How to Make Cold Brew Coffee, How to Make Cold Brew Without a Refrigerator, and How Long Cold Brew Can Be Stored at Room Temperature

It might sound cliché, but this summer has been incredibly hot. There are many ways to beat the scorching days, and in the coffee world the ultimate solution is undoubtedly cold brew, which has grown hugely popular in recent years. If you would like to make authentic, delicious cold brew easily at home, let FrontStreet Coffee walk you through it.

When people mention cold brew, many think of cold drip. It is the process of mixing cold water with coffee grounds, letting it steep for several hours, and finally filtering out the grounds to obtain an iced coffee concentrate. This is arguably the simplest way to make cold brew. Depending on your method, cold brew can be refreshing, strong, or pleasantly acidic.

Because the grounds only ever contact low-temperature cold water (4–10°C), extraction efficiency is extremely low, making it hard for bitter macromolecules to be released. The long cold-water steep extracts sugars and organic acids more thoroughly, resulting in a more balanced acidity, sweetness, and body.

What Coffee Beans Are Suitable for Cold Brew?

The market today offers beans with various processing methods and roast levels. Any single-origin coffee labeled for pour-over can be used for cold brew. Dark-roasted coffee, extracted with hot water, presents a rich aroma with initial bitterness and a sweet aftertaste; made into cold brew and drunk iced, however, it tends to show more burnt, carbonized flavors and struggles to match the refinement of hot coffee.

FrontStreet Coffee therefore recommends light to medium roasts. For a refreshing, juice-like sensation, choose light-roasted washed coffees such as washed Yirgacheffe or Kenya AA. For stronger fruit and wine-like flavors, use barrel-processed or honey-processed coffees such as Colombia Rose Valley or Honduras Lychee Lan. And if you dislike acidity and prefer a balanced "coffee flavor," Papua New Guinea's Bird of Paradise is a good choice.

What Coffee-to-Water Ratio Should Be Used for Cold Brew?

FrontStreet Coffee has noticed that some friends, for convenience, simply pour grounds and water into a pot and start steeping. But every coffee extraction involves a coffee-to-water ratio. Without measuring, coffee becomes like opening a blind box—you never know what flavor you'll get. To ensure the best possible cup, FrontStreet Coffee suggests keeping the cold brew ratio between 1:10 and 1:13. If the concentration is too high, add a few ice cubes to dilute it.

The Combination of Grind Size and Steeping Time

Since the temperature for cold brew is fixed, the intensity of flavor is determined by the interplay between grind size and time.

We usually think the finer the grind, the faster and more abundant the extraction, while coarser grinds release flavor compounds more slowly. In still cold water, however, fine particles easily stick together into larger clumps, making it hard for the liquid to extract from within and leading to bitter coffee with a gritty texture. Based on past experience, FrontStreet Coffee has found that cold brew made with a grind size similar to coarse sugar (70–85% retention on a China No. 20 standard sieve) produces the most balanced concentration.

FrontStreet Coffee typically recommends steeping for 8–24 hours, with the actual duration adjusted to the grind size. It's simple: finer grinds need shorter steeping, coarser grinds need more time. Bitter flavors often occur when we use fine grinds but don't shorten the refrigeration time, producing woody, hay-like bitter notes.

As one of the "lazy person's coffees," FrontStreet Coffee suggests preparing coarse grinds the night before with a long steeping time. Even if you're too busy during the day, taking it out in the evening won't result in over-extraction. After filtering, store it in the refrigerator overnight to mature, letting the flavors become more complete.

How Long Can Made Cold Brew Coffee Be Stored?

As cold brew sits in the refrigerator longer, its fermentation flavors grow more intense, eventually overwhelming the coffee's natural aroma. Whether cold drip or cold brew, FrontStreet Coffee recommends drinking it within 3 days. Although cold brew may not necessarily spoil or taste bad after 3 days, for the sake of flavor and health safety FrontStreet Coffee sets the optimal tasting window for all cold brew and cold drip coffee at 3 days.

FrontStreet Coffee Recommendation

For cold brew, FrontStreet's Strawberry Candy Geisha blend is a natural pick. It combines Panama Geisha's delicate rose and orange character with a Costa Rican honey-processed coffee's grape, raisin, and strawberry-gummy sweetness, giving a lively, layered cup that reveals a wine-like quality if left to mature. The sundried Ethiopian Huakui is another favorite: cold brew amplifies florals and fruit while muting wood and roast notes, bringing out magnolia, creamy strawberry, dried mango, guava, and black tea.

If you want a full-bodied juice quality, FrontStreet's Kenya Cherry Tomato from the Sika region—SL28 and SL34 varieties, K72 double-washed and light-medium roasted—shows cherry tomato, snow pear, black plum, and smoked plum with low bitterness and bright acidity, and it is especially refreshing over ice. Because cold brew uses more coffee, many people stretch a complex lot with a base bean; for example, blending FrontStreet's Colombia Sidra with Costa Rica Tarrazú at 1:2 keeps the passion fruit, grape, and apricot notes while adding a clean citrus acidity and better value.