The mistake when preparing cold brew coffee that leaves it with a bitter taste
Cold brew coffee is more refreshing and smooth than traditional coffee, but an incorrectly calculated brewing time can leave it bitter.
“Cold brew should be steeped for 16 to 20 hours to achieve proper extraction and avoid bitterness. The exact time of steeping really is about personal taste and the beans so you may need to experiment.”
Compared to traditional coffee, cold brew coffee can be more refreshing: it has more caffeine than iced coffee and a much milder flavor. Pure cold brew coffee shouldn't taste bitter or acidic unless lemonade is added, so it doesn't need milk or sweeteners to be easy to drink. If it tastes bitter, the problem is usually in the preparation.
Darren Spicer, co-founder of Clutch Coffee Bar, a popular coffee chain in the Carolinas, explains that brewing time is crucial. If left to steep for too long, the coffee becomes bitter. According to Spicer, “Cold brew coffee should be brewed for 16 to 20 hours to achieve proper extraction and avoid bitterness. The exact brewing time depends on personal taste and the beans, so you may need to experiment.” Additionally, coffee brewed in the refrigerator tends to be much less bitter than coffee left on the counter.
Cold brew uses cold or room temperature water, takes longer, but follows the same basic steps. The water extracts flavor, acids, sugars, and plant fiber from the ground coffee beans. If the brewing time is too short, the coffee will be weak; if it's too long, over-extraction occurs, resulting in an unpleasant flavor.
Spicer points out that "bitter" is often used as a catch-all term for any unpleasant taste, when in reality it could be acidic, astringent, or rancid. Other contributing factors include undersaturated or rancid beans, an incorrect coffee-to-water ratio, poorly filtered water, or a grind that is too fine. Brewing time, however, is the easiest factor to control.