This is a mini-project looking at sweet and sour flavors, sponsored by PAMA Pomegranate Liqueur.
Sour tastes are mostly produced by acids, including citric acid from fruits and acetic acid from vinegar.
As with sweetness, the taste receptors for sourness are found on the taste buds on our tongues, and our initial reactions to them at birth are hard-wired. But unlike sweetness and like bitterness, we have an inherently negative natural reaction toward sourness.
Evolutionarily this makes sense. Fruits are acidic both when they're unripe and when they're spoiled. But when they're ripe, the sourness is in balanced with sweetness so we innately know that the food is probably safe to eat and will provide us with lots of energy.
Extremely sour/acidic things can be harmful; high-acid substances activate pain nerves in the mouth and irritate it. So our awareness of sour can be a pre-indicator that pain is coming, must like our taste for bitter warns us of possible poison.
However, us humans tend to like a small amount of sourness in some foods, and in combination with sweetness we love sourness, from Sour Patch Kids candy as children to lemonade and Lemon Drops as adults.
And of course in cocktails, the balance between sweet and sour is a crucial factor.
(Much of this information comes from the book Taste Matters.)
One great thing about sour tastes is that we can easily know how sour they are by using a pH scale. The best one of these I've seen done in the cocktail world was by Michael Lazar of Hog & Rocks and HiLo BBQ, who measured the pH of about 80 drink ingredients in this great blog post. Follow the link to see the full chart.
These are some of his conclusions:
- Common cocktail ingredients range from neutral (e.g. gins and sugar syrups) to distinctly acidic (e.g. citrus juices). They are not often alkaline.
- The most acidic ingredients are, unsurprisingly, lemon and lime juices which measure below PH 3.0.
- The next most sour ingredients after citrus are vermouths, sherries, and madeiras: non-distilled products, all based on grapes.
- Distilled spirits which start life or are sold at high proof (i.e. are highly distilled) and which spend no time in wood are pretty much neutral.
- Spirits which are aged in wood appear to develop acidity over time (so their pH gets lower).
Stephen Shellenberger also has some spirits pH observations based on original research and analysis of a research paper. This food-oriented website also has a big list of pH levels of various ingredients including liquids but also solids like parsnips.
Next we'll look at measuring sweetness and what happens when you combine sweet and sour things together.