Take drying temperature and time from the material datasheet. Sensitive materials need a desiccant dryer; an ordinary hot-air dryer is not enough.
Dried material picks up moisture again, so size the hopper to your consumption and don't leave material exposed to air for long.
Silver streaks aren't always moisture: excessive temperature and long residence time in the barrel show the same symptom.
This note is general guidance. For exact settings, the material datasheet and the machine maker's instructions are the reference.