Some soaps include ingredients derived from non-Kosher sources. Is there any reason not to use such soaps for washing Kosher food utensils?
The particular question posed to HaRav Moshe Feinstein indicated that the detergent contained alcohol derived from the by-product of non-Kosher food production. Rav Moshe rules that he can see no problem at all. He explains that such alcohol may even be used in the first instance to manufacture Kosher dish detergent.
Furthermore he rules that one may even process this prohibited food to alter it from a non-K to a Kosher product in order to be used in Kosher detergent. One may have thought that this is not permitted since we are not permitted to nullify prohibited foods thereby making them Kosher. Although non-K foods will become Kosher by being insignificant in various circumstances, for example if their presence in a mixture is less than one part to 60, we are nevertheless not permitted to arrange such nullification. That being the case one might think it ought to be prohibited to manufacture Kosher foods from non-Kosher foods since it is akin to nullifying the non-K to make it Kosher.
Reb Moshe proves that this is not correct from the Halacha that chickens incubated from non-K chicken eggs (having been laid by chickens that are Tereifos) are Kosher. So, although the eggs are not Kosher, the chickens hatched from them are Kosher. The reason for this is that the egg becomes inedible before its transformation to a new edible product. Not only are such chickens Kosher but we are permitted in the first instance to incubate such eggs as a commercial enterprise. [They may not be incubated in a domestic situation due to a Rabbinic decree to prevent the risk of inadvertently eating these non-K eggs.]
Neither is there a problem due to AchSheVei, which is the Halacha that a person can consciously promote non-foods to a food status by using it as a food [Rosh Pesachim daf 21; GRA & Magen Avraham 442; "AchSheVey - it has been made substantial"] as we that during Pesach we permit a scribe to write with ink that contains Chomets, notwithstanding the fact that it is expected that the scribe will suck on the pen and ingest some of the Chomets ink. We are not concerned about the Chomets since, a) the ink is not food; b) the scribe has not consciously chosen to eat the ink. It is not AchSheVei, considered a food unless the scribe chooses to use the ink as a regular food.
The position of the NoDah BiYeHuDah is even more surprising. He restricts the Halachic definition of food to those products that are used as a food in themselves. Products that are exclusively used as an adjunct to be used with other foods, are not foods. He limits AchSheVei to products that are chosen to be consumed in their present form and therefore permits [YD 2-57] using a food additive derived from non-kosher since it is in itself not an edible product.