Why is My Cold Brew Too Weak? How to Make Cold Brew Coffee? What Parameters Make the Best Tasting Coffee?

Cold brew coffee is arguably the simplest coffee brewing method. Just grind the beans, add water, and wait for a period of steeping and extraction, and you'll be able to enjoy fresh and delicious cold brew coffee.

However, recently FrontStreet Coffee has received many inquiries from friends who, despite using a higher coffee-to-water ratio to make cold brew, find that no matter how they adjust it, the extracted cold brew coffee tastes very weak. They then start considering whether it's an equipment issue and prepare to buy professional cold brew bottles. Wait! Actually, you don't need to. Today, FrontStreet Coffee will share a little trick that not only eliminates the need to spend a lot of money on cold brew bottles but also perfectly extracts a cup of cold brew coffee with excellent concentration! But before that, FrontStreet Coffee will first explain why the brewed cold brew coffee turns out so weak!

The Grinding Issue - But Not Entirely

Actually, FrontStreet Coffee shared this two months ago: in our understanding, the finer the coffee grind, the larger the surface area exposed to water, allowing water to better extract the flavor compounds from the coffee. However, cold brew is quite different because the process of making cold brew coffee is a lengthy static steeping process. Although fine grinding allows the coffee to obtain sufficient extraction at the beginning, over time, the coffee grounds will gradually absorb water and sink to the bottom.

The Key Point

The first to become saturated with water are often the finest particles with the smallest diameter, so they quickly sink to the bottom due to saturation. Then! These fine particles will clump together, forming large particles that are impermeable to water. As subsequent particles sink and cover them, after a period of time, water can no longer extract the coffee grounds at the bottom. Because the gaps are too small, water can only contact the surface layer of the bottom coffee grounds, significantly reducing extraction efficiency. This situation is particularly fatal for light-roasted coffee beans because their high density causes them to sink to the bottom quickly, and due to fine grinding, they generate a large amount of fine particles. Even if the grind is adjusted to be coarser, it's unavoidable to extract a pot of coffee with poor concentration. Unless you use a larger amount of coffee grounds, where quantity can overcome quality. So, if you don't want this situation to occur, you might consider adding a small tool when preparing cold brew coffee - it's the "non-woven tea filter bag"! Yes, you heard that right - it's about wrapping the coffee grounds in a tea bag and then steeping!

Brewing Coffee with Tea Bags? Is It Really Feasible?

Previously, FrontStreet Coffee shared that placing coffee grounds in tea bags for steeping can easily lead to under-extraction. However, this situation only applies to short-term steeping. For long-term steeping, using tea bags to steep coffee grounds actually has more advantages. Let's look at the experiment FrontStreet Coffee conducted below. FrontStreet Coffee prepared two groups of coffee grounds: one group was light-roasted (Elida Catuai), and one group was dark-roasted (Golden Mandheling). Each group was divided into two cups - one used direct steeping of coffee grounds, while the other placed coffee grounds in tea bags before steeping. The grind was one setting finer than normal hot pour-over grinding (8.5 and 10.5 settings on Ek43 respectively), with an extraction time of 8 hours.

(Elida Catuai group)

(Dark-roasted Golden Mandheling group)

As you can see, regardless of which group, the cold brew with direct steeping of grounds and water had a richer color, while the cold brew using tea bags appeared quite "light." But after 8 hours, the color of the cold brew in the tea bag group actually became more intense!

(Golden Mandheling is less obvious) We filtered the two cups of directly steeped cold brew coffee and then measured the concentration of all four cups of cold brew. You'll find that regardless of the group, the concentration of coffee liquid steeped with tea bags is richer than the directly steeped cold brew. (Taking the Elida Catuai group as an example, the left side is direct steeping, the right side used tea bag steeping)

Tasting Results

Through tasting, we confirmed this point very well. The two cups of cold brew coffee made with tea bags were rich and full-bodied, with Elida Catuai releasing sweet honey peach flavors; while Golden Mandheling, due to its less obvious bitterness, revealed soft fruit acidity. Although the entire cup had heavy caramel and spice flavors, the soft acidity gave it a more lively taste and was very delicious. In contrast, the direct steeping group: Elida, due to its high density, as mentioned at the beginning, had all coffee grounds accumulated at the bottom, so water didn't extract the flavor compounds well, making the entire coffee thin and weak; while Golden Mandheling, being dark-roasted, performed better, but compared to the "tea bag cold brew," it was equally thin.

The Principle Behind Tea Bag Cold Brew

The principle behind using tea bags to extract delicious cold brew is simple: because the coffee grounds are contained in the tea bag, they remain contained, so there's no phenomenon of fine particles settling first. Water can only slowly penetrate from outside to inside for extraction, so the external coffee grounds are inevitably the first batch to be saturated by water, rather than all fine particles. Moreover, because the extraction process is relatively slow, the internal coffee grounds won't become saturated quickly. As long as a small amount of coffee grounds isn't thoroughly soaked, the entire tea bag of coffee grounds can continue floating on the liquid surface. At this point, water can continuously extract between the grounds. Because fine particles cannot clump together, they won't reduce gaps and hinder the release of flavor compounds.

Additional Benefits

In addition to ensuring concentration, this method has another benefit: NO! NEED! TO! FILTER! THE! GROUNDS! Although a small amount of coffee grounds may seep through the tea bag into the coffee liquid during steeping, due to their fine particles, they won't affect the overall texture. Not only that, but these small amounts of fine particles can also add richness to the coffee, which can be considered a positive enhancement. Therefore, using tea bags to fill coffee grounds for making cold brew coffee has many advantages. When you feel that the brewed cold brew coffee is too weak, you might try this approach. But remember, when steeping with too many coffee grounds, be sure to divide them into separate bags to ensure water can "reach all parts evenly" and extract the most compounds in the shortest time.

(FrontStreet Coffee's little tip: it's best to buy tea bags with strings, as they will be very convenient when removing the residue at the end)

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FrontStreet Coffee

No. 10, Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473