Some of you might think, isn't cold brew coffee just coffee grounds soaked in cold water for a long time? Actually, that's not the case! A delicious cold brew coffee involves more than just these parts; it also requires attention to some small details to assist our extraction. But as long as we get it right, we only need to take a few steps to easily make a tasty iced coffee. Here, Front Street has summarized several important details about the steps for making cold brew coffee. Those at home might want to check themselves against these, which can help us make a standard cold brew coffee that is icy and rich.

Unlike regular hot water brewing, so-called cold brew mainly uses cold water (room temperature water) mixed with coffee grounds, left to stand in a low-temperature environment for several hours, and finally filtered to remove the coffee grounds to get iced coffee liquid. A pack of coffee, a sealed clean container, and a refrigerator are all you need to achieve cold brew freedom at home.

In fact, compared to the strict parameters of other coffee extraction methods, cold brew is highly compatible, with a wide range of adjustments from coffee bean selection to the sealed container used, and to the powder-to-water ratio, grind size, and soaking time. In other words, as long as the parameter combinations are not particularly extreme, you can make a good iced coffee.

The soaking time should not be less than 8 hours or more than 18 hours.

In pour-over, we pay special attention to water temperature and time because water, as the main medium for brewing, directly affects the extraction efficiency of coffee; too high or too low will change the taste of the coffee. However, cold brew, as it only contacts low-temperature water at 4-10°C throughout, has a very slow extraction efficiency, so it requires extending a certain soaking time to allow more aromatic substances to be released, thereby enabling more complete extraction of compounds such as sugars and organic acids, resulting in a coffee that is more balanced in acidity, sweetness, and body. Generally, the soaking time for cold brew coffee is recommended to be controlled between 8 and 18 hours.

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

Too fresh coffee beans can also affect extraction.

In many high-temperature brewing methods, freshness of roasting is often the first factor many people consider. Firstly, beans not in their optimal flavor period will have a greatly reduced aroma, which is a consensus everyone has reached; secondly, the release of gases allows us to intuitively judge whether the beans are fresh, such as the crema in espresso or the bubbling during blooming, which also indicates that the coffee is at its peak aroma stage.

As coffee beans are continuously heated in the roaster, freshly roasted beans contain a large amount of carbon dioxide. To extract the aromatic compounds inside, these gases must be released first. Cold brew itself is a relatively static extraction state, and low-temperature water to some extent inhibits the release of these gases, so the brewed coffee can easily become bland. Therefore, Front Street recommends using coffee beans with a roast date more than 10 days old to make cold brew, which is more conducive to making a coffee with rich aroma.

Stir thoroughly before and after extraction.

Many newcomers, in their haste, directly cover and put it in the refrigerator after adding water. The surface of the coffee grounds may look wet, but in fact, some parts have not come into contact with water, so the dry portion of the coffee clearly has not participated in the extraction. Additionally, after standing overnight, most of the particulate matter sinks to the bottom of the container. If you pour it out and filter directly at this point, there is a high chance you will only get the lighter-colored liquid on top, and the taste will presumably not be good.

Based on Front Street's experience, if you are using a larger-capacity pot, you can use a stirring rod or a long spoon to mix the coffee grounds and water evenly before putting it in the refrigerator. After taking it out, stir it a few more times before filtering. If you are using a sealed water bottle, after capping, simply shake it gently up and down to mix.

Filter out the grounds thoroughly for a better cold brew taste.

There are also many choices for filtering coffee grounds, such as the built-in filter of a cold brew pot, metal filters, filter paper, and flannel filter cloth. The different sizes of the filter pore structure naturally determine the particle matter they can effectively block.

Taking Front Street's use of a cold brew pot as an example, the filter mesh size is 245 mesh, which is a relatively high fineness type, but there is still the situation of fine powder and ultra-fine powder passing through. If not filtered again, a layer of flocculent oil slick will float on the liquid surface. The flavor when drinking the coffee is not much different from after filtering, but the rough sensation left on the tongue when swallowing is relatively obvious, and after drinking, some visible powder residue settles at the bottom of the cup.

For a better drinking experience, Front Street uses a higher-density filter paper to strain it again, which can not only effectively filter out the ultra-fine coffee powder but also block more than 80% of the oils. After separating the grounds, Front Street will also put the cold brew coffee liquid into the refrigerator, sealed and refrigerated for 3-4 hours, to allow the flavor substances to further settle and mature. In this way, the cold brew tastes very full in flavor, with a clearer mouthfeel and more transparent acidity.

After the cold brew is made, should it be put back in the refrigerator for cold storage?

For the cold brew usually served in stores, Front Street puts it into the refrigerator, sealed and refrigerated for 3-4 hours after straining the grounds, before selling it.Although the refrigerator at home may look clean on the surface, in reality, there are many microorganisms that are hard to detect with the naked eye. If not careful, this can easily lead to food spoilage or deterioration. Therefore, to ensure the coffee is not contaminated by the outside, the container we use must have good sealing performance and be cleaned thoroughly. Low-temperature storage is not only to inhibit the reproduction rate of certain bacterial colonies but also to allow the substances in the coffee to undergo a slow and controllable fermentation process. This also explains why the longer ice drip is stored, the stronger the fermented flavor of the coffee becomes.

Compared to ice drip extracted at room temperature, cold brew, which soaks the coffee grounds in water overnight, actually already has a relatively complete flavor. At this point, re-chilling the coffee liquid for several hours is more about allowing the water-soluble substances to further ferment, bringing a clearer and mellower coffee taste.

How many days can cold brew stored in the refrigerator last at most?

Front Street has noticed that many convenience-seeking friends will soak a large pot of coffee at once and store it in the refrigerator, pouring it out whenever they want to drink. This also leads to the situation where, if not marked, it is easy to forget how many days the coffee has been in the refrigerator and whether it might have spoiled.

Firstly, the fermentation process of low-temperature extraction is uninterrupted; refrigeration only slows down the fermentation speed of the coffee. As time passes, the substances dissolved in the water continuously change, eventually leading to spoilage. Additionally, each time we open the bottle cap, it actually causes the coffee liquid to come into contact with air, which not only leads to the dissipation of aroma but may also bring bacteria into the container. Generally speaking, for the sake of flavor experience and health safety, whether it is ice drip or cold brew, as long as it is a low-temperature extraction method, Front Street recommends everyone drink it within 5 days (counting from the production date).

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