What it actually is
Water in a meat, dairy or prepared product is not simply present. Most of it is held inside a structure: immobilised between protein filaments, trapped in a gel network, or bound directly to the protein surface. Only a small fraction is free. Water holding capacity describes how much of that stays where it was put.
Why it matters
It is a yield number and a quality number at the same time. Water that leaves is weight already paid for and no longer sellable, and it is also the first defect a customer sees, because liquid in the bottom of a pack reads as a product that has gone wrong.
What changes it
pH relative to the protein's isoelectric point, salt level, how much protein has been solubilised, the severity of the heat step, and in frozen products how large the ice crystals grow and how many freeze and thaw cycles the product really goes through.
