Why doesn't coffee taste as good when it gets cold? How long should you drink it? What's the difference between hot and cold?

When a cup of hot coffee cools down, flavors like acidity and bitterness become amplified, making the entire coffee difficult to drink (not as enjoyable), which is why people generally believe that coffee should not be left sitting for too long. Many friends then wonder: if it can't be left for long, when is the best time to finish a cup of coffee?

To understand within what timeframe coffee should be consumed, we first need to understand why coffee becomes less enjoyable over time. The main reasons are none other than what we commonly refer to as two things: the loss of flavor compounds and the impact on our sensory perception.

Why Does Coffee Taste Worse When It Cools Down?

The aroma that coffee emits is actually a process of volatile compound loss. Although the compounds in coffee don't increase after brewing is complete, they certainly decrease!

Just like carbon dioxide within coffee beans, volatile compounds in coffee continuously dissipate over time. By the time the temperature drops, a significant amount of volatile compounds have already been lost. Even without the influence of sharp acidity or bitterness, in comparison, cooled coffee cannot taste as good as hot coffee due to the lack of volatile compounds!

The second factor is sensory impact, which is a point that FrontStreet Coffee often mentions: our perception of taste changes with temperature. When coffee is hot, our perception of sweetness is higher, effectively suppressing the perceived intensity of acidity and bitterness, achieving balance. That's why when coffee is hot, we don't experience overly stimulating negative sensations. However, when it cools down, our perception of sweetness decreases, leading to an increased intensity of acidity and bitterness perception, which creates the phenomenon of coffee becoming more acidic or more bitter as it cools.

Here's a simple example: you can prepare a cup of hot water, add a little sugar to it, and taste this sugar water at different temperatures. You'll discover that the closer the temperature is to body temperature, the sweeter the water tastes!

The same principle applies to coffee. If you want to experience it at its sweetest and most flavorful peak, finishing it before it reaches room temperature is ideal! However, this temperature drop will vary depending on the surrounding environmental climate, so there's no fixed time point. More accurately, it's best to "drink it promptly."

What About Iced Coffee?

The same principle applies to iced pour-over coffee! Typically, a cup of iced pour-over contains several unmelted ice cubes. Regardless of their size, once these ice cubes melt, the iced coffee will become diluted, reducing its concentration and affecting its flavor (while volatile compounds also continue to evaporate). Therefore, whether hot or cold, it's best to finish your coffee before it "changes in flavor" – that's the optimal answer!

Can Cooled Coffee Be Saved?

So for cooled coffee, is there any way to save it? FrontStreet Coffee conducted a heating experiment on cooled coffee last month, aiming to test whether cooled coffee could regain the deliciousness it had when hot. The results were as we expected: although heating can restore our sensory perception of sweetness and reduce the impact of acidity and bitterness, it cannot retrieve the already lost aromatic compounds, leaving a noticeable gap in flavor! No matter how you adjust it, the lost flavor won't return. So, it's still best to drink it promptly~

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FrontStreet Coffee
No. 10, Bao'an Qianjie, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473