Cold brew coffee essentially refers to the fact that under low-temperature conditions, small-molecule substances tending toward aroma and acidity are more easily released into cold water, so the coffee tastes light and usually presents a sweet-and-sour profile. In addition, because it is not limited by equipment or location, cold brew can be said to be coffee that people can easily get their hands on. At home, as long as you have ingredients, a bottle, water, and a refrigerator, you can easily achieve caffeine freedom.

At this point, some observant friends have noticed a phenomenon: unlike pour-over coffee, which is almost "unchanging at 1:15," the coffee-to-water ratio for making cold brew always varies widely. Some people like to use 1:8, others advocate 1:13, and some, like Front Street Coffee, are used to producing it at 1:10. So what kind of taste experience will cold brews made with different ratios have?

What effects does the coffee-to-water ratio have on coffee?

As a typical immersion extraction, cold brew coffee is the process of extracting flavor by keeping low-temperature water and coffee grounds in the same container in contact for a long time. When other parameters remain unchanged, the larger the proportion of water, the lower the concentration of the coffee liquid, the weaker the coffee flavor, and the thinner the mouthfeel; conversely, the smaller the proportion of water, the higher the concentration, the stronger the taste, and the thicker the mouthfeel.

Therefore, in order to find a balanced taste and allow the coffee to present a better flavor, we must apply an appropriate coffee-to-water ratio.

How long should cold brew be steeped? How fine should the coffee grounds be ground?

We all know that the various parameters involved in any extraction plan are more or less related. For cold brew, the coffee-to-water ratio is not what determines the tasteonlyfactor; we also need to look at grind size, steeping time, water quality, and most crucially, the coffee beans.

Although low-temperature extraction can reduce the emergence of bitter substances, it is not 100 percent effective, so if you want to pursue deliciousness,the coffee grounds used for cold brew should not be ground too fine, and even more so should not be steeped too long. For the former, we recommend controlling the pass-through rate on a 0.85 mm standard sieve at about 80-85%, so that it looks like granulated white sugar to the naked eye; for the latter, it is best to keep it within 6-16 hours, because in this wayit ensures sufficient contact time between grounds and water, and at the same time alsomakes it less likely to show negative flavors due to over-extraction.

The reason Front Street Coffee emphasizes water quality is not only because it is the medium of extraction, but also because among all parameters it is the easiest for people to overlook. For example, in Front Street's back end, there are always friends asking why, even though they bought our coffee beans and followed the parameters provided in the article to make cold brew, the taste is just not as good as expected. After eliminating various "culprits," it turned out that the problem came from that colorless and tasteless "water." Friends with similar troubles can refer to Front Street's past comparison experiment "The difference in cold brew made with different waters is actually this big!", and we will not elaborate too much here.

Regarding the choice of coffee beans, here Front Street uses Kenya AA from the bean shelf as an experimental demonstration. It uses the K72 washed processing method, and the varieties are SL28 and SL34. Both SL28 and SL34 are varieties selected after multiple cultivations. SL28 belongs to the Bourbon genetic group and carries the bright tonality and rich acidity of the original Bourbon, while SL34's lineage is closer to the Typica gene, with a gentler acidity.

Iced coffee made from Kenya AA has an entry impression of dark berries wrapping around the mouth, along with a full small-tomato aroma. When drunk iced, it is very satisfying, so it is the first choice bean for many friends when making cold brew.

How does cold brew coffee made with different coffee-to-water ratios taste?

Because cold brew is always carried out in an environment of 0-10°C, the extraction efficiency is very low. In addition, the coffee grounds and water are in a relatively static state, and there is no external force driving them in the middle, so the speed at which the coffee grounds dissolve flavor substances is very limited. In order to make the experimental results clearer, Front Street set up 4 relatively common coffee-to-water ratios here, namely 1:8, 1:10, 1:12, and 1:15, with all other parameters kept unchanged.

The production process was completely the same. Pour the coffee grounds and water into the container in sequence, then stir and seal, and then place them in the refrigerator one by one. When the time is up, we take them out and filter them (they can be stirred once midway).

Coffee beans: Kenya washed AA

Coffee dose: 18g

Steeping time: 6 hours

Grind size: granulated sugar / 80% pass-through rate on China No. 20 standard sieve (EK43s setting 9.5)

Coffee-to-water ratio: 1:8, 1:10, 1:12, 1:15

Corresponding water amounts: 144g, 180g, 216g, 270g

The coffee liquid with a coffee-to-water ratio of 1:8 had the darkest color, the strongest taste, and was also the most sour,mouthfeeleven a little salty, with only a little berry in the flavor and a bitter finish;

the coffee liquid with a coffee-to-water ratio of 1:10 smelled of fresh sugarcane, with flavors of red plum, berries, and snow pear tea, a mouthfeel slightly on the strong side, high acidity, and no obvious sweetness;

the cold brew with a coffee-to-water ratio of 1:12 had the clearest mouthfeel, with flavors of small tomato, red plum, smoked plum juice, sugarcane, and the lingering fragrance of preserved plum candy, with moderate concentration,balanced sweetness, acidity, and bitterness;

the coffee liquid with a coffee-to-water ratio of 1:15 had the lightest color, a relatively thin body, and only a little acidity from black plum and berries,with a plain taste, but almost no bitterness.

From the above comparison, it is not difficult to see that because the 1:8 ratio uses less water, the coffee flavor does not have enough room to develop and is also prone to showing the negative characteristic of being thick and bitter; on the other hand, because the 1:15 ratio uses more water, the soluble substances are overly diluted, resulting in insufficient body and purity, so it naturally tastes bland and flavorless.

Among the two groups of 1:10 and 1:12, the cold brew coffee made with 1:12 clearly showed the best flavor and mouthfeel when drunk directly, butFront Street gives priority to 1:10 in many articles and daily production. Why is that?

For the production of cold brew, Front Street mainly considers two points.

First, in order to keep the cold brew at a low-temperature mouthfeel, in addition to using iced cups to hold it, we also add 1-2 hard ice cubes, so that even if the coffee is diluted, the flavor will not be changed too much; second, because every guest has different taste preferences, some like it light and some like it strong, when the ice cubes are just added, the coffee has a full and thick mouthfeel, and as they slowly melt into water over time, the coffee gradually becomes lighter. Therefore, using a high-concentration version of cold brew with ice satisfies both the "heavy-flavor camp" and the "light-flavor camp."

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