Cold brew has earned a permanent place in the specialty coffee world. Far from being just a summer trend, this extraction technique reveals a fascinating chemistry that produces a beverage with a unique sensory profile: lower acidity, naturally sweet, and with a velvety body. But what exactly happens when we swap hot water for cold? And how can you prepare quality cold brew at home?
What is cold brew, exactly?
Cold brew is an extraction technique where ground coffee steeps in room-temperature or refrigerated water for an extended period, typically between 12 and 24 hours. Unlike traditional iced coffee, which is simply hot coffee cooled down with ice, cold brew never comes into contact with hot water at any stage of preparation.
This distinction is fundamental because water temperature determines which chemical compounds are extracted from the beans and how quickly that extraction occurs.
The chemistry of cold extraction
Temperature and solubility
Hot water acts as an aggressive solvent. When we brew coffee by traditional methods at temperatures between 90 and 96 degrees Celsius, the water rapidly extracts a wide range of compounds: chlorogenic acids, oils, sugars, caffeine, and bitter compounds. This efficiency comes at a cost: some of these compounds, especially certain acids and volatile oils, can impart harsh or excessively bitter notes when over-extracted.
In cold extraction, water at low temperatures dissolves compounds selectively and gradually. Chlorogenic acids, the main contributors to perceived acidity in coffee, are significantly less soluble in cold water. Studies published in Scientific Reports indicate that cold brew can have up to 67 percent lower titratable acidity compared to hot-brewed coffee made with the same beans.
Oils and aromatic compounds
The oils present in coffee, such as the diterpenes cafestol and kahweol, also behave differently in cold extraction. Since these lipids are less soluble at lower temperatures, cold brew tends to have a cleaner, less oily body than coffee prepared in a French press, for example. This produces the smooth, silky texture that characterizes the drink.
Volatile aromatic compounds, on the other hand, are less preserved in cold brew, since there is no heat to release them during preparation. The result is a more subtle aromatic profile, with notes of chocolate, caramel, and dried fruits predominating over floral and citrus notes.
What about caffeine?
Contrary to a popular myth, cold brew does not necessarily contain more caffeine than hot coffee. Caffeine is quite soluble in both hot and cold water. What influences the final concentration is the coffee-to-water ratio and the extraction time. A concentrated cold brew (1:8 ratio) will have more caffeine per milliliter than a pour-over, but when diluted for consumption, the concentration evens out.
Recommended ratios
Controlling the ratio, meaning the proportion between coffee and water, is the most important factor for good cold brew. There are two main approaches.
Concentrate (1:8 ratio)
Use 1 gram of coffee for every 8 milliliters of water. For example, 100 grams of coffee for 800 milliliters of water. This method produces a concentrate that should be diluted before consumption, typically at a ratio of 1 part concentrate to 1 or 2 parts water, milk, or another base. The concentrate can be stored in the refrigerator for up to 14 days without significant quality loss.
Ready to drink (1:15 ratio)
Use 1 gram of coffee for every 15 milliliters of water. For example, 60 grams of coffee for 900 milliliters of water. This method produces a beverage that can be consumed directly, without dilution. The result is lighter and more refreshing, ideal for those who prefer more subtle flavors.
Grind size and time
For both ratios, use a coarse grind, similar to raw sugar crystals. Finer grinds can cause over-extraction and cloudiness in the beverage. The ideal extraction time ranges between 16 and 20 hours in the refrigerator, or 12 to 14 hours at room temperature. After steeping, filter using a cloth filter, paper filter, or French press.
Summer recipes
Cold brew tonic
The cold brew tonic is a surprising combination that balances the subtle bitterness of coffee with the effervescence and quinine of tonic water.
Ingredients:
- 120 ml cold brew concentrate
- 200 ml premium tonic water, well chilled
- Ice to taste
- Sicilian lemon slice for garnish
Preparation: place ice in the glass, slowly pour in the tonic water, and finish by adding the cold brew concentrate on top. The coffee will create visual layers before mixing. Garnish with the lemon slice. Do not stir: the gradual integration is part of the experience.
Cold brew with fruits
The low acidity of cold brew makes it an excellent base for fruit combinations, creating complex and refreshing drinks.
Ingredients:
- 200 ml ready-to-drink cold brew (1:15 ratio)
- 4 ripe strawberries
- 3 fresh basil leaves
- 15 ml simple syrup (1:1 sugar and water)
- Ice to taste
Preparation: muddle the strawberries with the basil and syrup at the bottom of the glass. Add ice and pour in the cold brew. Stir gently. You can substitute the strawberries with peach, passion fruit, or mango, adapting to seasonal fruits available in the region.
Homemade nitro cold brew
Nitro cold brew is a nitrogen-infused version that produces a creamy texture and a dense foam similar to a stout beer. It is possible to create a simplified version at home.
Ingredients:
- 500 ml cold brew concentrate, well chilled
- Whipped cream siphon with N2O chargers
Preparation: pour the cold brew concentrate into the siphon. Close and charge with one N2O capsule. Shake vigorously for 30 seconds. Let it rest for 1 minute. Dispense into a glass, holding the siphon inverted. The result is not identical to professional nitro, which uses pure nitrogen, but the creamy texture is surprisingly similar.
Tips for perfect cold brew
- Choose medium or medium-light roast beans, which preserve sweetness and complexity during cold extraction.
- Use filtered water. Since the coffee is in prolonged contact with the water, any undesirable flavor will be amplified.
- Experiment with varying extraction times in 2-hour increments to find your ideal point.
- Always store in the refrigerator after filtering.
- Taste the concentrate before diluting: this helps calibrate the desired strength.
Why cold brew pairs perfectly with specialty coffee
Specialty coffee beans, scoring above 80 points on the SCA scale, possess complex sensory profiles that express themselves differently in cold extraction. Notes of chocolate, red fruits, caramel, and nuts that might be masked in an intense espresso gain clarity and definition in cold brew. Furthermore, the absence of excessive acidity allows the natural sweetness of the bean to manifest fully.
If you are visiting Foz do Iguacu and the spectacular Iguazu Falls, cold brew is the perfect way to cool down after a day of exploring. The Triple Border region where Brazil, Argentina, and Paraguay meet offers a unique cultural blend, and specialty coffee is part of that experience.
Visit Consciencia Cafe and discover our cold brew, prepared with carefully selected specialty beans. In the warmth of the Triple Border, there is no better combination than quality coffee extracted cold.