of the gasses surrounding a sample is extremely valuable for food scientists, because it allows them to model processes such as drying, cooking, and uptake of moisture during storage.