How does espresso die? Oxidation and degradation

If you let the espresso sit, you won't enjoy it anymore. Why does espresso change flavours so quickly? How does espresso actually die and how long does it take?

Let's start at the end. The death of espresso - what is it?

In this article, I'll talk about the dying of espresso as the stages of its degradation. This is caused by several influences, which we will discuss in more detail below.

In practice, a dying espresso is one that has lost its charm. It lacks its proper flavours, aromas and crema. And this degradation process has an extra fast onset in espresso, which is due to the technology of its preparation in the espresso machine.

How long does it take for espresso to die?

If you let an espresso stand for 30 seconds or 5 minutes, nothing actually changes in its chemical composition. However, as soon as it is extracted, the oxidation process naturally begins. However, this does not have a significant and negative effect on the taste of the espresso until around 10 minutes.

Much faster you will notice that the espresso dies, on thedegradation of the crema. This has been taken as a clear indicator of the quality of the coffee, especially in the past. Today, we know that the original lesson - the more crema, the more espresso - doesn't apply and the crema itself doesn't taste that good.

The changes brought about by the cooling of the coffee are the quickest to take hold. The mouthfeel that we have when drinking espresso, the perception of the coffee flavours, changes depending on the temperature of the drink. Here the "deadline" for consuming espresso is very individual. If you want some estimate of the optimal time to drink espresso, it's within about 10 seconds to 3 minutes.

How does fresh coffee become dead espresso?

Now let's take all three of the above factors defining stale espresso in turn. That is, how aged coffee is affected by oxidation, crema degradation and temperature loss.

Oxidation of the coffee

The initial oxidation reactions in coffee occur before the espresso is even made. In fact, long before a packet of coffee even arrives from the roaster. Oxidation occurs to everything in contact with air. Significant effects of oxidation on the taste of the coffee have already begun in the roastery.

Sure, coffee oxidizes and ages even earlier, but much faster after roasting, and the oxidation process has an even greater rush in the finished coffee drink. Oxygen is the enemy of coffee freshness and espresso succumbs to it in just a few minutes. The rate of oxidation also correlates with the temperature of the coffee.

Oxidation also occurs in the overflow

With batch brew it is preferable to keep the brewed coffee in a thermos rather than gradually reheating it in a kettle. With each reheating, oxidation accelerates here too.

The degradation of the crema

As I said a couple of paragraphs above, thick crema does not necessarily mean good quality espresso. More or less, crema is especially beneficial for creating latte art. In it, it helps with creating the ideal "canvas" for painting and creates the desired color contrast for latte art designs.

In fact, on its own, it isbitter to thetaste. Crema is the foamed coffee oils that create a uniform layer on the surface of the espresso. Although crema is not proof of the quality of the taste, it is part of it. It completes the complex flavour expression of the espresso. The longer you leave the espresso, the more degradation the crema will achieve. Perhaps it is this visual impression of old espresso that gave rise to the concept of espresso 'dying'.

Loss of temperature

In an espresso machine, the temperature during espresso extraction reaches about 92°C. Plus or minus depending on the specific setting. The coffee cools a little on the way to the cup and then to the table, to about 70°C. Some coffee tasters believe that it is better to wait a while before drinking the coffee. until it has cooled to about 55°C.

As the temperature of the drink drops, how our taste buds perceive its palette of flavourschanges. You know when you drink a cola, for example, that warm is unpleasantly sweet as opposed to ice cold. Same drink, just a different drinking temperature. So does coffee. But everyone has a range of preferred flavors somewhere else. So even the time of death of espresso in terms of cooling is relative.

What about the caffeine in old espresso?

The amount of caffeine in a cup of espresso doesn't change over time. If you're all about the caffeine kick and not the taste, feel free to drink an hour-old espresso.

Old espresso in a latte?

Did you know that an espresso that hasn't been drunk right away is great to pair with milk? According to the cappuccino taste test of aged espresso, it's perfectly fine to use 5-15 minute old espresso. Yet the best taste in a milk drink was achieved by the 10-minute one.

How does aged espresso taste?

During the time you don't drink the espresso, theflavors gradually change. At first, there is a pleasant development of sweetness as it cools. But this then turns to acidity. Significant cooling may give way to oxidation and degradation of chlorogenic acid to quinic acid. So coffee shows increasingly bitter flavours.

Let's not forgetevaporation promoting loss of aromas, as aroma has a significant effect on flavor perception. Well, coffee without aroma... not much, right?

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