In certain conditions, fungi may grow on Orchiata. If the product is left in warm moist conditions, it can encourage fungi growth.
Often you will see a fine whitish grey layer of fungi on Orchiata when you open the bag. These are most likely Penicillium or Paecilomyces. These are not detrimental to your plants; they are often beneficial as they help to prevent the colonisation of pathogenic fungi. In most cases, when the material is moved or shifted around the fungi is disturbed and will disappear.
Washing Orchiata to remove fungi is unnecessary and, as a micro-organism, the fungi will likely still be present after washing.