Eat Right Practice Exam

Which quick-freezing process incorporates very low temperatures with liquid nitrogen or carbon dioxide?

1. Air blast freezing

2. Cryogenic freezing

3. Plate or contact freezing

4. Immersion freezing

The correct answer is: Cryogenic freezing

The quick-freezing process that incorporates very low temperatures achieved through the use of liquid nitrogen or carbon dioxide is known as cryogenic freezing. This method utilizes the extremely low temperatures of these substances to rapidly freeze food items, which helps in preserving the texture, flavor, and nutritional value of the food by minimizing the formation of ice crystals. With cryogenic freezing, the temperatures can drop to around -196°C (for liquid nitrogen) or -78.5°C (for solid carbon dioxide), allowing for a very quick transition from a liquid to a frozen state. This speed of freezing is crucial because it reduces the size of ice crystals that form within the food, leading to a smoother texture and less damage to the cellular structure. In contrast, air blast freezing uses cold air circulated around the food, which can take longer, potentially leading to larger ice crystal formation. Plate or contact freezing involves direct contact with cooled surfaces, and immersion freezing entails submerging food in a cryogenic liquid, but the term “cryogenic freezing” specifically relates to using liquid nitrogen or carbon dioxide as the cooling agent.