Experiments: Mushroom Oil

Version 1: Simple soaking

Ground one oz. porcini mushrooms lightly with mortar & pestle. Heated two cups olive oil pretty hot in microwave. Added mushrooms. Let sit two days.
Result: no significant result. Mushrooms did not appreciably soak into the oil.

Version 2: Grind & boil

Ground one oz. porcini mushrooms to powder with electric coffee grinder. Put in pot with one cup olive oil. Heated to frothing; let simmer about ten minutes. Let cool, bottle. Shake periodically for first two days.
Most mushroom powder has settled, but oil is still cloudy. Bottle has an almost overwhelming aroma of porcini. Decanted oil into separate jar from settled powder. Oil still primarily yellow, not the rich brown of most mushroom oils. Does still smell strong, though.
Flavor came out pretty well -- moderately rich and pretty tasty. Never did get that rich brown color, though.

Version 3: Bake, grind, and mix

Toasted 2/3 oz porcini in toaster oven. Half were actually toasted, the other half baked at 350. Both versions browned very fast. To my surprise, the baked half went faster, apparently because the element was so close. Pulled out before they scorched.
Mixed with 1 cup oil, and left to soak. Did not boil this time. Shake periodically for first two days.
Result:  Strong smell of slightly-burnt mushroom in the oil, but no particular flavor and no dark color.  How do they get that color?