Sweet Versus Sour: Understanding and Measuring Sourness
December 18, 2013
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.
This post about sweet and sour is sponsored by PAMA, a pomegranate liqueur with a unique balance of sweet-to-tart you can read more about on the PAMAPros.com website. Follow @PAMAPros on Twitter!
the pH scale can really only tell you so much and most wine analysis is done in terms of g/L of acids. that chart with all its pHs definitely does not order them by perceived dryness. it still won't compare well when we only look at a similar set like only dry white wines. because the major acids within the wine (malic, tartaric, lactic) have different effects on pH. things get screwy when you look at buffering as well. I think that the chinaco bianco in the chart has such a low pH because it has unbuffered fatty acids. so its ratio of total acids to pH is really skewed relative to the other spirits in the chart. but I don't know how to explain every what-if of this stuff yet.
eventually we are concerned with perceived acidity so we have to understand the major factors effecting perception. the big variable to add to the acid/brix ratio is aroma intensity or extract (http://www.northwest-wine.com/Balance-in-Wine.php).
we do a lot of manipulating of this variable in cocktails by using an aromatic sugar as opposed to bleached white, or by adding bitters, particularly orange bitters or peychaud's. for people whom a sour drink is an acquired taste, their aversion is primarily to hollow, 'sweet-tart' sour drinks. if you keep the same brix/acid ratio but increase the extract, they are more likely to enjoy it.
Posted by: stephen | December 19, 2013 at 08:52 AM
Very interesting as always, Stephen. I look forward to the day when I have a refractometer and hydrometer to add my to my equipment!
I should shop around for the refractometer - they don't look that expensive but I don't really know what I'm looking for in cocktail applications.
That's a project for another day but if you happen to own one that you like please let me know! Cheers.
Posted by: Camper English | December 24, 2013 at 04:28 PM