Preparation

The food (e.g., cooked Dal Makhani or Paneer Butter Masala) is first prepared exactly as you would eat it at home — fully cooked, seasoned, and portioned.

Freezing (–40°C to –50°C or lower)

The meals are rapidly frozen into a solid block of ice.

Fast freezing creates very small ice crystals, which prevents damage to the food’s cell structure (large crystals would puncture cells and make the rehydrated food mushy).

Primary Drying – Sublimation (under vacuum)

The frozen food is placed inside a vacuum chamber where pressure is drastically lowered (almost vacuum).

Heat is gently applied (usually via shelves or radiant heat).

Because of the low pressure, the ice does *not* melt into liquid water. Instead, it turns directly from solid ice into water vapor — this is called *sublimation*.

Around 90–95 % of the water is removed in this phase, which can take 20–40 hours depending on the product.

Secondary Drying – Desorption

Temperature is gradually raised further while maintaining the vacuum.

This removes the remaining “bound” water molecules that were not frozen (trapped inside the food matrix).

Final moisture content is typically 1–3 %, making microbial growth impossible.

Packaging

The freeze-dried food is immediately sealed in moisture-proof, oxygen-barrier pouches (often with an oxygen absorber) under nitrogen or vacuum to prevent reabsorption of moisture and oxidation.