When I make sweet potatoes in the microwave they are always paler and slightly bitter. I usually bake 3-4 in the oven, then freeze them indivudually. They are mych sweeter done in the oven. It gives the startches time to turn to sugar and carmelize naturally.
I use green bags which I bought at Giant. I use them for everything! Spinach, lettuce, brocolli, friots...everything lasts longer.
Mel