Chalav Yisrael and Powdered Milk
According to the midrash quoted by Rashi, the baby Moshe refused to nurse from non-Jewish women, although this is not the way we use the term Chalav Yisrael in this article.

Question:
Dr. Levy asks me the following: “Friends of ours keep chalav Yisrael, but they will use foods made with non-chalav-Yisrael powdered milk. But I know from my professional work that one can purchase powdered mare’s (female horses) and camel’s milk – they are considered specialty items. So, why is there any difference between using non-chalav- Yisrael powdered milk and non-chalav Yisrael fluid milk?”
The Mishnah (Avodah Zarah 35b, 39b) proscribes consuming milk that a gentile milked unless a Jew supervised the milking, a prohibition called chalav akum, out of concern that the milk may have been adulterated with milk of a non-kosher species. In a different article (The Milky Whey), I noted that there are several opinions as to how to define the prohibition. The most lenient approach is that of the Pri Chodosh (Yoreh Deah 115:15), who understands that one needs to be concerned about chalav akum only when the non-kosher milk is less expensive than the kosher variety, or it is difficult to sell. However, when kosher milk is less expensive, the Pri Chodosh contends that one does not need to be concerned that the gentile would add more expensive specialty non-kosher milk into regular, kosher milk.
On the other side of the spectrum, the Chasam Sofer maintains that the prohibition has a halachic status of davar shebeminyan, a rabbinic injunction that remains binding, until a larger and more authoritative body declares the original sanction invalid, even when the reason the takanah was introduced no longer applies (see Beitzah 5a). Since a more authoritative beis din never rescinded the prohibition on unsupervised gentile milk, consuming this milk involves a serious violation. The Chasam Sofer requires that a Jew must be able to observe the milking, and if not, the produced milk is completely non-kosher because of the rabbinic injunction, even when the non-Jew has no incentive to adulterate the product.
In between these two positions, there is the opinion of Rav Moshe Feinstein and the Chazon Ish (Yoreh Deah 41:4) that in a place where non-kosher milk commands a higher price than kosher milk, it is still prohibited to use non-supervised milk. However, Rav Moshe understands that the takanah did not specifically require that a Jew attend the milking, but that one is convinced that the milk has no admixture of non-kosher. However, whenever it is certain that the kosher milk is unadulterated, halacha considers the milk “supervised” (Igros Moshe, Yoreh Deah 1:47).
How can one be certain? The Mishnah recommended an obvious way: have a Jew nearby who may check at any moment. Of course, this method is not foolproof, but halacha did not require more.
Is there another way that one can be certain? Allow me to use my own example to explain Rav Moshe’s approach. Dr. Levy, our questioner, runs laboratory tests on a sample of unsupervised milk and concludes, with absolute certainty, that it is 100% sheep’s milk. However, no Jew supervised the milking. Is the milk kosher?
According to Rav Moshe’s analysis, this milk is certainly kosher, since we can ascertain its source.
In his earliest published teshuvah on the subject, Rav Moshe explained that when the government levies fines for adulteration of cow’s milk, the fear of this fine is sufficient proof that the milk is kosher. In later teshuvos, he is very clear that other reasons why we can assume that the milk is kosher are sufficient proof, including that normal commercial enterprises assume that standard milk is bovine milk (Igros Moshe, Yoreh Deah 1:48, 49).
Being stringent
Although Rav Moshe concludes that where one can rely that the standardly available milk is kosher there is no prohibition of chalav akum, he still rules in a different teshuvah that a chinuch institution should use only chalav Yisrael products, even if all the children come from homes that do not use chalav Yisrael exclusively. He contends that part of chinuch is to show children that one follows a stricter standard, even when halacha does not necessarily require one.
Powdered milk
We can now address the question mentioned above: “Friends of ours keep chalav Yisrael, but they will use foods made from non-chalav-Yisrael powdered milk. But I know from my professional work that one can purchase powdered mare’s and camel’s milk – they are considered specialty items. So, why is there any difference between using non-chalav- Yisrael powdered milk and non-chalav-Yisrael fluid milk?”
