Clumping in IQF fruit has two distinct causes with two distinct owners. Dry, loose clumps with no frost inside the liner usually point to insufficient dewatering before the freezing tunnel, which is a processing line issue. Hard clumps with frost or ice sheets inside the liner point to thawing and refreezing in the chain, which is a logistics issue.
Reading the evidence
Open a carton at intake and look before you touch anything. Frost on the inside of the liner means moisture left the fruit and refroze somewhere else, which requires a temperature rise. Clean, dry aggregates with no frost mean free surface water was present when the fruit entered the tunnel and froze the pieces together at the contact points.
Why the distinction is worth learning
It determines who owns the corrective action and who pays. A dewatering problem is fixed at the plant with air knives and screen settings; a temperature problem is fixed with pre-cooling, dock dwell limits and loading discipline. Attributing one to the other guarantees the problem recurs.
Specify it so it can be measured
Put a maximum aggregate size and a maximum clumped percentage into the specification, assessed on the frozen product before any thaw. Without a number, “free flowing” is an opinion. See IQF freezing explained.