How Do Grind Size and Ratio Shape Cold Brew Coffee?

Cold brew is coffee extracted in cold water, not hot coffee chilled with ice. Grind the beans, soak them in cold water for at least 12 hours, then filter. Extend soaking to 24 or 48 hours for a heavier body. Using 50 grams of grounds as a baseline, the coffee-to-water ratio, grind size, temperature, and time all decide how the final concentrate tastes.

Because caffeine content varies with ratio and steep time, a strong batch of high test coffee can bring jitters, a racing pulse, or a lightheaded, buzzy feeling. That is caffeine at work, not alcohol, so can coffee make you feel drunk is a fair question but the answer is no. Store the concentrate in the fridge and dilute it before drinking.

On a scorching summer day, a glass of ice-cold, refreshing cold brew coffee becomes the top choice for many office workers. Compared with pour-over coffee, cold brew has a much lower barrier to entry—just grind and soak the coffee the night before, refrigerate overnight, and the next morning you can enjoy a rich, full-bodied iced coffee. However, to make a delicious cold brew, the coffee-to-water ratio, grind size, extraction temperature, and time are all indispensable parameters. Front Street Coffee, using 50 grams of coffee grounds as the baseline, has summarized a simple and easy-to-follow cold brew method, along with concentration adjustment suggestions for different drinking scenarios. This article will break down in detail the key points of making cold brew coffee, the reasons behind its flavor, and storage methods, helping coffee enthusiasts easily recreate a layered, sweet-aftertaste cold brew coffee at home.

As soon as summer arrives, all kinds of iced coffee make their way back into people's view. Drinking a glass of iced coffee in the sweltering heat instantly cools you down. Today, the star Front Street wants to talk about is none other than cold brew coffee from the iced coffee family. It is especially favored by office workers, and the reason is straightforward—it's just too convenient to make. Compared with pour-over coffee, which requires focused pouring technique, cold brew has almost no technical threshold.

Next, Front Street will explain cold brew coffee in detail.

As the name suggests, cold brew coffee is coffee extracted at low temperatures. Many people confuse it with iced coffee, but iced coffee usually refers to coffee first extracted with hot water and then cooled with ice when served. The most fundamental difference between the two lies in the extraction temperature. Cold brew coffee is made by grinding coffee beans, soaking them in cold water for at least 12 hours, and then filtering the extract with specialized equipment. If you want a more pronounced body, you can extend the soaking time to 24 to 48 hours.

Front Street thinks that although cold brew coffee takes a long time, the entire process requires no skill at all—a bottle, a bag of beans, one night, and the next morning you can drink a full-bodied, rich iced coffee. This is also an important reason why it is so popular. The principle of cold brew is not complicated: as long as you get the coffee-to-water ratio right and soak for more than 12 hours, you can get a refreshing, smooth cup of coffee. Grinding and brewing at home the night before, refrigerating overnight, and drinking cold coffee the next morning—that experience is truly wonderful.

Cold brew coffee and pour-over coffee have different extraction paths. Far fewer bitter compounds are extracted at low temperatures, and the method is also simple. Front Street believes that as long as the coffee-to-water ratio is right, anyone can make a delicious cold brew coffee.

Front Street's method for making cold brew coffee

As Front Street mentioned earlier, making cold brew coffee is very easy—even simpler and more straightforward than pour-over. As long as you choose the right parameters, you can easily make a delicious iced coffee. So, when making cold brew coffee, how should parameters like grind size and coffee-to-water ratio be determined?

Front Street generally recommends a coffee-to-water ratio of 1:12 for cold brew, that is, using 50 grams of coffee grounds as the baseline. The resulting cold brew concentration is just right—it can be drunk directly without dilution. Some friends like to add milk, soda water, or use it for specialty coffee drinks. In that case, a higher coffee concentration is needed. Front Street suggests adjusting the coffee-to-water ratio to 1:10 for cold brew used in specialty drinks.

Grind size for cold brew coffee

Grind size is closely related to the brewing method. Since cold brew coffee is extracted by soaking in ice water, the extraction efficiency is very low. In other words, there is basically no need to worry about over-extraction. When Front Street makes cold brew, the grind is slightly finer than for pour-over, with a reference of 85% passing through a No. 20 standard sieve, and the proportion of fines is kept as controlled as possible. However, Front Street also reminds everyone: although low-temperature extraction can reduce the release of bitter compounds, it is not 100%. If ground too fine, after the acidic and sweet substances in the coffee grounds are quickly extracted, the body-giving compounds will be released as well. An appropriate amount of body-giving compounds can enhance the coffee's body, but once the soaking time is too long, woody flavors will emerge, lowering the cleanliness of the entire cup.