Those who allow use of non-chalav-Yisrael milk powder follow the opinion presented by Rav Tzvi Pesach Frank, Rav of Yerushalayim until his passing a little over sixty years ago and one of the greatest poskim of his era. Rav Frank assumed that the halacha follows the Chasam Sofer, who requires Jewish supervision to permit the non-Jewish milk, and did not accept the heterim of the Pri Chodosh, nor that of the Igros Moshe and the Chazon Ish. Nevertheless, Rav Frank permitted powdered milk from an unsupervised gentile source, for a very interesting reason.
The poskim permit using cheese that is gevinas Yisrael and butter, even when these products are made from unsupervised milk. (I discussed both of these topics in other articles — How Do We Make Kosher Cheese?, and The Great Cottage Cheese Controversy). Why did they permit this? Because non-kosher milk is low in casein, and, therefore, it does not curd, which is the first step in producing cheese. It is also low in milkfat (also called butterfat or cream), which makes it nonprofitable to make butter from non-kosher milk. (Those curious are invited to read the highly entertaining responsum of the Melamed LeHo’il, 2:36:2, on this topic.) For these reasons, even in the days of Chazal, one could assume that a gentile would not add non-kosher milk when he intends to produce either cheese or butter, and therefore, these items were excluded from the prohibition of chalav akum.
May powdered milk be treated like cheese and butter?
Rav Frank notes that there is a qualitative difference between cheese and butter, on the one hand, and powdered milk, on the other, in that there is an inherent difficulty with making cheese and butter from non-kosher milk, whereas one can easily powder any milk. (This is precisely Dr. Levy’s question I mentioned above.) Thus, one could argue that the leniency that applies to cheese and butter should not apply to milk powder.
However, Rav Frank quotes the Ritva (Avodah Zarah 35b) who pointed out that, technically, one could make cheese even from non-kosher species, but the cheese yield from these milks is very poor, and when the milk curds, most of it becomes whey. Thus, although it is theoretically possible to make cheese or butter from non-kosher milk, the halacha does not require one to be concerned about this. Rather, one may assume that a gentile would not adulterate this milk. It is indeed noteworthy that while researching milk and cheese made the world over, I discovered cheeses made from the milk of cows, sheep, goats, water buffalo and yak, all of them kosher species, and milk used from non-kosher mammals such as donkeys, mares, llamas and camels, but I found not a single populace making any variety of cheese from the non-kosher milk. Thus, although the Ritva attests that it could be done, it is simply not worthwhile.
Rav Frank concludes that what permits the unsupervised milk used in cheese and butter is not that it is impossible to use non-kosher milk but that it is unlikely. Thus, he reasons, although one can powder non-kosher milk, the prohibition of chalav akum was limited to fluid milk and other products available in the days of Chazal which could be made easily from non-kosher milk. Since powdered milk did not exist in the days of Chazal, and since we are certain that standardly available powdered milk is of bovine origin, the prohibition against chalav akum does not apply to milk powder, just as it does not apply to butter and cheese.
We should note that the Chazon Ish took strong issue with Rav Frank’s position treating milk powder differently from fluid milk. The Chazon Ish contends that the lenience that applies to cheese and butter applies only because these products, inherently, are not made from non-kosher milk, a logic that does not apply to milk powder.
Thus, Dr. Levy’s friends who keep chalav Yisrael but use foods made with non-chalav Yisrael powdered milk follow the conclusion of Rav Pesach Frank, whereas those who are strict regarding milk powder follow the Chazon Ish’s approach. In Eretz Yisrael, this has become one of the major defining factors for the difference between what is called mehadrin (stricter) kashrus standard, and non-mehadrin hechsherim. The regular hechsherim allow use of non-chalav Yisrael milk powder (imported from the United States), whereas the mehadrin hechsherim use only chalav Yisrael products. (By the way, no Eretz Yisrael hechsher allows the use of unsupervised fluid milk as kosher; all hechsherim, both mehadrin and non-mehadrin, have accepted the position of the Chasam Sofer.)