Just the other day I cooked up some ground beef from Trader Joe's that was obviously adulterated About 40 years ago when I was a kid the local butcher would li

Just the other day I cooked up some ground beef from Trader Joe's that was obviously adulterated About 40 years ago when I was a kid the local butcher would literally grind the beef in front of you while you waited. A lot harder to adulterate something when it's prepared on the spot. I don't see that done any more, but maybe I'm just not shopping in the right stores. I live in suburbia; it's probably easier to find an authentic butcher shop in a real city. Edit: I don't know the source of Trader Joe's particular ground beef. But I once saw a show on TV about how hamburger patties are made: There have a giant tray (hundreds of pounds) of relatively lean beef, and next to it a giant tray of trimmings (mostly fat). They grind and mix these in proportion to the desired leanness of the final product. Hamburger meat can be purchased in various grades which differ in fat content. Unfortunately, none of that could explain what happened to you, unless maybe some of the fat mixed in to your hamburger meat was rancid?