Coffee-to-water ratio

Some friends may ask: exactly how much water should be used for soaking? Front Street's standard is a ratio of coffee, water, and ice of 1:8:4, which translates to an actual coffee-to-water ratio of 1:12. The purpose of adding ice is to ensure the water temperature is low enough to keep the extraction efficiency at a stable level.

Temperature

Front Street previously told everyone that the water temperature for pour-over coffee is related to the roast level, while cold brew coffee has no strict temperature requirements—just put it in the refrigerator for low-temperature extraction. Under low-temperature extraction, the soaking time needs to reach 24 hours. Can cold brew coffee be extracted at room temperature? Of course it can, but the time should be shortened accordingly. Front Street Coffee suggests compressing the time to 8 to 12 hours for room-temperature extraction.

Front Street Coffee's cold brew method uses 50 grams of coffee grounds as the baseline. After the coffee beans are ground, put them into a clean, oil-free sealed container, pour in 400 milliliters of room-temperature water, then add 200 grams of hard ice cubes (the ice-water mixture totals 600 grams), close the lid tightly and shake gently to let the coffee grounds fully contact the ice water, then place it in the refrigerator and let it sit for 12 to 24 hours. After extraction, filter out the coffee grounds with filter paper or a fine mesh, then pour the coffee liquid into a clean sealed bottle and refrigerate for about 4 hours before drinking.

How long can cold brew coffee be stored after filtering?

Front Street has talked about how to drink pour-over coffee—different temperatures bring different flavors—but pour-over should not be kept for long. Even if it is only kept for one day, it is best to finish it as soon as possible. Cold brew coffee is different. Theoretically, the longer cold brew sits, the stronger the fermented flavor becomes. But excessive fermentation will make the coffee lose its original flavor. For friends who do not really accept strong fermented flavors, Front Street does not recommend trying it lightly. The best drinking time for cold brew coffee is 2 to 3 days after filtering out the grounds, and the storage time is recommended not to exceed 7 days.

Low temperature and long extraction time are the two major characteristics of cold brew coffee, and also the main differences between it and hot-brewed coffee. Hot-brewed coffee uses hot water to extract coffee grounds, with a water temperature between 88 and 91°C, usually no more than 5 minutes. The fastest espresso takes only 18 to 23 seconds, while cold brew coffee far exceeds hot-brewed coffee in time. Speaking of the long extraction time of cold brew, Front Street uses a rather poetic phrase to describe it: "What you are drinking is not just a cup of coffee, but a long wait."

Characteristics of cold brew coffee

From a flavor perspective, high temperatures cause the tannic acid in coffee to break down into pyrogallic acid, bringing acidity and bitterness. Research shows that the acidic substances in cold brew coffee are 67% lower than in hot-brewed methods. Therefore, compared with hot-brewed coffee and iced coffee made by adding ice after hot brewing, coffee made by the cold brew process has lower acidity and astringency and is easier for the general public to accept. For friends who do not like acidic coffee, cold brew coffee is very suitable.

In addition, Front Street found that low temperatures plus long contact with coffee grounds allow only small-molecule flavor substances to be extracted, such as floral and fruity aromas; while larger-molecule flavor substances, such as smoky and roasted notes, are difficult to extract. This also explains why cold brew coffee does not have a very sensory-arousing aroma when smelled, but tastes smoother, richer, more layered, with obvious sweet aftertaste and no greasy feeling.

Of course, all of this is premised on the coffee beans being fresh enough. Front Street Coffee deeply understands that the freshness of coffee beans greatly affects flavor. Front Street's roasting philosophy is "freshly roasted good coffee," so that every customer who places an order receives the coffee in its freshest state. Therefore, the coffee beans shipped by Front Street Coffee are all within 5 days of roasting. The resting period for coffee is about 4 to 7 days, so when customers receive it, it is at its best flavor.

Front Street believes that any coffee-making method requires constant practice, so that all the flavors of coffee can be better presented. Front Street has fifty different coffees from different origins, allowing everyone to better taste different coffee flavors; friends can also come to Front Street Coffee to discuss coffee with our baristas!

The above content is compiled by CoffeeHunters, a coffee news website.