I was just on vacation in Vermont and picked up some whey butter from a cheesemaker I visited. They label it as "old fashioned" but I clearly understand it to be the economic use of a byproduct (recycling, if you will). In trying to find out more, I'm finding that perhaps more butter today may be whey based rather than sweet cream based. So my husband and I collectively wonder the following things:
How does the fat content differ? I found on one site that whey butter is 82% butterfat, but where's that all coming from? Is whey that high in fat, or is it additionally combined with cream?
How does it differ for baking and sauteeing? Does it have the same solids that brown for brown butter?
Are there still more bases for making butter beside whey or cream?
What is "old fashioned" about the whey butter? Where and when was it made from whey?
Finally, is there much more whey butter on the market than I would have formerly assumed?