Do you need to rinse quinoa or not? Conventional wisdom has it that you need to rinse quinoa before cooking. Why? Quinoa seeds are coated with saponin, a bitter substance that protects the seeds from predators. However, most quinoa sold in the U.S. is pre-rinsed so there’s no need to do this. If you want to be cautious, go ahead and give it a rinse: put the quinoa in a bowl, cover it with water, swish it around and then drain it in a fine-mesh sieve.