Good old hot coffee is a classic morning delight that has been widely consumed for centuries now. Cold brew popped up on menus some years ago, and its popularity has been on the rise ever since. So why do these coffee varieties taste so different? We are here to answer that question for you.
Cold brew is often described as being very smooth and full-flavored without any acidity or bitterness. In general, hot brew has a more acidic taste than cold brew and can be harsher in comparison. It also has a stronger aroma.
Hot coffee and cold brew can taste wildly different, even if they are both brewed with the same blend. The reason for this is the brewing process.
Hot coffee can be brewed many different ways, but the end result mostly remains the same due to the water temperature. Hot water quickly extracts coffee from grounds, taking a few seconds up to several minutes to produce coffee. In exchange for this speed, you get more acidity and bitterness in the finished brew.
Cold brew is made differently. Using a 3:1 ratio, large batches of coarsely-ground coffee are steeped in cold water. Usually, the steeping process lasts between 12-20 hours. In any brewing method, the longer coffee steeps, the bolder the flavor. However, you will get a bitter result if coffee is over-steeped. For cold brew, the limit for steeping is 24 hours.
The natural oils and acids in coffee are what gives coffee its recognizable aroma and taste. When water is forced through coffee grounds, it pulls out these oils. The temperature of the water makes a big difference because it changes the oxidation rate.
What is the oxidation rate? When the oils in coffee are exposed to oxygen, that is oxidation. The rate at which this happens partially determines the level of bitterness the coffee has. When hot water is used, such as for hot coffee, more oils and acids are released at a faster rate. When cold water is used, the oxidation is slower, and fewer of the compounds oxidize.
During the slower oxidation in cold brew, some of the compounds attributed to bitter flavors are left behind. This is why cold brew tends to be smoother, less aromatic, and slightly sweeter in flavor than hot coffee.
We have already discovered the main reason cold brew and hot brew taste different: the temperature used during the brewing process and how it affects the oxidation rate. However, there are two other variables that contribute to the differences in taste. These include the roast used and the grind.
Hot coffee can be brewed with any roast you want. Different roasts have different flavor profiles. If the roast is lighter, it will have a mellow, complex flavor, but with more acid. Medium roasts usually taste balanced and can range in flavor from nutty to earthy to floral. Dark roasts have bolder flavor and full body with less acidity. They can contain notes of caramel or smoke.
Cold brew is typically made with dark roast coffee, but can also be made with medium roast. The flavors of these roasts carry over well in a cold brew, giving it low acidity and full body.
Cold brew always uses a coarse grind. In fact, it is considered an extra-coarse grind. The grind used for hot coffee differs depending on the brewing method. To give some examples, a French press uses a coarse grind because it steeps. A medium grind is used for drip coffee makers and pour-overs. Fine grind is for making espresso.
The coarser the grind, the more likely it is you are steeping your coffee. Steeping coffee develops a full flavor for your brew. This is the case in cold brewing and hot brewing. Fine grind can also get a really strong coffee flavor when water is forced through it, which is exactly why it is used for espresso.
Now you don’t have to wonder why there’s a difference in taste between hot brew and cold brew. The most important factor is the temperature of the water when brewing, because that affects oxidation rate and the flavors left behind. Don’t forget that the grind size and the roast used also play their own part. Share the coffee knowledge wealth with others!
Header image credit: T.Tseng, Flickr