Hot vs Cold Brew Coffee: Unveiling the Science Behind Flavor and Aroma

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The best part of getting up is hot coffee in my cup (with creamer). But, come high noon, I opt for a homemade iced coffee or cold brew. Which got me thinking—how does the brewing process affect how my coffee tastes? Which tastes and smells better? Hot brew or cold brew?

The beans start out the same, right? And yes, it’s clear that the brew method impacts the final flavor, but I needed to know WHY. So I decided to Google it.

Scroll down to see what I found out.

Hot Brew or Cold Brew – Which Smells & Tastes Better?

Here’s what I discovered: In a 2022 study1, researchers investigated the impact of hot and cold brewing on coffee’s flavor profile. Their findings provide valuable insights into why hot coffee tastes distinctly different than cold brew. Let’s dive in.

The Study

The research was carried out by experts from the National Engineering Research Center for Fruit and Vegetable Processing, the Chinese Academy of Agricultural Sciences, and other institutions. They used both chromatographic and sensory approaches to evaluate the effects of the brewing process on coffee’s flavor.

Which Tastes Better Hot Coffee Or Cold Brew According To Science

The nerds applied gas chromatography-mass spectrometry—a machine that heats up a sample and turns it into gas so its individual parts can be studied—and odor activity value calculation techniques (methods used to measure the strength of different smells) to analyze the aroma profile of coffee produced by hot and cold brewing methods.

Plain English: Nerds from several research institutions studied how brewing affects coffee’s flavor. They used special techniques and machines to heat up the coffee and examine its parts, focusing on how it smelled when brewed hot or cold.

Key Findings: Aroma

Interestingly, their findings revealed that most pyrazines—compounds that contribute to the aroma of coffee—were found in higher concentrations in cold brew coffee than in hot coffee. So if you’ve ever noticed a unique, slightly different aroma wafting from your cold brew, this could be part of the reason why.

This infographic shows the scent profiles (inner-most ring) and how they correspond to the specific compounds.

Hot Brew Or Cold Brew
Aroma-active compounds identified using OAV > 1 in hot and cold brew coffee.

Key Findings: Flavor

The researchers also used a method called liquid chromatography, which helps separate the different parts of a liquid, to find 18 unique non-volatile compounds—compounds that don’t easily turn into gas and can affect the flavor of coffee—in the coffee.

Contrary to what you might think, most of these compounds were found in lower amounts in cold brew coffee compared to hot brew coffee. This level difference can change how the coffee tastes when you drink it.

Cold brew coffee smells better than hot brew

Sensory Evaluation

As for the sensory evaluation, the study found that cold brew coffee exhibited higher fruitiness and lower bitterness and astringent notes than hot brew coffee. This could be attributed to the presence of certain compounds, including linalool, furfural acetate, and quercetin-3-O-(6″-O-p-coumaroyl) galactoside (that’s my first daughter’s name, btw). So, if you prefer a less bitter, more fruity coffee experience, cold brew might be the way to go.

TL;DR: The study showed that cold brew coffee tastes fruitier and less bitter than hot coffee, thanks to certain compounds.

Best Beans for Cold Brew

For optimal taste and flavor, using high-quality coffee beans when preparing iced coffee is essential. If you prefer dark roasts, I highly recommend Spirit Animal Coffee. My second-favorite beans for cold brew are the Espresso Dark Roast from Volcanica.


In conclusion, how coffee is brewed dramatically changes its taste and smell. Both hot and cold brew methods yield distinct results due to different chemical reactions. So, whether you enjoy the warmth of a hot coffee or the cool refreshment of a cold brew, consider the science behind every sip. The flavors you experience are the result of complex interactions among various compounds.

If you’re intrigued by the science behind coffee brewing and would like to further explore the intricacies, the book “Coffee: A Comprehensive Guide to the Bean, the Beverage, and the Industry” by Robert Thurston, Jonathan Morris, and Shawn Steiman is a fantastic resource. It takes a deep dive into coffee’s history, culture, production, and its fascinating journey from bean to cup.

In the end, though, it’s all about personal preference. The beauty of coffee is its versatility – hot or cold, black or with creamer, sweet or unsweetened. Whether you’re a fan of the intense aromatics of a piping hot brew or the subtle fruitiness of a cold brew, your enjoyment is what ultimately matters most.

Iced Coffee
Iced coffee

Further Reading

For those who are interested in reading the full study, you can access it here.


  1. Cai, Y.; Xu, Z.; Pan, X.; Gao, M.; Wu, M.; Wu, J.; Lao, F. Comparative Profiling of Hot and Cold Brew Coffee Flavor Using Chromatographic and Sensory Approaches. Foods 2022, 11, 2968.
Avatar Of Kelsey Todd
With over two decades in the coffee industry, Kelsey is a seasoned professional barista with roots in Seattle and Santa Barbara. Accredited by The Coffee Association of America and a member of The Baristas Guild, he combines practical expertise with a profound understanding of coffee's history and cultural significance. Kelsey tries his best to balance family time with blogging time and fails miserably.

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