What Does Coffee Cleanliness Mean? Which Coffee Beans Have Better Cleanliness?

When it comes to first impressions of coffee, distinctive flavors often attract the most attention. However, the cleanliness of a cup of coffee is equally important.

What Does Clean Coffee Mean?

According to FrontStreet Coffee, a clean coffee is one without any off-flavors or defect notes—it should be clear and pure. Off-flavors and defect notes generally refer to tastes that are universally considered undesirable. Imagine you wouldn't want to taste earthy, woody, or rubbery flavors in your coffee.

Clarity and purity, of course, mean that the coffee you drink is comfortable and allows you to clearly perceive its flavors from the first sip. Some coffees may not exhibit defect flavors, but their flavors are vague and difficult to distinguish, giving a cloudy sensation, which also indicates a lack of cleanliness.

Is Cleanliness Related to Concentration?

There seems to be a concept circulating that lighter coffee generally exhibits good cleanliness. This might be true, but it's not entirely correct.

As mentioned earlier, clean coffee has no defects or off-flavors—it's clear and pure. From a cupping perspective, this tests the quality of coffee beans, meaning whether the beans have been compromised by external contamination or human error during cultivation, harvesting, processing, or roasting.

Of course, the coffee beans you purchase have undergone层层 screening by bean selectors and roasters, so they are generally of first-tier quality. Therefore, we should focus our attention on the final step—brewing.

① Beans that are too fresh tend to have a roasted flavor, which can affect the cleanliness of a cup of coffee. Similarly, coffee beans that are no longer fresh will also impact cleanliness.

② A common cause of cloudiness in brewed coffee is excessive agitation during water pouring, or uneven grinding that creates too many fine particles, leading to localized over-extraction and bitterness.

Often, making coffee lighter in concentration can make it appear cleaner. This is because the coffee's concentration is lower—meaning there are fewer soluble substances per unit volume, so some negative flavor compounds are relatively reduced. This can "deceive" our senses, masking these negative flavors and creating a very clean sensation. However, this also makes the flavors weaker, giving a watery feeling, which won't provide you with a pleasant coffee experience.

How Can You Brew Clean Coffee?

① Bean Resting

As mentioned earlier, overly fresh coffee beans can have a "roasted" flavor—this is the smoky taste remaining inside the beans after high-temperature roasting. It needs time to mature and release carbon dioxide to dissipate. Therefore, letting the beans rest for a few days during the resting period will reveal cleaner taste and more prominent flavors.

② Bean Sorting

Sorting beans before brewing is still necessary. Although they've undergone multiple screenings during green bean processing and roasting, some slightly defective coffee beans may be overlooked. Removing these defective beans will reduce the risk of off-flavors. As for how to sort them, follow your intuition—just pick out any that don't look right.

③ Avoid Over-Extraction

Over-extracted coffee will become cloudy relatively quickly because undesirable compounds have been extracted out, making bitterness and off-flavors inevitable. High water temperature, fine coffee grinding, excessive agitation during water pouring, and other factors can all lead to over-extraction.

Important Notice :

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