QUESTION: Why is there a need for two Rabbinic prohibitions: chalav akum (unsupervised milk) and gevinas akum (unsupervised cheese)? Shouldn’t gevinas Akum anyways be forbidden, since presumably the cheese was made using unsupervised milk?
ANSWER: The Chasam Sofer (YD 107) writes, based on the explanation of the Kesef Mishneh (Rav Yosef Karo), that the prohibition of chalav akum applies only to milk in its original state. However, if milk was changed by a non-Jew into another form before it was sold to a Jew—for example, if milk is changed into cheese or butter—the prohibition of chalav akum no longer applies. The Shach (115:27) as well explains that butter may be purchased from a non-Jew, since butter was not included in the gezeira of Chazal and there is no concern of it containing milk from a non-kosher animal, since non-kosher milk does not congeal into butter.
According to Chasam Sofer, the same logic originally applied to cheese. Before Chazal forbade gevinas akum, it was permitted to buy cheese from a nochri, although it was forbidden to buy unsupervised milk. It was only later that Chazal forbade cheese, due to the concern that it might have been coagulated using non-kosher animal rennet. Because of this, the prohibition of chalav akum does not apply to butter, provided that it is dry and does not contain any milk droplets, though some communities have a custom not to use this.
