What could be the basic ingredients that potentiate sourness and bitterness? 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?
About any acid will deliver a sour taste from H+, along with whatever taste the corresponding anion brings along.
Most alkaloids are bitter.The term covers a wide range of different chemicals, mostly including nitrogen qnd oxygen as part of their structure. There are likely quite a few bitter compounds which are not alkaloids, but none spring to mind at the moment. Bitter is a far more complex response than sour or sweet.