Babies cannot take the milk that is dried by evaporation except after mixing the milk with enough water. Usually, the amount of added water exceeds the composition of milk and changes its properties, and hence prohibition can’t be legally proved here by taking such milk.
Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee, states the following: According to the Qur’an and the Sunnah, the prohibition to marry certain women because of nursing occurs in the two years of nursing, but scholars differ as regards the number of times a child must suckle for the prohibition of marriage to become certain. If milk in its liquid state is taken from a known woman and given to a known child, prohibition will then be certain. But in case the nursing woman or the suckling child is unknown, prohibition will not be proved, even if there is some doubt, because the original state is the absence of doubt.
What if the milk of more than one woman is mixed and a nursling is given it? Will prohibition be proved in such case? In some countries, something called a milk bank was established, just like a blood bank. Scholars were divided into two groups as regards its judgment: The first group preferred precaution and said that it is impermissible to nourish babies from such milk, as this might result in a brother marrying his sister or his mother (that is, because of nursing) unawares. As for the second group, they did not find any cause for impermissibility and asserting prohibition, which is not proved except if the mother from whom the milk has been taken is known for certain. Although not knowing the mother does not prove prohibition, it is considered precautionary not to use such milk.
In this regard, Sheikh Ahmad Haridi, the former mufti of Egypt, issued a fatwa in 1963, explaining that using this collected milk in milk banks as nourishment does not prove prohibition. The text of this fatwa included the following:
There is a process in which milk is dried by evaporation becoming a dried powder, which babies cannot take except after its being mixed with enough water to dissolve it. This amount of water exceeds the composition of milk and changes its properties becoming the most of it. By applying the judgments we mentioned, we conclude that prohibition is not legally proved by taking this milk. Sheikh Haridi deduced the above judgment after citing many opinions of Hanafi scholars and interpreting their rules. The illustration of this issue is in the first volume of the Encyclopedia entitled, “Al-`Usrah Tahta Ri`ayat Al-Islam.”