Coffee and Acidity - Why Does Coffee Taste Sour? Is Slight Sourness in Coffee a Sign of Spoilage?

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Understanding Coffee Acidity: From Beginner to Enthusiast

For many beginners, the acidity in coffee can be somewhat difficult to accept... When coffee flavor mixes with acidity, doesn't it feel strange?

As someone who loves intensely acidic coffee that could "kill people without consequence," I always find the acidity wonderful and delightful, completely ignoring the voices of beginners. How sinful of me.

Today, let's thoroughly explore the relationship between coffee and fruit acidity, allowing you to experience the joy of acidity and mouth-watering pleasure when drinking acidic coffee.

1. The Source of Acidity: Coffee Cherry Fruit

I think many people don't even know that coffee originally grows looking like this—like cherries, shiny and appetizing.

The seeds inside the red pulp become green coffee beans after processing. At this stage, the beans are green, like seeds of ordinary plants. They need to be roasted to turn coffee-colored or black, becoming the roasted coffee beans sold in markets.

Anyone who has studied basic biology knows that the purpose of fruit pulp is to provide nutrients for the seeds. Therefore, during cultivation, the original flavor of the pulp naturally affects the flavor of the coffee beans.

So first, understand that it's perfectly reasonable for coffee to have fruit acidity—in fact, this is the truly natural state. It's definitely not spoilage or sour rottenness.

After understanding that acidity itself isn't a "sin," try to let go of your stereotypes about acidity. (Stereotypes are the biggest bottleneck preventing learning new things.)

2. The Possibilities of Acidity: Pleasant vs. Unpleasant Acidity

Although acidity is normal, it's not just about being acidic. Due to various factors including the coffee beans themselves, processing methods, transportation, storage, roasting, and brewing, acidity can be divided into delicious acidity, pleasant acidity, or unpleasant acidity, bad acidity.

When drinking coffee, calmly tasting, imagining, and comparing the acidity within is an important process in learning about specialty coffee.

Pleasant acidity includes: malic acid, citric acid, grapefruit acid, passion fruit acid, red wine acid, berry acid, cherry acid, citrus acid, peach acid, pineapple acid, black vinegar, red vinegar, etc.

Imagine the natural and characteristic fruit acidity presenting itself in your mouth, enriching the layers of the coffee itself, yet being gentle and not overly stimulating.

Unpleasant acidity includes: overly strong vinegar acidity, rotten acidity (expired), over-fermented acidity, stuffy acidity, lactic acid (sweaty acidity), decayed acidity, etc.

Just imagining these acids in coffee feels uncomfortable. Moreover, unpleasant acids are highly recognizable—even a small amount can ruin the entire cup of coffee. This is probably the main reason why people generally have bad impressions of acidity.

But pay special attention: truly specialty-grade coffee basically doesn't contain unpleasant acidity. These acids significantly affect mouthfeel and can't even meet the threshold for specialty coffee.

So when drinking bad coffee and encountering unpleasant acidity, please don't blame specialty coffee. After all, there are too many irresponsible merchants nowadays. To protect your palate from contamination, stick to guaranteed specialty coffee.

3. Choose Growing Regions and Roast Levels with Medium Acidity

When you're not yet accustomed to drinking acidic coffee, it's recommended not to completely avoid fruit acidity. Instead, choose beans with medium or lower acidity to let your palate gradually adapt to the diverse fruit acids.

In terms of growing regions: African beans generally have higher acidity, Central and South American beans have moderate acidity, and Asian beans have lower acidity.

However, the above is just a basic classification. Because the terroir conditions of specialty coffee vary greatly now, even different regions and estates within the same country can have different acidity levels. So when buying or ordering single-origin coffee, asking clearly is the most direct approach.

In terms of roast level, as the degree of roasting increases, acidity becomes less obvious. Therefore, choosing medium roast or above is relatively safe. For beginners, trying medium-roasted or darker beans from regions that aren't particularly acidic is an excellent choice.

For example, FrontStreet Coffee's Sumatra Yellow Mandheling and Honduras both have lower acidity, while Guatemala, Natural Sidamo Flower Champion, and Brazil Queen Estate are medium-acidity beans that use low acidity to balance complexity, making them very suitable for beginners not accustomed to acidity.

If you find medium roast acidity acceptable and can appreciate the taste pleasure brought by good acidity, you can gradually explore further.

Choose different options to balance acidity and gradually let yourself fall in love with wonderful fruit acids.

For example, FrontStreet Coffee's light-roasted Costa Rica Black Honey, Panama Geisha Butterfly, or medium-roasted Yirgacheffe Buna Ababa are all representatives with slightly more acidity but still delicious.

4. Adjusting Acidity Through Brewing

Regardless of the equipment, in principle, minor adjustments can still reduce acidity, balancing acidity with body and sweetness to your preferred ratio. In fact, this could be called the core concept of brewing.

Several variables that affect acidity include:

♥ Temperature: Higher temperatures result in significantly lower acidity, but don't overdo it. General extraction is around 90-92°C. Raising it to 95°C will significantly reduce acidity.

♦ Grind size: With finer grind, acidity is less obvious; with coarser grind, acidity is more obvious. So you can adjust slightly finer to reduce the overall acidity.

♣ Water amount: Water amount doesn't have much to do with extraction, but with slightly more water, acidity is less obvious while sweetness is enhanced. Therefore, you can add 20-50cc more water.

♠ Time: In principle, this concept is similar to grind size. Shorter time results in more obvious acidity, longer time results in less obvious acidity, but don't exaggerate. Over-extraction will still result in bitterness.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473