A Short and Sweet History Lesson
Although the cold brew coffee craze has been a recent discovery for most, the methodology has been around for some time.
Depending on which history books you read, coffee consumption dates back to before 1,000 A.D. It was believed that originally it would have been eaten like a berry, not brewed in water to extract the bean’s additional qualities.
Before 1,700 A.D. coffee grounds were typically left in the actual drink – yuck.
In 1908, a German housewife named Melitta Bentz created the paper filter for brewing drip coffee – which is still the way most people consume coffee around the globe to this day! (Ref 4)
In 1964, Todd Simpson developed the Toddy cold brew system. He was a chemical engineering graduate at Cornell and found that when coffee is brewed at higher temperatures, compounds are released that lead to unpleasant flavors in your coffee.
There are certain fatty acids and oils that are only soluble at higher temperatures (roughly 200 degrees F). By soaking the coffee in cold water, the beans are never exposed to those higher temperatures. (Ref 1)
So when you boil it down (see what I did there) brewing coffee at colder temperatures extracts the flavors of the coffee beans while leaving the unwanted oils and acids behind.
Unfortunately, most of you are familiar with these oils as they’re commonly known as the “bite” one must suffer through when drinking a cup of coffee – uh, the agony! This is why most people put sugar and cream/milk in their coffee, to lessen that acidic taste.
It's All About Chemistry
If cold brew coffee is using the same materials such as water and coffee when brewing it hot, how can it really taste that different?
Which type of roasted beans you use and how it is ground impacts the final taste of your coffee, but the biggest impact is from the way it is brewed.
When coffee beans and water mix, there are a lot of chemical reactions taking place in order for your wonderful cup of coffee to get made. These reactions help to pull solubles from the grounds – which in turn gives the coffee it’s familiar taste and smell.
These solubles dissolve best between 195 to 205 degrees F – so coffee brewed with hot water pulls these chemicals out of the grounds quickly. They also evaporate easier, giving you that sweet smelling aroma from a fresh pot of hot coffee.
Having increased solubility isn’t always good. The boiling water forces the chemical compounds of the coffee to oxidize and degrade. This is why hot coffee is known to have a sour and bitter taste.
Oxidation still happens with cold brew, but at a much slower pace. This is why cold brew coffee almost never has that acidic taste commonly associated with coffee.
Cold brew coffee can also stay fresher for much longer than hot coffee – lasting anywhere from 2-4 weeks if refrigerated and stored properly. (Ref 3)