Final answer:
Cryopreservation is the storage of materials at extreme low temperatures, typically for the long-term preservation of biological materials. This technique is critical for maintaining the integrity of samples in fields such as medicine and biology. It differs from refrigeration, which only slows bacterial growth but does not kill bacteria.
Step-by-step explanation:
The storage of materials at extremely low temperatures of between -150°C and -196°C is known as cryopreservation. This process is used in both the industry and biology to preserve biological materials, such as in the long-term storage of food, laboratory cultures, or medical specimens. An example of cryopreservation in practice can be seen in the ultra-low temperatures achieved by storing specimens on dry ice in ultra-low freezers or in special liquid nitrogen tanks (Figure 13.10), which maintain temperatures as low as -196°C. In contrast, the process of lyophilization or freeze-drying involves rapidly freezing the material and then placing it under vacuum so water is removed by sublimation, combining cold exposure and desiccation for long-term storage.
To answer the related question, placing food in a refrigerator does not kill bacteria; it merely slows down their growth. Refrigeration helps in short-term temperature stability but does not sterilize food or biological samples. For sterilization, other methods such as ionizing or nonionizing radiation are required.