Is a Latte Supposed to Be Bitter, and Does Cooling Change It?

A latte is espresso plus steamed milk, and an Americano is espresso plus water. Neither should taste sharply bitter when the shot is well extracted; bitterness comes from over-extraction or heavy roasting. Temperature also matters, and there is no single rule on drinking either one hot or iced.

As coffee cools, the tongue registers less bitterness and sweetness but more sourness, because quinic acid converts into quinic acid lactone. Aroma also fades as the cup sits. Coffee left overnight can still be drunk if it was stored covered and refrigerated, but it should be poured out if it was left open at room temperature.

Many people hesitate when ordering: should a latte be hot or iced? And how soon should an Americano be finished? In fact, temperature, personal taste, and body constitution all sway the answer, and our senses perceive sourness, sweetness, and bitterness differently at different temperatures. From the perspective of Front Street Coffee, this article clarifies the basic composition of Americano and latte, explains why coffee tastes more sour after it cools and why aroma is lost after sitting for a long time, and also touches on roughly when caffeine takes effect. Finally, it answers a frequently asked question: can overnight coffee really be drunk, and in which cases must it be poured out?

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"Boss! One latte—is it better hot or iced?"

Whether you're a customer who frequents cafés or a barista standing behind the counter, you've probably heard this line countless times. So here's the question: is a latte more outstanding hot, or more appealing iced?

This is inherently a topic with no definitive answer. The climate you're in, the flavor direction you prefer, and your body's tolerance for cold and heat all influence your judgment. What's more, people perceive taste differently at different temperatures. Therefore, there is no single correct answer.

Then some people will follow up with: how long exactly should a cup of coffee take to finish? To discuss this, we might as well first go back to the two most basic items on the menu—

Americano = espresso + water. Americano is usually shortened to Americano (Americano), and in practice it's simply pouring hot water into espresso: the flavor direction is the same as espresso, just diluted by water.

Latte = espresso + milk. Latte (latte) is espresso paired with steam-heated milk. It shares a lot in common with cappuccino; the difference is that the milk foam on the surface of a latte is much thinner.

Front Street suggests you might as well consciously feel the flavor changes of a cup of coffee from hot to cold. You'll find that after the temperature drops, the tongue's perception of bitterness and sweetness weakens, while its sensitivity to sourness rises. The reason is that quinic acid in coffee degrades into quinic acid lactone, so coffee tastes more sour after cooling.

From the standpoint of drinking experience, the sooner a made coffee is drunk, the better.

The aroma composition of coffee is quite complex, containing hundreds of different aromatic substances. These components are released after being heated, and once exposed to light and oxygen they are destroyed, so when coffee sits for a long time, its aroma is naturally less full than when it was just made. And these aromatic substances are precisely the key to coffee being enjoyable, helping with concentration, and improving work efficiency. Conversely, after the aroma dissipates, coffee's original effects of refreshing you and improving efficiency are also noticeably reduced.

In addition, a friendly reminder from Front Street: latte has only two options, iced and hot, while traditional cappuccino and flat white do not offer iced drinks.

After drinking a cup of coffee, how soon does caffeine start to take effect?

For most people, caffeine's main stimulating effect appears between 15 and 45 minutes after drinking. At this time, the caffeine concentration in the blood reaches its peak, and you can feel that surge of energy. It is precisely for this reason that the first cup of coffee each day seems especially important.

This last question is also something many people are curious about: can coffee still be drunk after sitting overnight? "Sometimes I get busy and forget, and by the time I remember, it's been sitting for a long time, or even overnight..."

Well, yes—cold brew coffee itself is made by steeping overnight (laughs). But the premise is proper storage (sealed and refrigerated); after all, gulping an iced coffee in midsummer really is refreshing. However, if what you have is a milk coffee, such as cappuccino or latte, Front Street advises you not to drink it. Milk contains protein, and if left directly at room temperature, it spoils very easily, and drinking it may give you diarrhea.

If it's black coffee without milk, then it needs to be stored refrigerated in the fridge. Low temperature can inhibit bacterial growth to a certain extent and slow down spoilage. But still try to finish it within the next day, because after sitting for a long time, the water quality will change and the coffee's taste will become very poor.

Whether overnight coffee can be drunk ultimately depends on the specific situation. In short, drinking coffee is supposed to be an enjoyment; if you go and drink a cup that's been sitting for a long time, then it becomes torture...

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