Here is a pic of a 1 gallon raw milk loaf (on the left) compared to a two gallon store bought whole milk loaf. The raw milk loaf has only been aging for a day at this point, while the whole milk had been aging for three days.
Notice how bright yellow the raw milk is. The natural beta careotene is preserved unlike store bought milk, and, even though it had a ton of cream on top, it isn't collapsing in on itself like the store bought. Those bulged sides? Yeah, I didn't do that on purpose, the loaf did that itself.
I suspect the main problem with store bought whole milk is the amount of moisture that is emulsified with the far and cream. Since it is emulsified really, really well (i.e., homogenization) and the fat droplets never fall out of suspension (even in a press), store bought whole milk is entirely unsuitable for home cheesemaking. I will never use it again for hard cheese--the loaves are unattractive, it never gels as well as raw/2%/1%/skim, and I can't taste any advantages to it either. But on that last note, when I have the next tasting party I'll get more unbiased opinions.
Cheese A Day by Jeremy Pickett is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.
Based on a work at cheeseaday.blogspot.com.