<\/span><\/h2>\nBloom is a concept that filter coffee lovers know well: that 30-45 second pre-infusion with a small amount of hot water before continuing the extraction, which helps the coffee release the CO\u2082 accumulated after roasting and lets the water penetrate more evenly. In cold brew, the principle is the same but adapted to cold brewing: before adding all the brewing water, the ground coffee is moistened with a small amount of water (cold or room temperature, roughly 10-15% of the total) and left to rest for 5 to 15 minutes. This prior bloom lets the ground coffee absorb the initial water, ‘open up,’ and release some of the retained CO\u2082, so that when the rest of the water is added the extraction is more even and complete from the start. The result is usually a cold brew with greater flavor clarity, less unnecessary bitterness, and more homogeneous extraction throughout the coffee bed.<\/p>\n
<\/span>What coffee to choose for quality cold brew<\/span><\/h2>\nCold brew amplifies coffee defects just as much as it amplifies its virtues: a low-quality bean doesn’t improve just because it’s infused cold, and its less pleasant notes can become more obvious. Coffees with fruity and floral profiles \u2014natural or honey processed, from origins such as Ethiopia, Colombia, or Guatemala\u2014 work especially well cold, since the low temperature highlights their sweetness and more delicate notes without the bitter compounds that heat can extract. Medium roasts are the sweet spot: very light roasts can come across as too acidic or under-extracted when brewed cold (the solubility of compounds is lower without heat), while dark roasts can turn bitter. The grind should be medium-coarse, similar to a French press: finer than that makes filtration harder and can create astringency; coarser can cause under-extraction and a watery result.<\/p>\n