what causes blood plasma to turn an orange color when you donate when the normal color is sort of green?

Answer 1

It must look sort of green while your donating it. It is always orange-red-blue color. It varies between blue and red according the oxygen saturation. If the container permits oxygen to pass through the barrier it may become a brighter shade of red-orange with exposure.

Answer 2

There are still red blood cells (both whole and broken) in plasma when you donate it... It's not until you put blood into a centrifuge that it separates from these particles.