As spring ushers in warmer temperatures, the cold brew coffee season is quickly approaching. Small Town Coffee Roasters is eagerly anticipating warmer days when we can enjoy cold brew’s natural sweetness, higher caffeine and literally no bitterness. In anticipation of the coming season, here’s a look at how cold brew coffee is unique.
For the uninitiated, cold brew and iced coffee are actually two totally different coffee based drinks. While iced coffee is brewed to double strength with hot water, cold brew coffee is steeped using cold water for a very long time.
By brewing coffee with lower temperature liquid, (refrigerated, sun brewed, or at room temperature) the coffee ends up producing 67% less acidic than normal hot coffee and has a much sweeter taste. This is great for people with acid sensitivity, sensitive stomachs, or people who desire a jolt of the higher caffeinated cold brew.
Cold Brew Usually Has More Caffeine
"the bitterness of coffee comes mostly from the heat of the water"
Cold brews will definitely contain a higher caffeine content, since it uses a higher coffee grounds to water ratio compared to hot brews. Since cold brews are concentrated though, some people prefer to dilute their cold brew coffee with water or milk, which will ultimately cut down on the concentration of caffeine.
With cold brew, the idea is that the heat is replaced with time - instead of brewing with hot water and achieving instant gratification, cold brew uses cold or room temperature water, so the process takes longer. Here’s the trick - because the bitterness of coffee comes mostly from the heat of the water, the cold brewing process can remove most if not all of the bitter taste and acidity of the coffee. As a result, you get a much smoother and generally better tasting cup of iced coffee than if you had brewed it with a more traditional method. Face it, nobody likes a bitter cup of coffee and this is one of the best ways to remove that bitterness.
Cold brew demands more patience. In a Mason jar, French press, or coffee sock, coffee grounds are mixed with iced or room temperature water, and then left to sit for hours—anywhere from three to twenty-four hours (see chart)—before the solids are filtered out. Our BluMonkey cold brew recipe calls for a higher coffee to water ratio: 1 part coffee to 5 parts cool water, when compared to hot brew which is 1 part coffee to 18 parts water. Once the grounds are removed, what’s left is black coffee concentrate that can be diluted with water or milk before it is served.
The Science Behind Coffee Extraction
Coffee grounds contain a mixed bag of volatile and non-volatile components, such as various oils, acids, and other aromatics. These “coffee solubles” are what gives coffee its flavor. To extract these solubles, we use various brewing processes that use water as the method of extraction - water temperature, time, and grind size are the principle variables.
Temperature affects the solubility and volatility of coffee solubles. These solubles dissolve best at a temperature of 200°F. With more coffee solubles extracted, hot brew coffees are described as more full-bodied and flavorful when compared to cold brew.
On the downside, oxidation and degradation will occur more rapidly at higher temperatures. The oils in coffee solubles can oxidize more quickly at these higher temperatures, causing it to taste sour. Acids can also degrade coffee - most notable is chlorogenic acid into quinic and caffeic acid, causing coffee to taste bitter.
Where cold brew lacks in temperature, it makes up for in time. Increasing the brew time from a few minutes to many hours aims to maximize extraction of the solubles from the grounds. In order to make up for the lower extraction rate, the amount of coffee grounds is more than doubled. Even over twenty-four hours, not all the coffee solubles will have dissolved.
Oxidation and degradation will still occur in cold brew methods, but this happens much more slowly. Bitterness and acidity are just about absent in cold brew coffee, especially if it is kept cold. Fans of the cold brew method have emphasized that cold brews contain a completely different flavor profile that can’t be found with hot brews. Consequently, cold brews take on a much sweeter, floral profile.
Note that brew time does not determine caffeine content, nor does bitterness indicate coffee strength. Caffeine is extracted early in the brewing process, so extending brew time, by either method, will result in over-extracted coffee.
Coffee “strength” is defined as the amount of dissolved coffee solubles per unit of coffee volume. On that train of thought, cold brew certainly produces stronger coffee, given that the brewing process purposely concentrates the coffee solubles.
Complementing Cold Brew’s Sweetness with Milk
Cold-brews are prized for their natural sweetness, which is produced by the cold water’s lower extraction rate. This natural sweetness makes cold-brews perfect for adding cream to. Although you might not think of milk as being sweet, it is full of sugars (e.g. lactose). At Small Town Coffee Roasters, we use locally sourced "Happy Cow Milk." Our milk comes from Homeland Creamery and uses a slow pasteurization known as VAT processing. This type of pasteurization leaves all of the goodness and natural sweetness in the milk, making it especially good for milk based espresso drinks.
With VAT pasteurization, milk is held at 145ºF for 30 minutes and then quickly cooled. This retains a much higher percentage of the milk's natural enzymes and beneficial bacteria which adds to the flavor and health benefits of the milk. The texture is richer and creamier than the usual homogenized HTST pasteurized milk.
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