Benefits: Why Does Cold Brew Coffee Taste Better

Posted on February 20, 2016

There are plenty of guides on the web that show beginners how to make a cup of cold brewed coffee. Few dig into much detail about why one would want to in the first place. In fact, the perceived wisdom for many years was that the sharp, acid taste achieved only through brewing hot was essential to delivering a good cup of coffee^[1]. Some experts even find cold brewed coffee to taste weaker and perhaps even insipid compared to a hot brewed coffee from a traditional espresso machine.

However cold brewed coffee has found particular favor with lovers of iced coffee, because without the acid and bitter elements which are prevalent in a hot brewed coffee, some of the sweeter and smoother flavors are more evident, giving a more refreshing summer drink.

Having said that, cold brew coffee can be stored safely in the fridge, heated in the microwave, or have steaming hot milk added to make many traditional hot coffee beverages, and is gaining favor with many drinkers, particularly those who find themselves unable to drink regular coffee as much as they'd like due to issues with acid reflux.

What Changes The Taste In A Cold Brewed Coffee?

A roasted coffee bean contains many compounds that are extracted during the brewing process. Some of those compounds, including certain oils and fatty acids, are soluble only at a high temperature. During the cold brew process, coffee beans are never exposed to high temperature (this only occurs after a rich liquid coffee concentrate has been produced).^[2]

Put simply, most of the bitter, sharp and acid tastes that are in a traditional coffee come from compounds which cannot dissolve at low temperatures. However since coffee itself is partially water soluble, and so is caffeine, many of the flavors can be extracted at a low temperature. Cold brewing, therefore, results in a thick, concentrated coffee which has a rather different flavor profile to the one most are accustomed to from traditional coffee preparation methods.

It's not just the simple matter of cold brew coffee extracting different chemicals, the resulting coffee drink contains a different mix of chemicals entirely due to the effect of heat on the coffee grounds and the chemical degradation that occurs as a result. So a hot brewed coffee drink not only contains different acids and chemicals because they are easier to extract at a higher temperature, but also contains different acids and chemicals because they are created during the heating process.

On the downside, oxidation and degradation also occur more rapidly at higher temperatures. The oils in coffee solubles can oxidize more quickly at elevated temperatures, causing coffee to taste sour. Acids also degrade, the most notable of which is chlorogenic acid into quinic and caffeic acid, causing coffee to taste bitter^[3]

Maximizing The Benefits Of Cold Brewing For Flavor

Most of the tips and guides we've put together call for using a slightly courser grind when preparing cold brew coffee. This isn't just about solubility or ease of filtration afterwards (you'll notice some really fun tips, including the ability to make an entire cold brew at home with nothing you don't have available, including filtering it with an old t-shirt!) but the fact that the grind itself can change the chemical composition of the resulting coffee drink.

It stands to reason that if one of the issues we're trying to avoid when we cold brew a coffee is that heating the roasted coffee beans again further alters the chemical composition, that we would want to avoid heat at all stages between roasting and brewing. A fine grind often results in the coffee reaching a much higher temperature than in a coarser grind which will result in less of the changes you're looking to avoid when adopting the cold brew process.

Sources:

[1] http://www.thedailybeast.com/articles/2009/08/18/coffees-dirty-little-secret.html
[2] http://toddycafe.com/cold-brew/why-toddy-cold-brew
[3] https://scienceandfooducla.wordpress.com/2014/08/19/coffee-brewing-chemistry-hot-brew-and-cold-brew/