When it comes to basic tastes (saltiness, sweetness, bitterness, sourness, and umami), I can easily think of very basic ingredients that could be considered the essence of a given taste, something that you can add to any meal and potentiate that specific taste:
- For sweetness, we have sugar.
- For saltiness, we have salt.
- For umami, we have monosodium glutamate.
I have doubts regarding sourness. At first I thought about vinegar or lemon juice, but both ingredients do modify the flavor of meals you add them into (and not just potentiate a given taste). And regarding bitterness, I just have no clue. Note that I am speaking about ingredients (something you can find in a kitchen), and not about chemical compounds in general.
So what ingredients can be considered the essence of sourness and bitterness?