Anyway, hamburger went from $.29/lb. to $.79/lb. For a grocery budget that was on average $15.00/week, this was astronomical. (Other meat prices increased the same way, not just ground beef.)
So, the major chains started offering cheaper hamburger with soy protein in it to extend it. It made the meat smell rather sour, and was a peculiar gray color. This lasted until Reagan was elected.
I hope someone from the Midwest who remembers this event will explain further.