We mean plain, unflavored yogurt. Usually Danon or store brand. I don't think Yoplait makes plain yogurt but you'll find them all in the same are of the supermarket. The enzymes, acids and live active cultures in yogurt and buttermilk break down the protiens and connective tissue of meat, tenderizing it. Whatever spices you add to them ride along with them flavoring the meat along the way.
If you have Italian dressing(gotta be Wishbone), L&P worcestershire sauce and Tony's......You don't be needin nuttin else! Oh and for the beer marinade....use the above ingredients while drinking the beer.
I like your beer marinade. We use the Italian dressing trick with wild turkeys. They are smaller than the storebought kind and can be tough. But the dressing does it well.