What is whey?
It is lactoserum WITHOUT lactose... Id est protein from milk without casein.
The best whey protein is the fresh lactoserum from raw milk grassfed mammals cheese production that you fermented to reduce lactose content.
When this is not available can you get a good whey protein?
It is a very difficult question because of the different methods of separation of whey protein from whole milk.
Secondly even if whey protein do not contain caseins the tolerance of whey protein from different mammals is not the same.
Goat or sheep whey is better tolerated by humans and children.
Unfortunately brand products available are of unknown or cow origin.
Last but not least the techniques of separation do not lead to the same products and the same alteration.
Trends in whey protein fractionation