The reason why many people choose cold brew coffee is not only because of its temperature, but also because of its smooth and full coffee taste and its ability to better showcase the unique aroma and taste of a coffee bean.
In terms of flavor, high temperature will decompose the tannins in coffee, causing sourness and bitterness. Studies have shown that cold-brewed coffee contains 67% less acid than hot-brewed coffee. Cold brew coffee has less acidity and is generally popular among people.
Low-temperature conditions and long-term contact with coffee powder cause only small-molecule flavor substances, such as floral and fruity aromas, to be released into the water, while those with larger molecules, such as smoked flavor, roasted flavor, etc., are difficult to extract. This is why cold brew coffee doesn’t smell as strong, but tastes smoother. Made from the same coffee beans, although the flavor of cold brew is not as rich as hot brew, the taste is fuller and cleaner than other iced coffees.
Different from high-temperature/hot-water extraction coffee, cold-brew coffee is a cold-drink coffee that uses cold or room temperature water to soak coffee powder, refrigerate it in the refrigerator, and extract it for many hours. Regarding its production, Front Street has shared many useful articles. You can go directly to "Complete knowledge about Qian Street Coffee” Flip through it. Although a lot of the content is very detailed, some friends still occasionally encounter problems in actual operation. Among them, the feedback of "cold brew is too bitter" and "cold brew is too sour" are the most common cases. Today we will briefly analyze the reasons behind them.
If Pour over(V60) coffee is the face of hot coffee, then cold-brewed coffee is the representative of low-temperature extraction. Since cold brewing is always at a low temperature and is not subject to external intervention during the soaking process, the two parameters of water temperature and technique can be excluded in theory, and are more affected by other aspects.
Cold brew coffee is too bitter
When we feel a cup of coffee is too bitter, it’s either because of personal taste or because too much of the bitter substances were dissolved during extraction.
1. The coffee beans are roasted too darkly
On weekdays, many people will ask Front Street, which coffee beans are suitable for cold brew? In fact, all coffee beans are acceptable. Whether they are Pour over(V60) single products, Italian blends, dark roasts or light roasts, they can all be soaked in cold water. However, they will show different tastes in low temperature environments.
The darker the roasting degree, the less sour, and the bitter substances caused by the caramelization reaction will increase, making the cold brew more likely to be bitter. So if you can't tolerate bitter coffee, be sure to exclude those shiny Italian beans first. For single products, it is recommended to choose light to medium roasted beans, such as Front Street Bird of Paradise with a balance of sourness and bitterness and nutty aroma, refreshing and pleasant red cherries, and Front Street Strawberry Candy with rich fruity aroma and sweet aftertaste.
2. The grinding degree is too fine
When soaked in cold water, the extraction efficiency of coffee is very slow, so don't worry too much about over-extraction. The grinding degree for cold brewing in Front Street is usually finer than that for hand brewing (0.5 to 2 grids, as shown below), which is about the thickness of the No. 20 screen with a passing rate of 82%. It corresponds to the 9.5 grid scale of the electric grinder EK43s, and the scale of the hand grinder C40 is 22 to 24 grids.
However, Front Street reminds everyone that although low-temperature extraction can reduce the appearance of bitter substances, it is not 100%. If the grind is too fine, the sweet and sour substances in the coffee powder will be quickly extracted, and the mellow substances will be released. An appropriate amount of macromolecules can increase the body of coffee, but if soaked for a long time, a woody taste will begin to appear, reducing the overall cleanliness of the coffee.
(grinding too finely)
3. Soaking time is too long
Many novices think that cold brew coffee tastes better the longer it is brewed, but this is not the case. The more coffee substances are dissolved, the better. When the content extracted by water exceeds a certain threshold, the good taste will turn into a negative effect, making the coffee taste like wood, bitterness, straw, etc.
Front Street once conducted a comparative experiment, using the same coffee beans for 4 hours, 10 hours, 16 hours, and 22 hours respectively, and making a pot of cold brew with the same parameters. Finally, it was found that the coffee soaked for 22 hours showed signs of slight over-extraction, which was caused by too much release of substances in the tail section. Combined with Front Street’s years of production experience, cold brew coffee is the most reliable when soaked for 8 to 18 hours.
4. The filter is not clean
Cold brew production actually has very low requirements for soaking containers and filtering equipment. It can be the built-in filter that comes with the cold brew pot, or you can use the tea filter, filter cloth, filter paper that is readily available at home, or the metal filter in the French press. Although they all have sieving functions, the finenessalwaysIt is far inferior to filter paper. If it is not filtered again, the coffee will taste very rough and easy to have a bitter aftertaste. There may even be some powdery residue visible to the naked eye at the bottom of the cup after drinking.
For a better drinking experience, Front Street uses filter paper to sift every time. The moderately thick filter paper can not only effectively filter fine powder, but also block more than 80% of grease, making the ice coffee taste cleaner.
Cold brew coffee is too sour
1. Coffee beans are lightly roasted
Like bitterness, everyone's tolerance for sour coffee is different. The lighter the roasting degree, not only retains more acidic substances, but also "suppresses" the sweetness brought by the caramelized substances due to the short heating time. In addition, in the low-temperature extraction environment, small molecules are released preferentially, so that the coffee shows the characteristics of low body, high acidity, and thin aroma during cold extraction.
If you are looking for iced coffee that is fruity but not sour, you can give priority to coffee from South America, especially beans whose flavor descriptions include words such as tropical fruits, preserved fruits, and fermentation, such as Front Street Blackberry, Front Street Cicada, and Front Street Big Belly Button. Because they have a caramel flavor, over time, this aroma will brew into a cup of iced coffee with a full taste and aroma.
2. Lack of fermentation time
Although it has been soaked for a long time, it is cold water extraction after all. After filtering, there are many suspended substances that are not completely dissolved into the water. If you happen to use lightly roasted beans, the sourness is likely to dominate, and it lacks body and roundness.
In this regard, Front Street recommends sealing the filtered cold brew and placing it in the refrigerator for 3 to 5 hours to allow the flavor substances released in the previous step to fully react with the water, thus promoting the "maturation" of the coffee.
