When you make kefir that ferments for too long it separates into a white and clear liquid part. Is the clear liquid part what they sell in stores as whey protein? Is there any benefit in consuming this clear liquid?
The clear liquid part is whey. But that’s different from what they sell in stores as “whey protein”. The stuff that they sell in stores is actually “whey protein concentrate” (or “whey protein isolate”) and it’s made by concentrating the protein that’s found in liquid whey. The actual liquid whey itself is quite low in protein before it is processed. Only about \~12.7% of the calories in liquid whey are from protein. Whereas whey protein concentrate is usually >70% protein.
You can see the nutrition info for liquid whey here: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170885/nutrients