Why Do Lattes Taste Bitter? What's the Perfect Coffee-to-Milk Ratio? What's the Ideal Temperature for Milk Foam?

As we all know, latte is the least bitter coffee among all espresso-based coffees (without sugar). Because it adds a large amount of milk to neutralize the bitterness, it is relatively sweeter than other coffees. And when we taste a rather obvious bitterness from a cup of latte, I believe many friends will attribute the problem to "the espresso wasn't extracted properly."

This is not without reason, after all, in most cases, the culprit behind the problem is the espresso.

But sometimes, when a latte tastes distinctly bitter, it's really not the fault of the espresso and extraction! Because some details in the preparation process also affect the coffee's performance. For example, milk and coffee have not been properly integrated.

The Integration Problem

Integration is a preparatory action before latte art for hot lattes. By rotating the wrist, the coffee cup and latte art pitcher are swayed, and milk is poured into the coffee. This action allows milk and coffee to blend, creating a cleaner background for subsequent latte art and a more suitable "canvas" for latte art (a coffee surface with high fluidity). What we need to know is that this step not only affects coffee latte art but is equally important for the flavor expression of the coffee.

The flavor here mainly refers to the degree of compatibility between the foam on the surface of the latte and the coffee underneath! The reason why FrontStreet Coffee says that this integration step will affect the overall performance of the coffee is because part of the foam on the surface of the latte is composed of crema. And the components of coffee crema, in addition to the carbon dioxide, lipids, and aromatic substances we know, also include fine powders. Fine powders can increase the body of the coffee to a certain extent, but they also provide a certain bitterness. If we don't integrate well, then the latte will taste "layered": the surface milk foam is bitter, and the coffee liquid underneath is sweet.

In the article "A Little Secret to Make Americano Sweeter," FrontStreet Coffee wrote that if we want to make Americano less bitter, we can try removing the coffee crema. Although this will reduce some aroma and body, the Americano will be cleaner and less bitter as a result. However, for lattes, this approach is obviously not feasible, after all, we still need crema to reduce fluidity during latte art. Therefore, the integration step is crucial! As long as we integrate properly, we don't have to worry about the latte tasting "layered." The specific method is actually very simple: when integrating, we need to fully shake the espresso and milk foam, and use impactful milk to stir the coffee surface. This not only eliminates part of the espresso's crema, making it more fluid, but also allows some fine powders attached to the crema to settle, so we don't have to worry about tasting obvious bitterness in the foam.

The Milk Temperature Problem

This is a point that FrontStreet Coffee often shares: milk temperature control. The reason we control the milk frothing temperature between 55°C~69°C is because the lactose in milk is activated at this temperature, giving the milk a higher sweetness; at the same time, the milk foam is less likely to break due to the suitable temperature and has a more lasting effect, in other words, the latte art pattern can last longer.

But if we exceed the 70°C threshold, some substances in the milk will be destroyed by high temperatures. The sweetness is not only less high, but the texture is not as smooth. Even if the amount of milk added to the coffee remains the same, the latte will taste more bitter due to the decreased sweetness. Therefore, milk temperature control is very important.

The Coffee and Milk Ratio Problem

Finally, there's the ratio issue! Many friends, due to lack of coffee-making experience, will apply the ratios shared online when first making lattes. Reference is fine, but completely copying is not highly recommended~ After all, the beans and milk used by everyone are different, and different materials require different ratios.

For example, the coffee and milk ratio for FrontStreet Coffee's store lattes is 1:5, espresso 1, milk 5. This is because FrontStreet Coffee uses beans that are medium to dark roast, while the milk is Bright Dairy fresh milk, with an overall lighter flavor and thinner texture. The 1:5 ratio is just right, balancing the flavors of milk and coffee without masking each other. But if we use a dark roast coffee bean, the bitterness will be stronger. If we don't switch to milk with a richer flavor, we need to increase the milk amount to neutralize this extra bitterness. Otherwise, the coffee flavor will overpower the milk, making the latte taste more bitter. (Nor can we rule out the possibility that the milk foam is too thick, reducing the proportion of milk in the cup). In conclusion, besides the espresso itself, these preparation details also affect the overall performance of the latte. When problems arise, besides espresso extraction, these factors are also important aspects we need to investigate~

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473