Status of Butter Made from Whey Remnants of Non-Jewish Cheese

Description

The Chasam Sofer rules that if the non-Jewish cheese was made with animal rennet, butter derived from its whey remnants is prohibited because the davar ha-ma'amid permeates the product; if no animal rennet was used, the butter was never included in the rabbinic enactment against gevinas akum and is permitted in communities that follow the lenient custom on non-Jewish butter. Practically, one should not initially encourage purchasing such butter, but after the fact, foods or utensils that came into contact with it need not be forbidden.