Scientifically, an “acid” refers to a solution lower than a seven on the pH scale, which measures acidity and alkalinity. Vinegar has a very low pH, around two or three depending on the variety, and tastes very acidic. But when it comes to cooking and your tastebuds, the experience is more complex than only this number on a scale. Of the five taste sensations — sweet, sour, salty, bitter, and umami — scientific acids often fall under “sour,” but not all low-pH foods will make your mouth pucker. Tomatoes, for instance, are acidic on the pH scale, but the taste is more sweet than sour. In cooking, “acids” mean ingredients whose sharp sourness is prominent, and when you’re looking to add complexity to a dish, acids are a good place to start.
Cooking is often about finding a balance between these basic taste sensations, which is why apple cider vinegar can be exactly what you need to make your pot of chili a little brighter. Acids enhance the salty, umami-rich flavors already present in chili, and round out the sweetness, adding intricacy to the dish. Apple cider vinegar is versatile with a light, fruity flavor, but red wine and balsamic vinegar are both good choices for heavier chilis that need something bolder.
The vinegar isn’t there to be the star of the show, which is why you stick to about 1 tablespoon, but it will shine a sharp spotlight on and complement the existing components. The secret to perfect chili is a balance of flavors.