Here's one of the steps we take when analyzing natural processed coffee samples when they arrive at Sweet Maria's. In this case we are grading a natural that cupped really well but had a good amount of quakers. Natural coffees don't get the same level of machine sorting that washed coffees do and there's usually a mechanical way to remove green, unripe cherries during the washed coffee process that would result in quakers. In the natural coffee process, they must be spotted visually and removed manually. When roasting, it's difficult to tell them apart from light roasted coffee.