Eli5: freeze drying. I just can’t wrap my head around how it gives different results even tho both take out water out of say fruit. And also how they evaporate in freezing environment

Question

Eli5: freeze drying. I just can’t wrap my head around how it gives different results even tho both take out water out of say fruit. And also how they evaporate in freezing environment

In: 27

Answer 1

Freezing and boiling temperature of water changes depending on the air pressure. The lower the pressure, the lower the temperature of evaporation.

So at low pressure, water can boil, while still being cold, so it seems weird. At total vaccume pressure the fruit freezes, and then the water just evaporates in place without the fruit changing temperature or really changing its shape.