How Long Should Cold Brew Coffee Steep? A Guide to Grind Size and Water-to-Coffee Ratio

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FrontStreet Coffee believes that cold brew coffee is the most suitable type of iced coffee for home preparation because its extraction compatibility is very high. Even without professional equipment, you can make excellent iced coffee. Additionally, since some friends recently asked FrontStreet Coffee about grind size and steeping time, today is the perfect opportunity to discuss this topic.

Although this friend didn't ask about ratios, various parameters in any extraction method have corresponding relationships, so FrontStreet Coffee still needs to mention the ratio. FrontStreet Coffee recommends using a coffee-to-water ratio between 1:12 to 1:13 for making cold brew coffee. In FrontStreet Coffee's experiments, ratios above 1:13 resulted in some coffee beans tasting rather weak and flat. Ratios below 1:12 would appear somewhat concentrated and difficult to swallow.

Grind Size and Time Selection for Cold Brew

Next, FrontStreet Coffee will explain how to choose the grind size and time for cold brew coffee. At this point, we need to discuss the extraction principle of cold brew coffee. Cold brew coffee essentially belongs to the immersion category, meaning we can control the time parameter ourselves (steep for as long as desired, end whenever we want).

However, cold brew has another characteristic: low-temperature extraction. This means the extraction temperature is a set constant. Whether we want our cold brew coffee to be bright and crisp or rich and full-bodied depends on the two parameters of grind size and time. Compared to other extraction methods with multiple variables, cold brew coffee is the simplest and most user-friendly extraction method.

Understanding Grind Size

In terms of grind coarseness, it's easy to understand that the finer the coffee is ground, the faster the flavor develops (coffee substances release more quickly), while the coarser the grind, the slower the coffee powder releases substances. However, FrontStreet Coffee wants to remind you that because cold brew coffee involves long-term static extraction, if the coffee is ground too fine, these coffee particles will "clump" and stick together, making it harder for cold water to extract coffee substances.

Therefore, coffee grounds that are too fine are not suitable for making cold brew coffee. After multiple experiments, FrontStreet Coffee has found that a coarseness similar to pour-over coffee (if using a #20 sieve screen, with a pass rate between 70-85%) can be used to make cold brew coffee.

Understanding Steeping Time

Time is even easier to understand - the longer you steep, the more total substances are released from the coffee, making the coffee stronger. However, more dissolved substances don't necessarily mean better coffee. Through experiments, FrontStreet Coffee has learned that when steeping time exceeds 24 hours, cold brew coffee easily develops bitter flavors reminiscent of nuts and wood chips. Meanwhile, steeping for less than 8 hours results in insufficient substance release, likely producing coffee-flavored water. Therefore, the safer steeping time for cold brew coffee is 8-24 hours.

Why the Wide Time Range?

At this point, some friends might ask: why can this time range be so wide, 8-24 hours, with a difference of 16 hours? Wouldn't the flavor difference be significant? When extracting espresso, a difference of 1 second might result in significant flavor variation. When making pour-over coffee, a difference of 20 seconds can distinguish flavor changes. This is because espresso uses high-temperature, high-pressure extraction, and pour-over also uses high temperature plus stirring force to improve extraction efficiency. In contrast, cold brew coffee's water temperature averages 4-10 degrees Celsius, with very low extraction efficiency. Additionally, since the coffee grounds and water are in a relatively static state without external force driving them, the flavor substances released from the coffee grounds are very limited.

When steeped for 8 hours, the coffee's flavor will have bright acidity and a refreshing sensation.

When steeped for 16 hours, the coffee's flavor will be relatively round and full, with ample sweet and sour notes.

When steeped for 24 hours, the coffee's flavor and texture will be relatively thick, rich, and balanced.

Recommended Cold Brew Extraction Methods

If we divide the grind size range (70-85% pass rate on #20 sieve screen) into three levels: coarse, medium, and fine. And divide the time range (8-24 hours) into short, medium, and long. Then reasonable cold brew coffee extraction methods would be:

The safe approach is coarse grinding with long extraction time - this is perfect for lazy people. For example, if you have free time today, you'll likely have free time at the same time tomorrow, which saves calculation time (and prevents forgetting that you're steeping cold brew).

The time-saving approach is medium-fine grinding with medium to long time. This method can shorten the time accordingly, and reduced extraction time will also make the coffee taste relatively refreshing.

FrontStreet Coffee's Cold Brew Recipe

Finally, FrontStreet Coffee will share FrontStreet Coffee's cold brew making method!

First, regarding coffee beans, FrontStreet Coffee tends to use light to medium roast coffee beans. Here, we're using FrontStreet Coffee's Strawberry Candy beans, which have a full-bodied juice-like quality. For the container, any clean, sealable container will suffice. Prepare 40 grams of coffee powder, ground to a fine grind (85% pass rate on #20 sieve screen), pour it into the container, then add 480 milliliters of cold water, stir thoroughly with a wooden stick, and cover with a lid.

Place in the refrigerator to cold steep for 12 hours. Then remove and filter out the grounds. The coffee liquid after filtering out the grounds can be consumed immediately, or you can bottle the filtered coffee liquid and continue refrigerating for 4 hours for even better flavor and texture.

The Strawberry Candy cold brew made this way has balanced sweet and sour notes, with soft berry and rose aromatics. Orange-like sensations fill the mouth, accompanied by round, sweet notes of almond and preserved fruit after swallowing.

Important Notice :

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