Raw foods contain organic acids such as ascorbic acid (Vitamin C), citric acid , lactic acid, etc. I feel better overcooking my vegetables to destroy the organic acids. Really cook the crap out of them without turning them completely black. I cook green leafy veges in the oven until the are dry as a bone. My body loves it.
Lemon, lime, apple cider vinegar are horrible for people who have trouble metabolizing acids. They may be alkalizing for some, but harmful to others.