Industrial Dehydration Methods for Instant Rice
Hot-Air Drying vs. Freeze-Drying Techniques
Once rice is fully cooked for Instant Rice production, the method used to remove moisture determines the final quality and rehydration speed. Hot-air drying is the most common industrial method, where cooked grains are moved through conveyor belts in a high-temperature environment (typically $70$°C to $90$°C). This process must be precisely controlled to prevent "case hardening," where the exterior dries too quickly and traps moisture inside.\
A more advanced method is freeze-drying (lyophilization). In this process, the cooked rice is frozen, and then placed in a vacuum chamber where the ice crystals sublimate directly into vapor. This leaves behind a highly porous, "sponge-like" internal architecture. While more expensive, freeze-dried instant rice rehydrates much faster and maintains a texture closer to traditionally boiled rice compared to air-dried varieties.