It is never permissible to eat any non kosher food. However when a non kosher food is blended and/or mixed into a mixture with kosher foods and has certain required conditions met it is nullified by the majority of kosher food and is therefore permissible. For the purpose of our question at hand, one of these conditions is that it not be intentionally nullified. For this reason if a certain vegetable type that requires checking (because it has been found to contain insects in the past) is blended, as called for in the recipe, and that is the normal way to prepare the food it is not considered to be an intentional nullification, as there is only a fear that it MAY have insects. But if heaven forbid insects are seen on the food, it would be assur to nevertheless chuck that food in the blender and intentionally nullify the insects.