I'm doing a mini-project looking at sweet and sour flavors, sponsored by PAMA Pomegranate Liqueur.
The sweet-to-sour balance in a cocktail is crucial. I like Sam Ross' quote about it: “The sweet and sour elements in a cocktail are like the pieces of bread in a sandwich. If they’re not in balance, the whole thing falls apart.”
I'm going to look at sweet and sour (plus the other basic tastes) separately, then at how they interact.
We all know by now that at least sweet, sour, salty, and bitter are four basic tastes, with others proposed including umami and fat. (Apparently metallic and astringent were proposed as tastes at one point but now they're considered derived from odors and tactile sensations instead.) There are receptors for the basic tastes on our taste buds, so they're hard-wired on our tongue.
You probably know that the "tongue map" of where we taste certain things on different parts of our tongue is wrong; we can sense all of the basic tastes anywhere that taste buds are present, though our sensitivity to certain tastes can vary across different places on the tongue.
One cool thing about the basic tastes is that unlike odors, they do not combine together to form new tastes. So having something sweet and something sour to balance it does not form a new taste (swour?).
However, and importantly to this research project, different tastes suppress each other when they're combined. To diminish the sensation of bitterness, for example, we can add salt to food or drink. Sour flavors on their own are unpleasant, but in the context of sweetness we perceive them as good. (This makes sense if you think about ripening fruit - at some point a very tart apple becomes sweet-tart, signifying to us humans that it is ripe and ready to eat.)
Likewise, a sweet-and-sour cocktail like a Daiquiri is both sweet and sour (not swour), but when we get the balance right we don't perceive the drink as being too sweet or too sour. We perceive it as being balanced.
(Much of the above information comes from the book Taste Matters. )
In the next posts on this project, I'll study sweetness and sourness as separate concepts, then we'll get back to combining them as we do in cocktails.