Why Try Cold Brew Coffee with iGulu?

Cold brew coffee is built around low-temperature, long-time extraction.

Compared with hot coffee, cold brew usually has a smoother mouthfeel, lower perceived acidity, and a more rounded flavor profile. This makes it especially suitable for chilled drinks and ready-to-serve formats.

With iGulu’s temperature control and pressure settings, cold brew becomes more than just coffee steeped in water. The stable low temperature helps support a clean and refreshing extraction, while the pressure mode opens up the possibility of a lightly sparkling texture.

In other words, this experiment was not just about making cold coffee. It was about exploring a colder, smoother, and more playful coffee experience at home.

The Coffee Bean We Used

For this test, we chose a dark roast coffee bean with flavor notes of almond, dark chocolate, and roasted nuts.

This profile works well for cold brew because it naturally leans toward a fuller and smoother flavor direction. The acidity is relatively low, which helps the final drink stay rounded instead of sharp or overly bright.

For this recipe, we wanted the cold brew to feel cohesive, smooth, and easy to drink, rather than bitter or fragmented. To support that goal, we used a coarser grind size than we normally would for faster extraction methods.

A coarser grind helps slow down the extraction process during the long steeping time. This can reduce the risk of excessive bitterness and help preserve a cleaner flavor structure. It also allows the almond, dark chocolate, and nutty notes to come through in a more balanced and integrated way.

Recommended Coffee-to-Liquid Ratio

For this test, we used the following coffee-to-liquid ratios:

• 1:10 for a balanced result
• 1:12 for a lighter and milder version
• 1:8 for a stronger and more concentrated cup

For first-time testing, 1:10 is a good starting point. It gives enough body without becoming too heavy.

How We Made It

The process is simple, but a few details are important.

Grind the Coffee Beans

Grind the coffee beans to a coarse particle size. For this test, we intentionally kept the grind on the coarser side. This helped create a gentler extraction over the long steeping period and reduced the chance of the coffee becoming overly bitter. It also supported the smoother, more integrated mouthfeel we wanted.

Place the Coffee Grounds in a Filter Bag or Filter Container

Put the ground coffee into a cloth filter bag and make sure it is properly sealed. This step is important because loose coffee grounds may enter the liquid and potentially clog the tubing or flow path. A cold brew filter container or filter carafe can also work, as long as it keeps the coffee particles contained. The key principle is simple: keep the liquid clean and reduce loose sediment as much as possible.

Add the Liquid

Pour room-temperature water into the machine, then place the prepared coffee bag inside. Besides the basic water version, we also tested two variations:

• Replacing water with an equal amount of apple juice
• Using a blend of apple juice and jasmine tea

These variations created different flavor layers. Apple juice added fruit aroma and a softer sweetness, while jasmine tea brought a lighter floral note and more aromatic depth. However, when using juice, tea, or other flavored liquids, make sure they are free from pulp, tea leaves, or visible sediment. Any particles may affect the internal flow or increase the risk of clogging.

Set the Machine

Use either:

• CO₂ Cooling Mode, or
• Sparkling Water Mode

Let it sit for 18 to 24 hours. For a more noticeable sparkling texture, you can let it rest a little longer. More time may help the drink feel better integrated and allow the carbonation to come through more naturally.

Flavor and Texture

After 18 to 24 hours, the cold brew is ready to drink.

The result is softer and smoother than hot coffee, with lower sharpness and a more rounded finish. Because we used a dark roast, low-acidity coffee bean, the flavor leaned toward almond, dark chocolate, and roasted nut notes.

Together with the coarser grind, the extraction stayed gentle and controlled. The final drink did not feel overly bitter or aggressive. Instead, it had a more complete, integrated, and smooth drinking experience. For us, that was the most important part of this test. Rather than simply chasing intensity, we wanted a cold brew that felt balanced, comfortable, and easy to enjoy.

Flavor Variations Worth Exploring

One of the most interesting parts of this experiment was replacing water with other liquids.

Apple Juice Version

Replacing water with apple juice added natural fruit aroma and a soft sweetness. It made the coffee feel rounder and more playful, creating a more creative cold drink experience.

Apple Juice + Jasmine Tea Version

Adding jasmine tea to the apple juice brought another layer of aroma. Alongside the coffee’s nutty and dark chocolate notes, the jasmine tea introduced a light floral character. The result felt more layered and unexpected, while still keeping coffee as the base. This is not a traditional cold brew method, but it shows how iGulu can support creative beverage exploration. With the same basic process, changing the liquid can lead to a completely different flavor expression.

A New Idea for the Next Experiment

During the apple juice test, we found that while apple juice brought more fruit aroma and flavor complexity, its sweetness was also quite noticeable.

That led to another idea for a future test: what if we added a yeast suitable for cider-style fermentation?

In theory, fermentation may help consume some of the sugar, reduce the overall sweetness, and introduce new flavor changes. It may also open up the possibility of developing a certain level of alcohol, depending on the recipe and fermentation conditions.

This idea has not been tested yet, so it remains an experimental direction rather than a final conclusion. But that is exactly what makes this process exciting. A simple cold brew test may eventually lead to a completely new beverage concept. Perhaps cold brew coffee, fruit juice, tea, and fermentation can create more possibilities than we first expected.

Important Notes Before You Try