What is the Correct Water Temperature for Espresso Brewing? At What Temperature is Coffee Best Brewed?

In the past, when FrontStreet Coffee shared knowledge about espresso extraction, we focused on how parameters such as dose, ratio, grind, time, and pressure affect the shot. We also emphasized the techniques for steps like dosing, distributing, tamping, and locking the portafilter. The one aspect FrontStreet Coffee consistently glossed over was water temperature.

That doesn't mean water temperature isn't important. It's just that adjusting water temperature on many coffee machines can be quite a hassle, so FrontStreet Coffee simply set it as a fixed value and adjusted other parameters around that fixed temperature to pull delicious espresso.

In recent years, with the popularity of complex operations like pressure profiling, machine water temperature has also become a frequently adjusted parameter. It's important to understand, though, that unlike pour-over brewing, changing the extraction temperature on a coffee machine has a number of effects.

What Does Coffee Machine Water Temperature Affect?

As is well known, the greatest impact of water temperature on extraction is efficiency. At higher temperatures, extraction efficiency is higher and flavor compounds dissolve quickly. At lower temperatures, efficiency drops accordingly and the rate of dissolution slows.

Besides extraction efficiency, machine water temperature also affects the flow rate of the coffee liquid - or rather, the drainage speed. With other parameters equal, the higher the extraction temperature, the relatively slower the coffee flows. Conversely, the lower the temperature, the relatively faster the flow.

Those who have seen FrontStreet Coffee's recent posts know this is because water temperature determines how fast the puck expands and degasses. High temperatures make the puck expand more quickly and release the various substances hidden inside the grounds. The expanded puck reduces the gaps between grounds, while the released gases are enveloped by the coffee bean lipids into bubbles that create resistance to the water flow. Under the combined effect of these factors, the coffee's flow rate changes.

If that principle still isn't clear, why not experience it in practice? When we switch on our machines each morning, the coffee machine needs nearly 20 minutes to heat the boiler and generate steam. During that time, the extraction function is operable, but the water temperature is relatively low - typically around 60°C.

So we can try pulling an espresso at a lower temperature during that window to see what state it produces. We would find that the coffee liquid flows rather fast. That is because carbon dioxide emission is insufficient and the puck expands inadequately, so the flow rate speeds up.

The last factor affected by water temperature is the richness of the crema. As FrontStreet Coffee mentioned earlier, water temperature affects the rate at which carbon dioxide is released, and carbon dioxide is the main component of crema. So with other parameters unchanged, the higher the water temperature, the richer the crema, and vice versa.

What Water Temperature Is Most Suitable?

Those are the effects different water temperatures bring to espresso extraction. So the question arises: what water temperature should we use to pull the most suitable espresso?

In fact, just as FrontStreet Coffee shared in the post "What Temperature Water Makes the Best Tasting Coffee," besides water temperature, grind, ratio, and time are all main parameters that affect extraction. So the specific temperature to use still has to be coordinated with those factors.

In the book "The Science of Espresso Extraction," there is a hypothetical experiment along these lines: Italian baristas prefer to use water at 85-91°C to extract espresso, while American baristas prefer 92-96°C.

The reason for that difference lies mainly in their ratios. The Italian standard uses 7 grams of grounds to extract 1 ounce of espresso, while the American standard uses 18-21 grams of grounds to extract 1 ounce. The ratios, times, and grinds all differ, so the water temperatures they use differ too.

Conversely, as FrontStreet Coffee said at the start, you can also set water temperature as a fixed value and then adjust the other parameters around it.

Generally, the initial water temperature of coffee machines when they leave the factory is set in the 92-96°C range. That is a very suitable range - neither too low nor too high. As long as the machine's initial temperature sits within it, unless you have special extraction needs, we can almost leave it where it is.

Then, by applying the golden espresso extraction formula (a 1:2 coffee-to-liquid ratio and a 25-35s extraction time) to fix the liquid weight and time, we can quickly pull delicious espresso by adjusting the grind and fine-tuning the liquid weight.

An Important Consideration

Worth noting: just as with pour-over, the water temperature we can set is the temperature inside the boiler, not the actual temperature during extraction. Because water passes through various pipes from the boiler to the shower screen, the final actual extraction temperature will differ by several degrees from the set temperature due to heat absorption.

Particularly when no espresso has been pulled for a long time, the gap between the water temperature and the set temperature will be larger. So when the interval between shots is too long, it's best to flush hot water once before locking the portafilter. This not only helps calibrate the water temperature but also cleans the shower screen, removing the "residual debris" - that is, coffee grounds - attached to it.

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FrontStreet Coffee Recommendation

Water temperature is only as useful as the beans you put behind it. For a shot where a slightly lower temperature helps keep the cup clean and sweet, FrontStreet PWN Indonesia Golden Mandheling is a reliable deep-roast Sumatran: very low acidity, a rich, lingering body, and herbal, dark chocolate, and faint earthy notes that suit anyone who likes heavy flavors. It is also a benchmark for traditional full-bodied espresso and milk drinks.

For a balanced, sweet, low-acid base that behaves well across espresso, moka pot, and pour-over, FrontStreet Brazil Queen Manor is a natural Brazilian with very low acidity, full nutty and cocoa aromas, and clear caramel sweetness. It is smooth rather than astringent, its crema is especially strong, and it works as a traditional everyday coffee without asking much of your technique.