What it actually is
When the product goes into boiling water, anything not locked into a structure is free to leave. In a starch noodle that is mostly amylose that never reassociated. In pasta it is starch not contained by the gluten network. The water turns cloudy because the product is dissolving into it.
Why it matters
It is yield, and it is also the reason the product is sticky and the water has to be changed. A consumer reads cloudy water and a gluey surface as poor quality long before anyone measures anything.
What changes it
Amylose content of the starch, how completely it retrograded during ageing and drying, drying conditions, and cooking time. Fixing it at the cooking step is treating a symptom at the point of least leverage.
