Besides hot water extraction, coffee can also be made with cold water. Coffee made with cold water is called "cold brew coffee," and it has a distinctive character compared to hot-brewed coffee.

Cold brew coffee is divided into cold steep coffee and ice drip coffee. Cold steep coffee is made by soaking coffee grounds in cold water, while ice drip coffee refers to extracting coffee drop by drop using a drip filtration method. Some friends asked Front Street: "Is it better to soak cold steep coffee with hot water or cold water?" Coffee soaked with hot water cannot be called cold steep coffee. Cold steep coffee can only be soaked with room-temperature water or ice water, and the soaking environment must be kept at a low temperature.

Since it only contacts low-temperature cold water at 4-10°C throughout the process, the extraction efficiency is very low, and bitter macromolecules are not easily released. Long low-temperature soaking allows compounds such as sugars and organic acids to be extracted more fully, so the acidity, sweetness, and body of the coffee are more balanced.

So how should cold steep coffee be made to taste good? Here Front Street shares a few operational details with everyone.

Selection of coffee beans

If you don't want to fail, Front Street recommends choosing medium-light roasted coffee beans, which have a higher tolerance for error compared to medium-dark roasts. Currently, there is a dazzling variety of processing methods and roast levels on the market, but as long as they are single-origin coffee beans labeled for pour-over use, they can all be used to make cold brew coffee. Dark-roasted coffee, when extracted with hot water, presents a rich coffee aroma, first mellow and bitter then sweet; but when made into cold brew, drinking it at ice-cold temperature tastes more scorched-bitter and carbonized, and it is hard to achieve the refinement of hot coffee.

Therefore, Front Street more strongly recommends light to medium roasted coffee beans. If you want a refreshing juicy feel, you can choose light-roasted washed coffee, such as washed Yirgacheffe or Kenya AA. If you want a stronger fruity and vinous aroma, you can use barrel-aged or honey-processed coffee, such as Colombia Rose Valley or Honduras Lychee Orchid. If you don't like coffee with acidity and only like a balanced "coffee taste," you can also choose Papua New Guinea Bird of Paradise.

Coffee grind size

Since cold brew is made in a low-temperature environment, cold water extracts coffee grounds relatively slowly, and compared with hot water extraction, bitter substances are not easily released. Therefore, in terms of grind size, coffee-to-water ratio, and soaking time, it is not as strict as pour-over coffee. Usually, as long as it roughly falls within a range, and the coffee beans are chosen correctly, a delicious iced coffee can be made in a few simple steps.

Taking Front Street's daily cold brew production as an example, the coffee beans are ground slightly finer than for pour-over, that is, a passing rate of 75-80% through the Chinese No. 20 standard sieve. To the naked eye, it is about the degree of fine granulated sugar, corresponding to a setting of 9.5-10 on the EK43s. For a hand grinder, using the C40 as an example, it is about 22-26 clicks.

Soaking time

In pour-over, we pay special attention to water temperature and time, because water, as the main brewing medium, directly affects the extraction efficiency of coffee, and too high or too low will change the taste of the coffee. Since cold brew only contacts low-temperature water at 4-10°C throughout the process, the extraction efficiency is very slow, so a certain soaking time needs to be extended to release more aromatic substances, thereby allowing compounds such as sugars and organic acids to be extracted more fully, and the resulting coffee is more balanced in acidity, sweetness, and body. Generally, the soaking time for cold brew coffee is usually recommended to be controlled at 8-18 hours.

Front Street once conducted a cold brew experiment with time as the variable, soaking one coffee for 6 hours, 10 hours, 16 hours, and 24 hours respectively. In the end, it was found that the 6-hour coffee had too thin a mouthfeel and flat aroma, while the cold brew soaked for 24 hours was noticeably bitter and showed signs of over-extraction. The 10-hour and 16-hour groups had the best flavor performance, with rich aroma and a full-bodied mouthfeel.

Coffee-to-water ratio

Front Street has noticed that some friends, for convenience, directly pour coffee grounds and water into a pot and start soaking. As long as it is coffee extraction, the parameter of coffee-to-water ratio is involved. Without weighing, coffee is like opening a blind box; you never know what taste you will get. To ensure the brewed coffee tastes better, Front Street recommends controlling cold brew production at 1:10-1:13. If the concentration is too high, an appropriate amount of ice cubes can be added to dilute it.

Finally, Front Street will talk about Front Street's cold brew coffee making method! First, for coffee beans, Front Street tends to use medium-light roasted coffee beans. For the container, only a clean sealable container is needed. Prepare 40 grams of coffee grounds, grind to a fine grind (85% passing rate through a No. 20 sieve), pour into the container, then pour in 480 milliliters of cold water, stir evenly with a wooden stick, and cover with a lid.

After stirring evenly, seal the mouth with plastic wrap, place in the refrigerator and refrigerate for 12 hours, then remove and filter out the grounds. After filtering out the coffee grounds, the clear coffee liquid can be drunk immediately, or the filtered coffee liquid can be put into a bottle and continue to be refrigerated for 4 hours, and the flavor and mouthfeel will be even better.

Generally speaking, for considerations of flavor experience and health safety, whether it is ice drip or cold brew, as long as it is an extraction method carried out in a low-temperature environment, Front Street recommends everyone drink it within 5 days (counting from the production day).

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