What it actually is
Most of it does not happen during frying. While the product is in the oil, steam leaving the surface keeps oil out. The uptake happens during cooling, when the steam stops, pressure inside falls and oil is drawn into the pores that the escaping water opened. The structure left behind decides how much goes in.
Why it matters
It is a direct cost, since oil absorbed is oil bought. It is also a quality defect, because a product that has taken too much oil eats heavy and greasy however crisp it looked leaving the fryer.
What changes it
Coating structure and porosity, the moisture content of the product going in, oil temperature and frying time, and what happens immediately after the fryer. Draining and cooling conditions change the final figure more than most trials allow for.
