Origin Story of Sun-Dried Yirgacheffe Autumn Cherry Coffee Beans - How Does Sun-Dried Yirgacheffe Autumn Cherry Taste?

FrontStreet Coffee: An Introduction to Coffee Acidity

The way I see it, coffee acidity divides into good acidity and bad acidity. People who drink coffee often will notice that good acidity always comes accompanied by sweetness, while bad acidity carries almost no sweetness, forming a sharp, stimulating, harsh sourness.

From this it follows that sweetness is the foundation of a delicious cup. Never mind flavor, mouthfeel, or aftertaste—without sweetness, the cup will definitely be unpleasant to drink.

Try adding a little lemon juice to sugar water and taste it. Doesn't the whole cup suddenly gain layers and brightness? That is the enormous impact acidity has on sweetness. When we say a coffee tastes sweet and delicious, we are really saying its acidity is of high quality and easy to accept.

So where does coffee's acidity come from?

In green bean form, coffee contains chlorogenic acid, citric acid, and malic acid. Roasting creates quinic acid, caffeic acid, acetic acid, and other low-molecular-weight organic acids—all representative acidic substances in coffee. There are also high-molecular-weight organic acids such as fatty acids, and inorganic acids like phosphoric acid. The intensity of coffee's acidity depends on the total amount of these organic acids and the accompanying pH value.

After roasting begins, the sucrose in the green beans starts to decompose, which raises the content of organic acids. At light to medium roast levels, acidity keeps building toward its peak. Past that peak, continued roasting causes the acids to volatilize and break down—their content drops sharply and perceived acidity falls with it. This is why dark-roasted beans rarely taste acidic.

Although caffeic acid and chlorogenic acid make up a considerable share of coffee's acids, the sensations they bring are mostly bitterness and astringency. The remaining organic acids in coffee are largely the same acidic substances found in fruit—which is why we often taste fruity flavors in coffee.

Malic acid tastes like a ripe apple: soft, restrained acidity with a hint of sweetness. Citric acid takes its name from the citron fruit and brings classic citrus acidity. Acetic acid is a double-edged sword: at high concentrations it produces a sharp, pungent sensation, but at low concentrations it improves the texture of coffee's acidity and, together with other acids, gives it richness. Phosphoric acid is the easiest acid to perceive, with a very bright, lively character—the berry-like acidity we often find in Kenyan coffee is actually the brightness of phosphoric acid. Quinic acid was first discovered in cinchona trees and is also found at high concentrations in kiwifruit; in coffee it recalls the acidity of kiwi and passion fruit.

Knowledge point: Like fruit, coffee holds several different organic acids at once, and their particular combinations—types and proportions—create coffee's (or a fruit's) unique acidity. That is the source of "acidity" in coffee.

FrontStreet Coffee Recommendation

To taste "good acidity" in action, start with the FrontStreet washed Yirgacheffe. Yirgacheffe is a small town in southern Ethiopia's Sidamo province at roughly 1700-2100 meters, with coffee planted above 1800 meters—among the highest coffee elevations in the world. Its beans are famous for a white floral aroma and crisp lemon-citrus acidity, and the cup is light, elegant, and tea-like: clean lemon tea, with sweetness supporting every note of acid.

If you prefer acidity wrapped in fruit sweetness, the FrontStreet natural Red Cherry Yirgacheffe uses only fully ripe cherries, dried whole on raised beds and turned every 2-3 hours at the start to prevent uneven fermentation. Three to five weeks of sun-drying give it citrus-like acidity with berry juiciness, honeyed sweetness, and creamy smoothness. To brew either one: use a V60 at 90-91 degrees C, 15g of coffee at a 1:15 water ratio, ground to fine-granulated-sugar size (80% pass on a #20 sieve). Pour 30g to bloom for 30 seconds, then pour to 125g by about 1 minute, and finish with the remaining 100g by around 1:35; drawdown completes at 2:00-2:10.