Yes, if used correctly. As an acid, vinegar breaks down the tough protein fibers and connective tissues in meat. This is why it is a staple in marinades. However, leaving meat in vinegar for too long can actually make it mushy or even tougher as the proteins over-coagulate. Limit marinating time to 2–4 hours for chicken/pork and up to 6 hours for tougher cuts of beef and turn the meat every hour to completely marinade it..