What it is and where it comes from
Whey is the liquid left after milk is turned into cheese. Most whey comes from cheese set with rennet; acid whey comes from Greek yoghurt or cheese set with acid. It is dried into whey powder or filtered into whey protein. Since most rennet today is microbial, most whey is not from animal rennet, but you cannot tell from the label.
What scholars say
- Whey from cheese made with microbial or vegetable rennet, or from acid curdling: halal for all.
- Whey from cheese made with animal rennet from animals not slaughtered in the halal way follows the rennet disagreement: Abu Hanifa held such rennet pure, most other scholars do not. See rennet.
Where you find it
Protein powders and bars, biscuits, chocolate, crisps, bread, sauces, baby formula and ready meals.
What to look for on the label
For protein powder, look for a halal logo: many large brands are certified. Check flavoured powders too, since flavourings can contain alcohol or gelatin.
This is a guide, not a fatwa. Recipes change, so check the label, look for halal certification, and ask your local imam where scholars differ.