Why is one latte bitter and another balanced?

A latte is espresso plus steamed milk, so a bitter cup usually traces back to the coffee rather than the milk. Traditional blends with dark, cocoa-and-caramel roasting give a heavier, more bitter result, while lighter Ethiopian single-origin espresso tends toward milky sweetness and floral notes when paired with milk.

Milk is the second variable; the common fresh milks on the market differ in body, aroma and how strongly they mask the coffee. Extraction is the third, and the real work lies in setting the recipe rather than in distributing and tamping. Milk foam texture and pouring technique then shape how the layers meet in the cup.

Latte coffee seems simple—espresso plus steamed milk—but when it actually comes to drinking it, the results from different shops vary greatly. The key to whether a latte tastes good is not just the operating steps, but every link from coffee bean selection, milk quality, espresso extraction plan, to the fineness of the milk foam and the pouring technique—each one influences the final flavor presentation. Starting from sensory experience, this article breaks down the key points of making latte coffee one by one, and shares Front Street Coffee's practical experience when testing espresso and milk pairings, helping you determine where the problem lies in a cup of latte, and also enabling you to make a cup of latte with a full body and balanced flavor more consistently at home or in a shop.

However, when it comes to the most core sensory experience of a cup of latte, few people elaborate on it in detail. Yet this is precisely the foundation on which a beverage stands. If you have drunk lattes from a dozen or even dozens of coffee shops, you probably have this feeling: they are clearly all called lattes, and they all use a coffee machine to extract espresso and then add steamed milk, but the experience after drinking is just different.

The primary factor causing this difference lies in the different coffee beans selected. Nowadays, many coffee shops directly let customers choose which bean to use for their latte, so the finished flavors naturally differ. For example, a latte made with a traditional Mamba blend follows a route of rich roasted aroma with cocoa and caramel intertwining; while the Ethiopian SOE commonly used by many stores tends toward milky sweetness and floral notes when made into a latte—the two styles are completely different.

The second variable is milk. There are as many as seven or eight kinds of common fresh milk on the market alone. According to milk evaluations done by Front Street Coffee, some milk tastes watery and not full enough; some has a rich milky aroma and forms a good complement with coffee; some has too strong a milky flavor and instead overwhelms the coffee's own taste; and some is mellow on the palate, fragrant and smooth.

The third point lies in espresso extraction. The real difficulty is not the operational steps such as distributing and tamping the grounds, but the setting of the extraction plan. When many coffee shops debug espresso, the final step is often based on whether the resulting latte tastes good—because espresso performing well on its own does not mean it will necessarily taste good when made into a latte.

Milk coffee drinks like lattes and Americanos are currently the beverages with the largest output in coffee shops, so the correct extraction of espresso should be adjusted based on the final taste of these beverages. Limited by factors such as cup capacity, Front Street Coffee found during testing that the plan of extracting 40 grams of coffee liquid from 20 grams of grounds performed richly and with a full layering; but when used to make a latte, it was somewhat bitter and lacked mouthfeel. After adjusting the parameters to extracting 35 grams of coffee liquid from 20 grams of grounds, the resulting latte had a full mouthfeel, and the sweetness reminiscent of cream, chocolate, and brown sugar could all be presented.

The fourth point is the fineness of the milk foam after steaming, which directly affects the mouthfeel and the effect of blending with the coffee. Generally speaking, once you master the rhythm of the vortex formed by the steam wand, it becomes relatively easy to get the hang of it. If there is no need for latte art, the milk foam does not need to be steamed at all; you can directly heat the milk and use it, and the taste will not be compromised because of this.

The fifth point is the blending of milk and espresso. The common blending method is stirring clockwise: hold the coffee cup with your left hand and the milk pitcher with your right hand, starting to make circles from the 3 o'clock direction to the 6 o'clock direction. When making circles, you can let either the milk pitcher or the cup rotate, but be sure not to rotate both at the same time. If the rhythm is not controlled well and the milk and coffee collide with each other, what you end up with is a cup of latte full of large bubbles.

In the end, a delicious cup of latte is made step by step like this. Among them, Front Street Coffee believes the two most critical points are still the choice of coffee beans and the espresso extraction plan. After understanding these, the next time you drink a less-than-ideal latte, you will be able to roughly determine which link the problem lies in.

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