What makes a good cold brew coffee? There is no detailed standard, everyone has their own methods and standards. What details should be paid attention to when making cold brew coffee, the choice of coffee beans, grind size, coffee-to-water ratio, drip speed, storage and shelf life, etc. This article will cover various operational details.
1. Coffee beans for making cold brew
Cold brew and ice drip both belong to low-temperature extraction coffee brewing methods. The temperature at which water contacts coffee grounds is controlled between 0-7°C. The advantage of low-temperature extraction is that by utilizing the principle of low extraction efficiency at low temperatures, it can reduce the release of large-molecule bitter substances, so the cold brew coffee we drink will be refreshing, with rich sweet and sour flavors.
Since ice drip cannot extract a large amount of aromatic substances from coffee grounds with high-temperature water, especially the large-molecule aromatic compounds that medium-dark roasts focus on are difficult to dissolve in ice water, it is usually made with light to medium roast coffee beans that have obvious floral and fruity aromas, sweet and sour notes, or fermented aromas.
Among them, single-origin coffee beans with unique flavors are recommended first. If you like highly sweet iced coffee, you can use beans rich in ripe fruit flavors such as Front Street Xizhua, Front Street Strawberry Candy, and Front Street Elto; but if you prefer sour coffee, you might start with Front Street Little Tomato, Front Street Fruit Ding Ding, and Front Street Huakui. Of course, Front Street sometimes also blends two coffee beans together, hoping to create a more complex-tasting cold brew coffee. For example, today's recipe is 20 grams of Front Street Strawberry Candy + 40 grams of Front Street Red Cherry. The resulting iced coffee has candied fruit, sweet orange, and rose floral aromas, and after drinking it also presents a fresh lingering charm like lemon and berries.
Front Street suggests that the coffee beans used for making ice drip are best chosen around 20 days after the roast date, because freshly roasted coffee beans release a large amount of carbon dioxide gas. When ice water drips into the ground coffee, gas is continuously released, and the coffee bed easily expands and bulges, eventually forming channeling effects, resulting in uneven extraction and greatly reducing the taste of the coffee.
2. The importance of leveling the coffee grounds
Ice drip coffee must be tamped. Many people do not understand why ice drip coffee also needs tamping.
Here, it should be noted that tamping ice drip coffee does not mean tamping it firmly, but first gently tapping the grounds to keep the structure of the coffee grounds in the filter cylinder uniform, and then using a flat-bottom tamper to gently level it. Remember to press gently and level it when tamping, not press it firmly like when extracting espresso. If the grounds are pressed too firmly when tamping, since ice drip coffee does not have pressure like a coffee machine to extract, it is easy to cause water accumulation in the coffee bed and fail to filter the coffee liquid. In addition, the filter paper or filter plate of ice drip is generally at the bottom, unlike a coffee filter cup which also has venting ridges, so after the coffee grounds are soaked in water, the degassing effect is also affected, and at this time the entire coffee puck will be unevenly extracted.
3. Pre-wetting
Using ice water to "pre-soak" is actually similar to the blooming process in pour-over, which can improve the extraction effect and consistency of the final product. Under the low-temperature and filtration-form extraction of ice drip, direct ice dripping may cause uneven wetting of the coffee bed, with part of the coffee grounds over-extracted while another part does not participate in extraction at all. Pre-wetting in advance can also save production time.
4. Place a round filter paper on top of the coffee chamber
This reserves enough pre-soaking and venting space for the coffee, and the extracted coffee flavor is more complete and clean. After leveling the coffee grounds, we will place a piece of filter paper on top of the coffee grounds. This can increase the contact area between water droplets and coffee grounds and ensure uniform extraction. When water droplets fall and touch the coffee grounds, the surface of the coffee grounds will slowly be dripped into a small pit, and the water flow will follow this small pit downward instead of spreading out to the surroundings. Therefore, the coffee grounds in the entire powder bottle will not be completely saturated, which also causes insufficient extraction. Placing a layer of filter paper will avoid this situation.
5. Find the right coffee grind size
The grind size of Front Street ice drip coffee has a passing rate of 80-85% on the China No. 20 standard sieve. We all know that if the coffee grounds are ground too coarse, the coffee taste will be weak, and if ground too fine, the coffee will be strong and bitter. Similarly, if the coffee grounds are too coarse, there will be no flavor, while if the coffee grounds are too fine, it is easy to form blockages that prevent normal drainage and then make the coffee bitter, so choosing the right grind size is very important.
This time, the refreshing Kenya Little Tomato coffee beans are used for production. At low temperatures, the extraction rate is lower, so Front Street recommends using a slightly finer grind size than pour-over. Here, the passing rate on the China No. 20 standard sieve is 82%. For the store's EK43S grinder, the setting is 9.5; for the C40 hand grinder, the setting is 20-22 clicks.
6. Control the drip speed and coffee-to-liquid ratio
This is the same as the flow rate in pour-over, but the flow rate of ice drip is calculated by the number of drops per second. The slower the flow rate, the longer the total time required, and it is also prone to over-extraction. Front Street generally uses 7 drops every 10 seconds for extraction. Everyone can adjust the flow rate according to their own preferences. The coffee-to-liquid ratio is 1:10. Since Front Street's ice drip coffee is served diluted with ice cubes, a higher concentration is used. If made at home, you can extract at 1:12-1:14.
Front Street makes ice drip by grinding 60g of coffee beans into powder, placing a round filter paper in the coffee chamber, pouring in the coffee grounds, and finally placing another filter paper on the surface, then wetting the coffee grounds with water, which can save drip time and avoid uneven extraction. Fill the upper pot with an ice-water mixture, that is, ice and water at 1:1, to extract a total of 600g of coffee liquid.
7. Drink after refrigeration
Front Street generally pours the finished ice drip coffee into a glass bottle with a sealing gasket, puts it in the refrigerator, and lets it sit for 12 hours before drinking. Pouring it into a glass bottle can mix coffee liquids of inconsistent concentration, and choosing a container with good sealing performance can ensure it is not contaminated by the outside world. The surface of the refrigerator may look clean, but in fact there are many microorganisms that are difficult to see with the naked eye.
Placing it in the refrigerator for 12 hours of low-temperature fermentation will give the ice drip coffee an aromatic fermented aroma, and the original flavor also becomes richer. Fermentation is very common in daily life. Uncontrolled fermentation will cause food to spoil and deteriorate. In a low-temperature environment, this process can be effectively slowed down, and Front Street has also verified that the ice drip coffee made from most coffee beans is most delicious after 12 hours of chilling.
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The above content is compiled by CoffeeHunters, a coffee news website.
