How to Brew Coffee with Cold Water? The Impact of Cold Water Brew Time on Flavor

Professional Coffee Knowledge Exchange

Previously, iced coffee was mostly made by Japanese iced pour-over, ice drip, or cold brew, and relatively few people used ice water for pour-over. Today, FrontStreet Coffee explores how long the bloom should last when you brew pour-over with ice water.

Ice Water Pour-Over

Ice water pour-over, as the name suggests, is brewing coffee with ice water. Coffee grounds extract very slowly at low water temperatures: cold brew needs at least 12 hours in the refrigerator, and ice drip takes 6-8 hours.

Since pour-over normally takes only a few minutes, FrontStreet Coffee follows two tactics when brewing with ice water: adjust the grind to BG 6M (72% pass rate through a China standard #20 sieve), and use hot water for the bloom, extending the bloom time to raise extraction from the grounds.

That raises the question: how long should the bloom be for the best result?

Bean Information

For today's test, FrontStreet Coffee selected Kenya Othaya FCS Chinga Factory Natural. The natural process gives this bean a rich, complex fruity acidity, and it is very refreshing as a Japanese iced pour-over. How would it taste as an ice water pour-over?

Kenya Othaya FCS Chinga Factory Natural
Kenya Othaya FCS
Region: Nyeri, Kenya
Processing: Natural
Altitude: 1700-1950 meters
Varieties: SL28, SL34
Grade: AA

Experiment in Progress

Because FrontStreet Coffee wanted to compare only the effect of bloom duration on flavor, all other parameters stayed the same. Changed bloom times meant the extraction time was extended accordingly. To keep errors to a minimum, no additional agitation was used beyond the stirring caused by the water stream itself.

Parameters and technique: 15g coffee dose; water temperature: 90 degrees Celsius hot water, 0 degrees Celsius ice water; grind size: BG 6M (72% pass rate through a China standard #20 sieve); coffee-to-water ratio: 1:15

Bloom with twice the coffee weight in 90 degrees Celsius hot water. After blooming, add 0 degrees Celsius ice water to 122g for the first segment. Continue pouring to 227g when the water level is about to expose the coffee bed. Remove the filter cone when the bed is about to show again.

[One Minute Bloom]

Timing started at the bloom. Total extraction time: 3'35".

Flavor notes: cherry tomato and lime acidity, with honey and cream sweetness. Overall quite sweet and acidic, but with a slight under-extracted astringency.

[One Minute Thirty Seconds Bloom]

Timing started at the bloom. Total extraction time: 4'05".

Flavor notes: dried plum acidity, with mango and lemongrass flavors. The aftertaste has creamy and floral notes.

Comparing the two batches, FrontStreet Coffee found that the one minute bloom version, while sweet and acidic, showed slight astringency and somewhat thin flavors; the one minute thirty seconds version had more pronounced sweetness and a pleasant aftertaste.

Conclusion

Extending the bloom time increases extraction from the grounds to a certain degree.

If you want to try ice water pour-over, FrontStreet Coffee suggests improving extraction either by extending the bloom or by adding agitation during brewing.

Regarding making ice water pour-over, FrontStreet Coffee has several recommendations:

1. Because ice water extracts so little, you can grind finer to raise extraction. Since finer grounds slow the flow through the filter cone, you can also add water-flow agitation during brewing.
2. It is best to prepare two pour-over kettles, because you need hot water for the bloom and ice water for brewing.
3. During the bloom phase, use hot water to bloom and degas. The water temperature and amount can be a little higher and larger than for a normal pour-over. The bloom can be extended until all the hot water has drained, and during degassing you can also use external agitation to make sure all the grounds are fully degassed.

That is all for FrontStreet Coffee's small exploration of ice water pour-over today. Give it a try.

END

FrontStreet Coffee Recommendation

Cold methods, whether ice water pour-over, ice drip, or cold brew, tend to amplify floral and fruit notes while muting woody and roasty flavors, so light-to-medium roasts give the best results. FrontStreet Strawberry Candy is a strong choice: it combines Panama Geisha with Costa Rican honey-processed beans, so one component supplies delicate rose and orange while the other contributes grape, raisin, blueberry, and strawberry-gummy sweetness. Cold brewed, it is sweet and lively, and left to rest it takes on a soft fruit-wine depth.

For a floral iced coffee, FrontStreet Sun-Dried Flower Queen is the pick. Grown in Ethiopia and naturally processed, the beans absorb sweetness from the fruit during drying, so cold brew shows magnolia, cream strawberry, mango, guava, and black tea. If you want a fuller, juicier cup, FrontStreet Kenya Cherry Tomato brings cherry tomato, snow pear, black plum, and smoked plum over bright, low-bitterness acidity, its SL28 and SL34 varieties and K72 double-washed processing making it especially clean over ice.

Cold brew also uses more coffee per serving than pour-over, so FrontStreet suggests an economical base bean and building in flavor through blending. A good example is FrontStreet's Colombian single origin, rich in passion fruit, grape, apricot, and dried-fruit sweetness, blended 1:2 with FrontStreet Costa Rica Tarrazu for a bright citrus lift at a better price.