The diffence in colour will affect heat changes but only from radiant heat ie sun light.
For ambient heat (hot air) the construction material will have a much higher effect. Materials such as aluminium will absorb 3 times as much heat as steel. If you want to keep the air as cool as possible the best product to use is plastic and it has very little heat density.
Another few factors are contact time and surface area. Because the air is only in contact with the metal for a very short time only a tiny bit of the heat will be transfered to the air. Being round, the piping has the lowest surface area to cross-sectional area of any shape.
If you want to keep the air cool then use plastic with heat wrap as plastic doesn't corrode.