freeze dying is based on:
- A- pressure filtration.
- B- sublimation.
- C- polymerization.
- D- pasteurization.
- E- densification.
Out of the options you provided, freeze drying is based on: B. Sublimation.
Here's why:
- Freeze drying:
This process involves removing water from a material by turning it directly from a solid (ice) to a vapor (sublimation) under a vacuum. This eliminates the liquid phase, preventing damage to delicate structures and preserving the original characteristics of the material.
- Sublimation:
This is the phase change where a solid directly transforms into a vapor without going through a liquid phase. This principle is crucial for freeze drying as it allows water to be removed gently without affecting the structure of the material.
- Pressure filtration:
This technique uses pressure to force a liquid through a filter, separating solids from liquids. While potentially used in some pre-processing steps before freeze drying, it's not the core principle of the freeze-drying process itself.
- Polymerization:
This is the process of linking individual molecules together to form larger chains, which doesn't relate to removing water from a material.
- Pasteurization:
This involves heating a liquid to a specific temperature to kill harmful bacteria. It's not relevant to freeze drying, which focuses on water removal.
- Densification:
This refers to increasing the density of a material, opposite to the desired outcome of freeze drying, which is to create a lightweight, porous product.
Therefore, sublimation is the essential principle behind the freeze-drying process.
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