Final answer:
Freezing food stops microbial growth and can kill certain microbes. Freeze drying works by reducing atmospheric pressure and enhancing evaporation, resulting in dried food. Freezer burn, which does not mean food is spoiled, can be minimized with proper storage.
Step-by-step explanation:
Freezing food below -2 °C is effective in halting microbial growth and in some cases killing susceptible organisms. This process can preserve food quality and safety, as it prevents bacteria from reproducing, which is why frozen foods need to be thawed carefully following USDA guidelines. Using methods such as thawing in the refrigerator or using a microwave helps maintain safe temperatures that do not promote bacterial growth. However, once thawed, food should be treated as perishable since microbial activity can resume.
The process known as freeze drying works on the principle of reducing atmospheric pressure around the food, thereby reducing the partial pressure of water and enhancing the evaporation of water from the food. This accelerated evaporation and sublimation lead to a decrease in food temperature and remove moistness, resulting in dried food. This technique is great for preserving food while maintaining its nutrition and flavor qualities.
When it comes to sublimation in freezer conditions, this phenomenon can lead to freezer burn, which occurs when water vapor sublimes from the food's surface, leaving behind a dry and mottled appearance. Although freezer burn does not mean the food is spoiled, it can affect its texture and flavor. Proper packaging and temperature control can minimize this effect. In the realm of microorganism life, low temperatures present in refrigeration and freezing can inhibit cellular functions, such as enzyme activity, and cause damage to cells due to ice crystal formation.