What it actually is
As water freezes it leaves the solution, which concentrates everything still dissolved into a shrinking unfrozen phase. Polymer chains are pushed together and reassociate, which is retrogradation driven by freezing rather than by time. Thaw it and the structure has changed; freeze it again and the change goes further.
Why it matters
Specifications are routinely written for one freeze. Real distribution is never one freeze: a product may be frozen at the plant, partly thawed in transfer, refrozen at the depot, and thawed again by the consumer. A formulation tested once and used four times will fail in the field and pass in the laboratory.
What changes it
The starch or hydrocolloid chosen, whether the starch has been stabilised against retrogradation, how fast each freeze happens, and how many cycles there really are. The honest test is the number of cycles the product actually meets, not the number the brief assumed.
