Buying ready made hamburger in patties and rolls is like playing russian roulette with 3 shells in the chamber.
The New Yorker did an expose on the practice of using fat and crud trimming from cattle that used to go in dog food. Now they treat it with ammonia under pressure and defat it, killing the e-coli [mostly! sometimes] and using it to fake reduce the fat level in the burgers. Toxic waste at its worst.
You can be sure taco-burp is using this devils concoction.