What is the standard ratio for Italian latte? Why homemade milk coffee often tastes bitter and bland?

I wonder if everyone remembers when they first had a latte. Perhaps many people have long forgotten, but FrontStreet Coffee still remembers it vividly. The first sight of the delicate latte art was eye-catching, a small sip revealed the slight sweetness and bitterness from the crema, and by the second sip, the previous strong bitterness transformed into richness and smoothness, paired with the sweet freshness of hot milk, presenting a perfect balance in the mouth. After finishing, there was still a hint of cream chocolate-like aftertaste.

As the famous Western saying goes, "There are a thousand Hamlets in a thousand people's eyes," and the same is true for coffee. When it comes to delicious latte, perhaps everyone has their own standard answer in mind. Some friends like it for its generous portion, others are fond of its rich flavor and balance, while still others are fascinated by the exquisite latte art.

On the contrary, for a bad-tasting latte, people's answers are surprisingly similar—either the coffee is too bitter to drink, or the taste is too weak (watery) with no appeal, or it has both qualities—both bitter and weak. What's going on here?

Latte Coffee Formula

FrontStreet Coffee's standard store configuration uses their own Sunflower Warm Sun blend, which adopts medium-dark roast. The requirement for making latte is to have flavors of vanilla, cream chocolate, and caramel cookies.

Based on this, we first use the common formula for espresso: a coffee-to-liquid ratio of 1:2, getting about 2g of coffee liquid from 1g of coffee grounds, with a time between 25-35 seconds, then apply this to actual extraction. For example, FrontStreet Coffee uses a double portafilter with 20g of coffee grounds to extract 40g of espresso, with the time controlled between 27-33 seconds, and without any abnormalities during the entire extraction process (channeling, splashing, unstable flow rate).

If making a hot latte, FrontStreet Coffee follows a 1:5.5 ratio, pouring 220ml of fresh milk into the milk pitcher and frothing it to 55-65°C, with 0.3-0.5cm of foam, then evenly mixing it with the espresso in a ceramic cup and creating a neat pattern.

When making an iced latte, we use three ice cubes as a base, controlling the coffee-to-milk ratio at 1:5, first pouring 200g of fresh milk, then drizzling 40g of espresso on top to preserve the beautiful layered effect.

From FrontStreet Coffee's experience, as long as the coffee beans and milk pairing are chosen appropriately, and the espresso extraction is stably controlled while grasping the right milk ratio, making a delicious latte is actually quite simple. In other words, if a latte doesn't taste right, the problem must lie in the aforementioned points. Below, let's solve them one by one.

First, Why is Latte Too Bitter?

As everyone knows, without adding sugar, latte is the least bitter among all specialty coffees because it's mixed with a large amount of milk, and the coffee flavor is often not prominent. When we do taste obvious bitterness, it indicates that the problem is likely with the espresso—either the coffee beans are roasted too dark, or the extraction parameters are not correct.

Regarding the former, unless you're buying extremely dark-roasted coffee beans that are black and oozing oil, in order to preserve more of the coffee beans' own flavor, most common espresso formulas on the market actually use medium-dark to dark roasts, at most just coming out of the second crack. Espressos made from these types of products typically have rich crema, slight acidity, and moderate coffee bitterness, which can form a compatible taste when neutralized with milk, without highlighting any particular aspect.

Generally speaking, the "main culprit" that makes latte bitter usually lies in the espresso extraction, with the most common issues being too slow flow rate (extraction time exceeding 35 seconds according to the above formula), channeling, or liquid column splattering leading to over-extraction.

A customer once gave feedback to FrontStreet Coffee, saying that their homemade lattes usually tasted quite good, but suddenly one day the taste became particularly bitter and not aromatic. The coffee beans were within their freshness period, extraction parameters and ratios were the same as usual, they just didn't know where the problem was. After some inquiry, it was discovered that the used coffee puck had already perforated, indicating channeling during extraction, possibly due to clumped coffee grounds, which led to over-extraction and bitterness. In this case, the corresponding solution is to adjust the grind to be coarser, or to use external force to break up the clumped coffee grounds.

What to Do When Latte Tastes Too Watery or Too Weak?

From a barista's perspective, the richness of a latte is determined by two aspects: milk and espresso. For lattes, milk, which accounts for the largest proportion, is naturally a key factor. If you want the coffee to be rich and aromatic, we recommend prioritizing whole fresh milk because compared to room-temperature milk or skim milk, whole milk contains higher milk fat content, the foam layer after frothing is denser and more stable, and it provides a fuller texture for the coffee.

Actually, besides milk quality issues, under-extraction of espresso can also make lattes watery or weak. This situation usually occurs with SOE (Single Origin Espresso). FrontStreet Coffee once used a lightly roasted Guaxupé 8.0 to make SOE lattes. Although the milk ratio was reduced, the resulting taste was still extremely bland, like a hot milk with a hint of citrus and caramel aroma. Obviously, this was due to insufficient extraction caused by too light a roast.

So when we use single-origin coffee beans featuring fruity aromas to make large lattes, it's best to choose the corresponding SOE version, which makes it less likely to "go wrong."

Why Would a Latte Be Both Bitter and Weak?

This situation is usually the opposite of the SOE cases mentioned earlier. It's often because the coffee beans are roasted too dark, and the espresso's overall taste presents a heavy and burnt flavor profile, with the latter part of the extraction often dominated by bitterness, woody notes, and unpleasant flavors. If a higher extraction ratio is used, the espresso is very likely to become over-extracted.

For example, some people like to extract 40g of coffee liquid from 18g of coffee grounds. At this point, the coffee-to-liquid ratio falls approximately at 1:2.22. This not only makes the coffee bitter and astringent, but the increased liquid weight also means more water content, so the coffee's concentration decreases, resulting in a latte that's naturally both bitter and weak.

If you feel that your homemade latte also has this contradictory taste, then you might as well try reducing the espresso extraction amount by a little, such as reducing 5g of liquid weight to increase concentration. This both avoids over-extraction and makes the latte's texture richer.

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

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