פירוש על עבודה זרה 77:12

Hiltit has a sharp taste, and so when it is cut with a knife which has been used to cut nonkosher substances, the taste of the non-kosher substances will go into the hiltit. And although such residue taste is generally considered as “imparting a worsening flavor” and permitted, in this case since the hiltit is sharp the flavor will turn out good. The implications from here are that when one cuts most foods with a non-kosher knife, the food is permitted. But not if the food has a sharp taste.