What Factors Influence Coffee Cleanliness? Understanding Clarity in Pour-Over Coffee

Understanding Coffee Cleanliness: What Makes a Coffee Bean "Clean"?

In our daily visits to coffee shops or when watching others taste and evaluate coffee in short videos, we often hear descriptions like "this is such a clean bean."

This naturally makes one wonder: what exactly is coffee cleanliness?

What does coffee cleanliness refer to? In our perception, the cleanliness of a liquid typically refers to its visual appearance—being clear, transparent, and free from impurities or contamination. Cloudiness and low transparency would be considered unclean.

The same principle applies to coffee, except that we need to translate the visual perception of cleanliness into a taste sensation—what we describe as coffee cleanliness. Therefore, it's certain that this "cleanliness" doesn't mean the coffee is tasteless; otherwise, people wouldn't express such astonishment when describing it. In fact, cleanliness in coffee refers to the absence of any negative flavors throughout the entire experience—from the first sip to the aftertaste—with distinct layers and clearly identifiable flavors. This is what cleanliness means in coffee.

For the general public, there's a general trend in flavor preferences. Negative flavors that people typically don't want to taste include bitterness, astringency, medicinal tastes, earthy flavors, and woody notes. Meanwhile, descriptors associated with delicious foods like citrus, berries, and sugars are the flavor types that people prefer.

Before coffee beans are processed into roasted beans, two main factors affect their quality—the higher the quality of the coffee beans, the higher the cleanliness of the coffee.

1. Harvesting

Today, it's common practice for specialty coffee beans to be harvested using fully ripe coffee cherries. However, in some regions, mechanical harvesting is necessary for large-scale collection, which inevitably includes unripe fruits. Unripe coffee beans have a special name—"quakers." Quakers are difficult to identify when they're raw green beans, as their color is very similar to beans from ripe fruits, but they show more obvious differences after roasting.

They are lighter in color than mature green beans and don't develop proper color during roasting. If these beans are mixed in, they will produce astringent flavors. But don't worry! Quakers, along with other defective beans like insect-damaged beans, shell beans, and roasted defect beans, are manually removed before roasting. After roasting, another selection process removes any roasted defects, so when you buy FrontStreet Coffee beans, you don't need to worry about purchasing products with defects.

2. Processing Method

People often say that washed beans are cleaner than natural-processed beans. This statement is both correct and incomplete. This is because the earliest natural processing involved simply drying coffee cherries and removing the husks, taking about half a month. During this waiting period, many unstable factors could occur, such as over-fermentation leading to spoilage or mold growth due to insufficient sunlight. These factors could result in numerous defects and off-flavors in the coffee beans, making them seem less clean compared to washed processing.

However, with the vigorous advancement of the specialty coffee wave, natural processing methods have become more refined. Natural-processed beans produced according to current standards can achieve the same high quality, low defect rate, and high cleanliness as washed beans. It's worth mentioning that cleanliness here doesn't refer to brighter acidity being cleaner. When people say washed beans are cleaner than natural-processed beans, they're referring to aspects like quality and flavor layer presentation. The equation "bright acidity = clean" is actually a common misconception.

Extraction and Cleanliness

Did you know? Cleanliness is linked to coffee concentration, and both over-extraction and under-extraction will affect it. What we often call "over-extraction" occurs when extraction is excessive, pulling out undesirable compounds and ultimately filling the entire cup with bitter, woody, and other unclean negative flavors. Under-extraction, on the other hand, means the aromatic substances in the coffee are insufficient to support the entire flavor profile, resulting in obvious hay-like negative flavors—another manifestation of uncleanliness.

Therefore, when brewing, it's important to control the extraction concentration to prevent over-extraction or under-extraction, which would affect the entire coffee experience. When brewing, there are two additional details worth paying attention to:

1. Excessive Fines

If the quality of the grinder is poor, it can easily lead to uneven grinding and produce more fines. During brewing, excessive fines can cause blockages, leading to extraction deviations and ultimately resulting in negative flavors like bitterness, thereby affecting the cleanliness of the entire cup of coffee. The simplest method is to use a sieve to remove the fines, but it's important to know that what causes negative flavors is "excessive fines," not "fines" themselves.

2. Roast Date

Coffee beans are not better the fresher they are. If we brew beans that have just been roasted, the resulting coffee will have an obvious dryness that makes people's throats feel uncomfortable, as if something is stuck in their throat. This is also a manifestation of insufficient coffee cleanliness.

Generally, freshly roasted coffee beans need a resting period of 4-7 days. This time is sufficient for the dryness to dissipate, resulting in a coffee with high cleanliness.

FrontStreet Coffee believes that cleanliness needs to be considered in conjunction with the entire cup's flavor and texture performance—it cannot be discussed in isolation. A good coffee possesses rich layers, full aroma, and appropriate aftertaste. As long as it meets these criteria, you can be confident that it has excellent cleanliness.

FrontStreet Coffee

No. 10, Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

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