Science lesson!
Now it’s time for some serious science discussion! And nothing is more pressing of a concern in the world of science than the acidity of coffee.
While the acid found in coffee can cause some unpleasant stomach experiences for some coffee drinkers, today we will mostly be focused on acid and its role in conspiring to create an advanced flavor palette.
Thus, for today’s lesson we will be discussing the role of acid and the chemistry behind coffee. Keep in mind this will be on the test, so take notes. (note: there will be no test…but still maybe take some notes).
What is acid?
To begin our chemistry lesson, acid, broadly speaking is a chemical substance that possesses a sour, sorta pungent taste. Emphasis more on sour, but the burning feeling has some traits of a pungent flavor, too. Acid means, “sour” in Latin, which explains why acid is well, sour tasting.
Many may also point out that acid sorta burns depending on how strong it is. This can be good or very bad considering what sorta acid we are dealing with. luckily, coffee’s acid isn’t the kind that can melt your face or hard substances! Or at least not the way we brew ours it can’t. On a pH scale, liquids that score a 7 or lower are highly acidic and nothing to mess with!
Acid does occur naturally, so have no fear of acids in your food, especially with coffee. In which case there is coffee acidity and coffee acid, now these are different, let’s see how.
Coffee acid
Coffee acid refers to the naturally occurring chemical processes in the coffee plant that are actually beneficial to our health. They can cause some heartburn and indigestion for some coffee drinkers, but are otherwise safe and health enhancing to consume.
These acids can have a bit of a subtle taste and are even more muted in dark roasted coffee beans because the acids break down during the roasting process. This is why light roasts are highly acidic and darks, well, aren’t.
Chlorogenic acid is one type of acid that occurs naturally in coffee plants. Some of the health benefits include reduced inflammation and lower blood pressure. Quinic acid is a colorful little acid that contributes to the acidity and astringent taste of coffee.
Caffeic acid allows the coffee plant to practice better photosynthesis, allowing it to absorb energy from the sun. This interesting acid won’t do the same to us, of course, but some studies have been conducted to see what the effects of caffeic acid on cancer are.
Coffee acidity
Now this refers to the pH scale that coffee exhibits, rather than the actual acid compounds found in coffee. The pH or “potential of hydrogen” scale runs from 0-14 and is divided into acidic and alkaline liquids.
Anything lower than 7 on the pH scale is acidic, and guess where coffee ends up? Coffee is usually around 4.3-5 degrees on the pH scale. This marks it as acidic but nothing too insanely acidic. The human body, however is a 7.4 on the pH scale, and anything lower than our acidity level can cause digestion problems like heartburn.
Hence why some individuals have an unpleasant physical reaction when drinking coffee. In order to influence coffee’s acidity, two major things play a role. They are the elevation of the coffee plants while they are growing, and then later on in the coffee process, how much they have been roasted.
Elevation
Coffee plants that grow at higher elevations are almost always, with few exceptions, higher quality coffee beans. The examples abound, but it can be said that plants that have been grown at an altitude lower than 4,500 feet are less acidic than plants cultivated at higher elevations and often times of lower flavor and character quality.
So we can already begin to see that acidity in our coffee can certainly be a good thing. Whether the soil is volcanic or not plays a role too, because volcanic soil can alter the pH of the land. High acidity equals higher fruity and sweet flavors. This is why coffee grown lower to the ground can sometimes taste a bit, well, bland in comparison to its high up cousins.
So for those seeking complex flavor palettes including sweet, fruity and spicy, try to seek out coffee that is high in acidity or that comes from higher altitudes. These two traits are intertwined.
Roasting levels
Now, let’s say our coffee was grown way up high, like some of these fancy and high end coffee beans. But, the roasting profile is a dark roast.
Does this mean your coffee will be more or less acidic.
That’s a tough one since so many variables come into play with coffee, things like chemical reactions and other sciences. But generally speaking, yes, the darker roasted your beans are, the less acidic they will most likely end up.
Roasting can change a bean in many more ways than just acidity. Some suggest the caffeine content as well as the bean’s flavor complexity also become diminished the darker a bean is roasted.
So for those who want to try and preserve the acidity of their beans and potentially some of the caffeine and the nuanced and advanced flavor profile your beans may have, go for a light or medium roast.
Fun with acid
Now, because acids can occur naturally in other types of foods, when cupping or trying coffee these other fruits and flavors can also make guest appearances, too. And here’s where the fun begins.
Because coffee can be a little different in its pH levels, so too can the acids that occur in the coffee taste a bit different, too. To be clear, your coffee will most likely not taste exactly like many of these fruits as listed below. But it will have a level of acidity that is akin to and reminiscent of these fruits.
So, when a coffee is at the same pH balance as watermelon, that isn’t to say that your espresso is watermelon flavored! (though that would be interesting). It means instead that the level of acidity you will experience is about on par with a watermelon.
So, let us see some of these acid pairings, shall we? Cold brews, for example, have a bit lower acidity, ranking more around 6 or 7 on a pH scale. This unlocks acidity akin to melons, dates or papaya. Sounds fruity right? Well that’s just the beginning.
Espresso often times lands at around 4 on the pH scale and so espresso has the potential to have an acidity profile that can be reminiscent of grapes, peaches, plums and even pineapple.
Any coffee that is brewed and lands anywhere from 3-4 on the pH scale can induce an acidity reminiscent of grapefruit, apples, oranges and raspberries. 2-3 will yield an acidity profile like cranberries, gooseberries and strawberries.
And in the possibility that you somehow happen to attain coffee than is on a 1-2 scale, expect lemon or lime levels of deep and intense acidity. Though these last few scales are a bit rarer to experience if at all in coffee, and so finding a coffee bean that is as acidic as lemon may be a science project all its own.
The wonderful world of acid
Can you imagine a world without acid? Well luckily we will never need to, we hope! Acid plays a big role in the flavors and their complexity that you will find in your coffee.
And remember, acid isn’t a scary or bad thing, in fact many of the highest quality coffee beans are highly acidic in nature and have an advanced and unique flavor palette to offer us.
So, there is no time like the present, get out there and put these science lessons to practical use!
Drink more coffee and perhaps give more acidic coffees a try and see if they are for you! And wear your science safety goggles when brewing (note: don’t actually do that!).
Sources:
l “Acid in Coffee.” EatCultured, 13 Mar. 2018, eatcultured.com/blogs/our-awesome-blog/acid-in-coffee.
l Perfect Daily Grind. “Coffee Science: What’s Acidity?” Perfect Daily Grind, 26 Feb. 2018, http://www.perfectdailygrind.com/2015/11/coffee-science-whats-acidity/.
