Is this a “special process” under the Food Code? Yes. A PHF (TCS) food is being freeze dried to be non-PHF (non-TCS).
The technology and equipment for freeze drying has improved to the point that small operators and even some home preservers can join in. Pictured is a line of freeze dryers from Harvest-Right (look them up on your own). From a food safety standpoint, this “special process” is low risk. Foods MUST be frozen first. Then the water is removed by sublimation (solid direct to a gas) inside the machine. The machine also maintains the freezing temperature, so time to dry is not important. The loss of flexibility or pliability indicates food dryness. A dry, crunchy, food item is likely to have a water activity close to 0.3, well below the 0.85 pathogen cut off level.
Molecular gastronomy combines artistic culinary experiences and passion with the scientific and technical foundations of food science. Freeze-drying various foods is one of the methods currently being explored by these cutting edge chefs.