Why is rapid freezing to temperatures below -40F necessary in lyophilization?

Answer

To ensure the water inside forms small, uniform ice crystals

Rapid freezing at extremely low temperatures prevents the formation of large ice crystals. Large crystals can damage the cellular structure of food, whereas small, uniform crystals help preserve the physical shape, nutritional value, and overall quality of the product throughout the subsequent drying stages.

Why is rapid freezing to temperatures below -40F necessary in lyophilization?
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