Hot Brewing Coffee versus Cold Brewing Coffee: Temperature Matters

Could there something deeper going on in your cup that affects the way your hot and cold brew coffee can taste?

You’ve probably noticed that when you cool down your hot coffee, it doesn’t taste quite as good as your favouriteย cold brew coffee. Besides theย temperature, could there be something deeper going on in your cup that affects the way your hot and cold brew coffee canย taste?

Let’s dig a little deeper…

Unlocking the differences: Understanding taste

Disclaimer: I don’t claim to be a professor or doctor, however, I was a registered nurse for many years, and human anatomy and physiology is second nature to me… But I will try my hardest to keep things “light and breezy.”

Now that’s out of the way. Let’s take a little bit of time to understand how we as humans taste things.

In our mouth we have a tongue, on that tongue are “taste buds” AKA as taste receptors. These receptors function as one of the interfaces between the chemical make-up of foods and liquids we ingest and the central nervous system. We’ve known for years that as humans, we have taste receptors for sweet, umami, bitter, and salty. When the food or drink we ingest comes into contact with the taste receptor, the receptor will excite the nervous system, telling our brain what types of flavours we are tasting.ย 

The nuanced differences in the chemical composition of the food or drinks that come in contact with our taste buds will result in different receptors (sweet, umami, bitter, and salty) getting excited resulting in the perceived difference in taste. This is important to know because the chemical make up of hot brewed coffee is different to cold-brewed coffee, which means they are exciting different taste receptors.

Homemade Cold Brew Coffee to Drink for Breakfast

How does the brewing temperature affect the flavour of your coffee?

Hot-brewed coffee and cold-brewed coffee are two very different beasts. While they both might have been made with the same bean, they will taste very different.ย Why?

Well, the temperature you brew your coffee affects how much oils, acids and other goodies get extracted from your coffee. One way I like to think of making coffee like food prep and cooking – after all, coffee is a fresh product too, you know. Let’s take fish for example, most people have had it hot (fish and chips) or cold/raw (sushi). Have you noticed that they taste completely different?

Let’s take it one step further. Have you tried to cook fish without a lot of oil, only to find that when it comes time to plating it up, you’re left thinking, “Damn that’s a lot of oil and fats”? This is because when the fish is heated up during the cooking process the fish contracts. During this process, the oils, acids, sugars and fats are expelled out of the fish and into the pan or onto the plate. This happens for most organic matter when it is heated up. Let’s relate this back to coffee – The fish is the coffee, the frying pan is your brewing temperature, and the oils and fats are your extracts from the coffee.ย 

When you brew coffee with hotter water, it both acts as accelerants to speed up the coffee extraction process and extracts more oils and fewer acids. This results in a more bitter cup of coffee.ย Coffee brewed with cold water is slower and has much longer extraction times. The slower and more gentle extraction has a profound effect on the final flavour of the coffee, as cold water extracts less fatty oils and acids than hot water, which results in a less bitter, and sweeter brew.

Cooling down a hot coffee, its cold brew right?

Wrong! Cooling down a hot coffee is not cold brew, it’s just hot brewed coffee that is now cold. There is a very big difference. As I mentioned above the temperature of the water affects the amounts of oils, acids and goodness that gets extracted from the coffee.

Again lets stick with the fish example. Cooked fish that is now cold is not the same as eating cold/raw fish, you’re just eating cold cooked fish.

Back to coffee – if you’re drinking a hot coffee that is now cold, you are drinking a hot brewed coffee’s extracted chemical compounds cold. This would be different from drinking a cold-brewed coffee cold as you’d be drinking fewer oils and acids which would result in a different taste.

Is cold brewed coffee weaker that hot brewed coffee?

A loaded question right? To answer it, we need to define “stronger.” There are two ways “stronger” could be determined. (1) How bitter the coffee is, or (2) the caffeine content of the final cup of coffee. In my experience (over ten years on the specialty coffee scene and competitions in Melbourne) when a customer uses the word stronger, they usually think bitterness and caffeine strength are the same. This couldn’t be any more wrong.

A coffees bitterness is directly related to heat (during the roasting and brewing process) which allows for the extraction of oils. Think of this like cooking, when you heat your favourite ingredients, the oils that naturally occur inside the ingredients (that gives them flavour) will be released. The same thing happens when coffee beans or grounds are exposed to heat.

The caffeine content, however, is directly related to the length of time. In other words, the longer the brew time, the longer the coffee spends in contact with the water, the more caffeine is extracted.
Because both cold drip and cold brew coffee rely on cold water and no pressure, fewer oils and acids are extracted, allowing for a lighter and more floral drink and minimises bitterness. The slower process means the caffeine content is higher, too.

What does this mean for you? Well, at first, you’ll taste your cold drip or cold-brewed coffee and think “This tastes more like a tea, I can taste the flavours without the bitterness โ€“ it must be weak.” Then 15 minutes later, you’ve got the shakey-hands, and you’ve just smashed out a whole days work.

Summary: Closing thoughts

The flavour of coffee is a combination of extracted oils, acids, residual sugars, as well as caffeine. But the amount of what gets extracts is directly affected by your brewing temperate, and the differing amounts of extracted compounds cause different taste receptors to be excited, resulting in a perceived difference in taste.

Now that we know that there are nuanced differences in chemical make up of the coffee extracts between hot brewed and cold-brewed coffee, it now makes sense as to why they taste very different. As a general rule, the more the acids and oils you extract from your coffee, the more bitter your cup will be. 

So if your cooling down a hot cup of coffee there is no way that you can change or put back any amount of oils, acids, residual sugars as these have already been extracted during the hot brewing process.

I know right? There is a lot to think about when brewing coffee. It can get complex pretty quickly. I guess that’s what happens when you have been in the industry for as long as I have. But I hope this helps to explain things in an easy to digest way.

Make sense?… Hope so.ย If not, don’t worry about it and simply enjoy the cup of coffee the way you like. That’s why we created Beyond Coffee brew bags, so we can enjoy them hot or cold in a simple way. We’ve done all the complex thinking for you, so you can just enjoy your brews.

Beyond Coffee is a great way to discover a new single-origin coffee each delivery. it also makes for a great gift.
No need for expensive equipment, just Pour Dunk and Brew and enjoy your day!

Until next time,
Stay caffeinated!

Posted in Brewing Guides and RecipesCoffee Knowledge

Jon O'Neill    
Written by
Jon O'Neill    29th Oct 2020

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