Gray?????

Ok so this was my first item making banana purée for my five month old baby girl... I mixed the whole banana along with 2oz formula in a baby blender... I made sure there were no chunks in purée so I blended little bit more... so as soon I opened it the color looked gray...my husband was like oh no throw it away ... not sure if banana purée is suppose to look gray.. usually I watch it on you tube it looks creamy color... so once baby is awake I will try to make apple purée hope it does not turn gray....