Cold Brew vs Iced Coffee

Coffee served cold is gaining popularity on hot and cold days alike. Whether the beverage is called iced coffee or cold brew, they both offer a more refreshing experience than a traditional hot cup of coffee. But what exactly is the difference between the two and why does everyone seem to be raving about cold brew, even in these cold winter days? The difference between these cold coffee beverages lies in the temperature of the water used to brew the coffee.

Iced coffee is just hot coffee served over ice. Cold brew is brewed in cold water. Hence, the latter beverage is named after the temperature of the water used to brew the coffee – not from the temperature at which the beverage is served!

Brewing coffee, scientifically speaking, is the process of using water to dissolve the soluble components of roasted-and-grounded coffee that give the coffee beverage its distinctive smell and taste. During the brewing process, some components change into gases, releasing the coffee’s aroma, while other components transform into liquids, releasing the coffee’s flavor. Different components dissolve more easily than others and are therefore released at different temperatures and after being in contact with water for varying periods of time. 

Cold brew uses time to compensate for the lack of heat to extract the soluble compounds in coffee. Hence, cold brew is often made overnight and brewing times are typically measured in hours or even days, as opposed to the seconds or minutes used to time the brewing of hot coffee. These differences in brewing temperature and time make a huge impact on the flavor, caffeine level and shelf life of your cold coffee beverage, as summarized in the table below. 

Hot water releases chemical compounds in coffee relatively quickly, which means the volatile compounds that evaporate into the air create a more aromatic experience for iced coffee as compared to cold brew, which has a mild smell characterized by sweet chocolate and nutty tasting notes. Similarly, certain bitter and acidic components do not get released in the cold brew process due to the water’s low temperature. As a result, acidity and bitterness are just about undetectable in the final cold brew product, producing a smoother, milder and naturally sweet taste. Just don’t let the smooth flavor foul you. The longer brew time gives water more time to extract more caffeine from the coffee grounds, and longer contact water therefore also means cold brew has a much higher caffeine content.

Oxidation occurs more quickly at higher temperatures, causing hot coffee and iced coffee to turn sour, stale and bitter more easily. As a result, we recommend consuming your hot brewed coffee within an hour, and no more than 24 hours if refrigerated immediately after brewing to prevent the beverage from turning sour, stale and bitter from oxidation. Cold brew, on the other hand, remains fresh, even after two weeks from brewing if stored refrigerated! 

In summary, cold brew has gained a lot of popularity given its smoother and sweeter tasting notes as compared to hot and iced coffee. Cold brew, however, cannot be produced “on demand.” Thus, the planning and time required to prepare this cold beverage also means that cold brew is often sold at a premium at coffee shops, and the more desirable tasting notes have made it a growing segment in the ready-to-drink market served by grocery stores. There will always be a place and time for hot, iced and cold brew coffee. It is just fun to understand the differences and the science behind each coffee beverage. This knowledge also helps us make more informed decisions next time we choose our coffee beverage!