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

Unlike usual hot water brewing, so-called cold brew mainly involves mixing cold water (room temperature water) with coffee grounds, letting it sit in a low-temperature environment for several hours, and finally filtering out the coffee grounds to get iced coffee liquid. A pack of coffee, a clean sealed container, and a refrigerator are all you need to enjoy cold brew freedom at home.

In fact, compared to the strict parameters of other coffee extraction methods, cold brew is highly compatible. From the choice of coffee beans to the sealed container used, to the coffee-to-water ratio, grind size, and steeping time, it has a wide range of adjustments. In other words, as long as the parameter combinations aren't particularly extreme, you can make a decent iced coffee.

Steeping 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 can change the taste of the coffee. Cold brew, however, only comes into contact with low-temperature water at 4-10°C throughout, so the extraction efficiency is very slow. Therefore, it's necessary to extend the steeping time to allow more aromatic substances to be released, thereby making the extraction of sugars and organic acids more complete, resulting in a coffee that is more balanced in acidity, sweetness, and body. Generally, the steeping time for cold brew coffee is recommended to be controlled between 8 and 18 hours.

Front Street Coffee once conducted a cold brew experiment using time as a variable, steeping a coffee for 6 hours, 10 hours, 16 hours, and 24 hours respectively. It was 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 showed 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 roast is often a primary consideration for many people. 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 gas allows us to intuitively judge whether the beans are fresh, such as the crema in espresso or the blooming during pre-infusion, 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 need to be released first. Cold brew itself is a relatively static extraction process, and low-temperature water to some extent inhibits the release of these gases, making the brewed coffee prone to becoming bland. Therefore, Front Street Coffee recommends using coffee beans with a roast date more than 10 days prior to making cold brew, which is more conducive to making a coffee with rich aroma.

Stir thoroughly before and after extraction

Many newcomers, aiming for speed, directly seal and put it in the refrigerator after adding water. The surface of the coffee grounds may look wet, but in reality, some parts haven't come into contact with water, so those dry parts of the coffee obviously haven't participated in the extraction. Additionally, after sitting overnight, most of the particulate matter sinks to the bottom of the container. If you pour it out directly for filtering at this point, there's a high chance you'll only get the lighter liquid on top, and the taste will presumably be poor.

Based on Front Street Coffee's experience, if you're using a larger capacity pot, before extraction, 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 again a few times before filtering. If you're using a sealed water bottle, after capping, just gently shake it up and down to mix.

Filter out the grounds thoroughly for a better cold brew taste

There are also many choices for equipment to filter coffee grounds, such as the built-in filter of a cold brew pot, metal filters, filter paper, and flannel cloth. The size of the filter pores naturally determines what particulate matter can be effectively blocked.

Taking Front Street Coffee's use of a cold brew pot as an example, the filter mesh size is 245 mesh, which is relatively fine, but there can still be fine and very fine particles passing through. If not filtered again, a layer of flocculent oil will float on the surface. The flavor of the coffee is not much different from after filtering, but the roughness left on the tongue when swallowing is relatively noticeable, and some visible grounds settle at the bottom of the cup after drinking.

For a better drinking experience, Front Street Coffee will use a denser filter paper to strain it once more, which not only effectively filters out the very fine coffee particles but also blocks more than 80% of the oils. After filtering out the grounds, Front Street Coffee will also put the cold brew coffee liquid into the refrigerator sealed and refrigerated for 3-4 hours, allowing the flavor substances to further settle and mature. This way, the cold brew tastes very full-flavored, with a clearer mouthfeel and more transparent acidity.

After the cold brew is made, should it be refrigerated again?

For the cold brew typically sold in stores, Front Street Coffee will put it into the refrigerator sealed and refrigerated for 3-4 hours after filtering out the grounds, before selling it.Although the refrigerator at home may look clean on the surface, there are actually many microorganisms invisible to the naked eye. If not careful, this can lead to food spoilage or deterioration. Therefore, to ensure the coffee is not contaminated by external factors, the container we use must be well-sealed and cleaned thoroughly. Refrigerating at low temperatures is not only to inhibit the reproduction rate of certain bacteria but also to allow the substances in the coffee to undergo a slow and controlled 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 allows water to soak the coffee grounds overnight, actually already has a relatively complete flavor. At this point, re-chilling the coffee liquid for several hours is more about allowing the dissolved substances to ferment further, bringing a clearer and more mellow coffee taste.

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

Front Street Coffee 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 problem that if not marked, it's 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 rate 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, the coffee liquid comes into contact with air, which not only causes the aroma to dissipate but may also introduce bacteria into the container. Generally speaking, for the sake of flavor experience and health safety, whether it's ice drip or cold brew, for any extraction method carried out in a low-temperature environment, Front Street Coffee recommends consuming it within 5 days (counting from the production date).