Can coffee be reheated once it has gone cold?

Reheating cold coffee is possible, but it will not taste like a fresh cup. As coffee cools, the taste buds register more sourness and bitterness, and volatile aroma compounds escape into the air. Front Street Coffee compared a light-roast pour-over and a medium-dark-roast Aussie white, cooling and then reheating each to measure the gap against a freshly made cup.

The difference comes down to temperature and chemistry. Heat suppresses the perception of sour and bitter notes, so a hot cup reads sweeter; once it drops, that balance shifts, and a light roast turns more sour while a darker roast turns more bitter. This is why a reheated latte is bitter and thin rather than rich, even if the milk is warmed again gently.

When the weather turns cold, coffee cools down especially quickly, and many customers ask: can it be reheated? Before answering this question, we need to first understand what actually happens after coffee cools down. Temperature affects the taste buds' perception of sweetness, sourness, and bitterness, and also causes volatile flavor compounds to gradually dissipate. This time, Front Street Coffee specifically conducted a comparative experiment, using a light-roast pour-over and a medium-dark-roast Aussie white, letting them cool separately and then reheating them, to see how much difference there is between the reheated coffee and the freshly made, fully cooled versions. The experimental results can help you make a more rational decision in winter about whether this cup of cold coffee is worth reheating.

Besides the cold, the drop in temperature also brings us a whole bunch of problems, such as under-extraction, difficulty sensing the temperature when steaming milk, it getting cold before you even drink it, and so on. One question that Front Street Coffee stores have recently received more often from customers is: "Boss, this coffee has gone cold! Can it be reheated?"

Very good. Before answering this question, let's first review what changes happen after coffee cools down! 1. Changes in taste Our taste buds perceive different flavors as the temperature changes! When coffee is at a relatively high temperature, the perception of sourness and bitterness is relatively low. So when we drink coffee at a higher temperature, we can experience a fuller sense of sweetness.

And when the temperature drops, the perception of sourness/bitterness returns, and the suppression by one of the two lowers the sweetness, so depending on whether the beans used are light or dark roast, this cup of coffee will become a coffee that leans sour or leans bitter! Changes in flavor As we often say, coffee's flavor belongs to a type of volatile substance. So, as time passes, the flavor will gradually volatilize and be lost. After the temperature drops, this cup of coffee inevitably has fewer flavor compounds than when it was hot, so there is not much of an experience to be had!

From these two points, we can determine that even if the coffee is reheated, it will be hard for it to return to being as delicious as when it was just made (in terms of flavor)! But if you are not particular about flavor and just want to restore it to a high temperature, will it taste better and provide a better experience than cold coffee? This is the goal of our experiment this time! Experiment description This time, Front Street Coffee will make a pot of pour-over coffee using light-roast beans and a cup of Aussie white using medium-dark-roast beans (not too much milk foam, so the changes can be felt more directly). They will be set aside to cool, and after they drop to room temperature, half will be taken out and reheated to the temperature of when they were just made, to see what difference there is between the reheated coffee and the cold coffee! Beans used for pour-over: Guatemala · New Oriente Geisha Dose used: 15g Coffee-to-water ratio: 1:15 (225ml) Brewing water temperature: 92°C Brewing method: three-pour method Dripper used: V60 The New Oriente Geisha used this time has flavor notes of sweet orange, white orchid, and honey! And the beans used for espresso are our old friend: Warm Sun Blend, with butter cookie, vanilla, cream, and whiskey as its flavor characteristics. After production was completed, the pour-over coffee's temperature was 67°C, and the Aussie white's temperature was 55°C. We tasted each separately, then waited for them to cool!

After waiting for more than an hour, the temperature finally dropped to room temperature.

Then, we can begin our reheating stage! Pour half of the latte into a milk pitcher, and half of the pour-over into the lower pot of a siphon, and use a heat source to heat them in turn. Once they return to the temperature at which they were just made, you can stop!

(Taking pour-over as an example, from left to right: just made, after cooling, during reheating) Tasting experience of the pour-over coffee

When just made (67°C): It had a very obvious orange sweetness, white orchid aroma, and a thick mouthfeel, and at this point the acidity was relatively soft. When left to cool to 29°C room temperature: There was almost no aroma, and the whole cup of coffee became "rather sour tea," with an obvious tea-like sensation, relatively prominent acidity, and a bit sharp! When reheated back to 60°C: The prominent sourness, as expected, became a bit milder, and the overall cup was not so sharp. Although it was not as delicious as when just made, it was easier to drink than the cooled coffee. Tasting experience of the Aussie white

When just made (55°C): The mouthfeel was mellow, with chocolate, whiskey, and butter cookie flavors very obvious, the milk and coffee very balanced, and a high level of sweetness! When left to cool to 29°C room temperature: Because the blend contains a red cherry bean with berry flavors, at this point the Aussie white showed a bit of sourness, though overall it was still mainly chocolatey. Compared with when it was just made, the difference was an added hint of sourness. When reheated back to 55°C: That hint of sourness disappeared again. Because it contains milk, compared with when it was just made, the whole cup was only lacking some flavor and was not greatly affected.

From this result, we can see that reheating can indeed reduce the unpleasant experience of coffee to a certain extent. But this is under the condition that the beans have no obvious defects! If the beans you use show obvious negative flavors after cooling (bitterness, hay-like taste, and so on), then even if you reheat it, its negative sensations will not be reduced!

The reason is that too much chlorogenic acid is released. Chlorogenic acid is easily soluble in water, but the chlorogenic acid lactones decomposed from chlorogenic acid are difficult to dissolve in water, and raising the temperature cannot solve this situation. So, reheating can indeed restore a certain sense of experience, but it needs to be done according to the beans~

Front Street Coffee

No. 10, Bao'an Qian Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

The above content is compiled by CoffeeHunters, a coffee news website.