Rennet is an enzyme used in the food industry for the preparation of cheese by curdling milk. It coagulates the milk, causing it to separate into solids (curds) and liquid (whey). Rennet is extracted from the stomach of an animal whose meat is lawful after slaughtering in accordance with Islamic Law. Whey is a by-product which appears during the process of cheese making.
Regarding the whey and rennet of animals which were slaughtered according to the Islamic law, then it is unanimously considered permissible for consumption.
As for the whey and rennet of animals which were not slaughtered according to the Islamic law, scholars hold two opinions:
- It is pure; held by Imam Abu Hanifah, including one saying of Imam Ahmad and others.
- It is impure; held by Imam Malik, the two students of Imam Abu Hanifah [Abu Yusuf and Muhammad ibn ash-Shaybani] Imam al-Shafi`i, another opinion of Imam Ahmad and others.
Al-Mabsoot, a Hanafi reference, states: “Cheese is permissible to consume even if it is made by Zoroastrians (polytheists of Persia who used to worship fire) because it is narrated that a servant of Salman al-Farisi, when he was a governor of al-Mada’in, brought him a basket full of cheese along with some bread and a knife. Salman al-Farisi would cut pieces of the cheese and hand it out to his companions and would explain to them how cheese is made.”
The Maliki reference, Manh al-Jaleel says that “Imam Malik disliked cheese because it was made by rennet of animals that are not slaughtered according to the Islamic Law (maitah).”
In Sharh al-Bahja, a Shafi’i reference, it states that “cheese is allowed as long as the rennet is obtained from a properly slaughtered halal animal that is only feeding on milk, otherwise the contents of its stomach are najis (impure).”
Kashaaf al Qinaa’, in Hanbali fiqh states that “the cheese of the Zoroastrians and other polytheists is allowed even if it is made from rennet of animals they slaughtered. Which means that the cheese made by the People of the Book (Jews and the Christians) is also allowed.”