Espresso Extraction Standards: The Espresso-to-Milk Ratio in Latte Coffee

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Latte is a familiar beverage to everyone - this milk-based coffee can be considered a standard in every coffee shop. However, making a delicious latte is no easy task. The flavor of latte coffee varies with different coffee beans, varying richness of fresh milk, and different extraction parameters. In this article, FrontStreet Coffee will discuss how to extract espresso and how much espresso should be added to a latte.

How many milliliters are in a standard espresso shot?

The internationally accepted technical standard is as follows: using approximately 7 grams of freshly ground coffee powder, extracted with water at around 92°C under approximately 9 Bar of pressure for 20-30 seconds to yield about 20-30ml of coffee, which should be covered with a layer of crema. With the development of specialty coffee, some new coffee theories have been disclosed, and numerous independent coffee shops have blossomed, each with slightly different espresso extraction methods. According to FrontStreet Coffee's standard production, an espresso is produced with 2 shots (1 portion of espresso) as the standard, using 19g of coffee powder to extract 38g of espresso liquid at a 1:2 ratio, with a time of 28 seconds.

However, these are just reference values! Beneath the foam of espresso are tiny oil droplets that have dissolved sugars, acids, proteins, and caffeine. Suspended on the foam surface are also bubbles and solid solutions. The wear degree of the grinder blades will also gradually change with humidity and storage time, so the grind setting needs to be adjusted daily to ensure stable espresso flavor. Therefore, whether an espresso extraction of how many milliliters is qualified actually mainly depends on the powder-to-water ratio and the flavor performance of the extracted coffee.

How to understand espresso extraction parameters?

Dose: The amount of powder is generally determined by the size of the portafilter basket. It is not recommended to use significantly less or significantly more powder than the basket's capacity. The amount of powder affects the density of the coffee puck. Under the same tamping pressure, too little powder will be relatively sparse, leading to faster flow rates and under-extraction. Conversely, the density will be more compact, with slower flow rates or even difficulty in extracting coffee liquid. For example, the portafilter basket used by FrontStreet Coffee is suitable for holding 19-20g of coffee powder, and more or less than this range is not ideal.

Ratio: This refers to the ratio of coffee powder amount to coffee liquid amount, generally between 1:1.5 and 1:2.5, with 1:2 being more common, such as extracting 34g of coffee liquid from 17g of coffee powder. The ratio is affected by two factors: one is the powder amount, and the other is the water amount. Too low a ratio will make the coffee taste very rich and thick, with bitterness from over-extraction. Conversely, too high a ratio will result in a thin and bland taste with sharp acidity from under-extraction.

Time: This refers to the entire extraction time from locking in the portafilter and pressing the extraction button to completion. The factors affecting extraction time include grind size and ratio. The ratio is easier to understand - a higher ratio means more water is needed for extraction, naturally taking longer. Grind size affects the coarseness of the coffee powder, which directly impacts the density of the coffee puck. The finer the coffee powder, the denser the puck after tamping, making it difficult for water to pass through, lengthening the time and easily leading to over-extraction.

Flow rate: This is the speed at which coffee liquid flows down. The ultimate goal of our extraction parameters is actually a flow rate result. Our espresso should start dripping the first drop of coffee liquid at the fifth second after pressing the extraction button, extracting coffee evenly, such as reaching exactly 34g of coffee liquid at 30s. The speed of the flow rate directly reflects whether the grind size and ratio are appropriate.

Pressure: Averages around 9 bar, which is determined by the performance of the coffee machine. Insufficient pressure leads to low extraction efficiency, while excessive pressure easily causes over-extraction.

Water temperature: Generally between 90 to 94 degrees Celsius. Water temperature that is too high easily causes over-extraction, making the coffee taste bitter. Water temperature that is too low easily causes under-extraction, resulting in sharp acidity in the coffee taste.

What factors affect espresso flavor?

Coffee beans: The factor of coffee beans has the most important impact on espresso flavor. If you have tasted espresso (or Americano) from multiple coffee shops, you can almost clearly distinguish the differences in taste. The most direct reason is that each coffee shop uses different espresso beans. For example, FrontStreet Coffee's specialty blend coffee beans focus on balanced nutty and cocoa flavors in espresso; the Sunflower Warm Sun blend coffee beans display sherry wine and vanilla chocolate flavors.

Pressure: Generally determined by the performance of the coffee machine, typically averaging around 9 bar. Some high-end coffee machines have variable pressure functions, providing different pressures for extraction. When extracting espresso, water quickly passes through the coffee powder under pressure for extraction. Generally, with insufficient pressure, coffee is prone to under-extraction, appearing sharp, thin, and lacking in body; while excessive pressure easily over-extracts coffee substances, resulting in coffee that is too rich, thick, and bitter.

Coffee grind size: Grinding espresso beans typically uses flat burrs with large diameters, which has the advantage of efficiently grinding fine coffee powder quickly. Espresso machines are very sensitive to feedback on grind size - what might be a 0.1 scale difference on the grinder can result in a 2-3 second difference in espresso extraction time. Therefore, appropriate grinding has a significant impact on espresso portafilter baskets. The finer the grind, the more easily extraction substances can be released, making the coffee more prone to bitterness and burnt flavors; conversely, sharp acidity and thin flavors are more likely to appear.

Powder-to-liquid ratio: This is the ratio of coffee powder to coffee liquid. FrontStreet Coffee's espresso powder-to-liquid ratio is 1:2, which is also an important parameter for coffee extraction. If this ratio is reduced, flavor expression may be incomplete; increasing the ratio may cause the overall coffee texture to become thin.

Extraction time: Once we've determined the powder-to-liquid ratio, the time required to extract a certain amount of coffee liquid will also affect the coffee's flavor. The reasonable extraction time range for espresso is generally between 20-30 seconds. Slower flow rates mean longer times, with coffee flavors becoming richer; faster flow rates mean shorter times, with coffee flavors becoming thinner.

Extraction water temperature: This refers to the temperature at which water from the brew head presses through the coffee puck. Generally, new espresso machines come with options for brew head water temperature selection. Like pour-over coffee, the higher the water temperature in espresso extraction, the stronger the extraction efficiency, and flavor substances are more easily extracted, and vice versa. When extracting espresso, temperatures rarely fall below 90°C, typically preset between 90-93°C. The reason some home coffee machines have poor endurance (inability to guarantee continuous cup quality) is because their boilers are small and cannot maintain brewing temperature for large volumes of water. Therefore, pay attention to the temperature gauge before brewing.

Different espresso blend coffee beans/single-origin coffee beans have different extraction parameters. Everyone can extract at a 1:2 powder-to-liquid ratio first, then adjust parameters based on the espresso's flavor performance. When adjusting espresso extraction parameters, pressure and water temperature are machine settings that should not be adjusted as much as possible. As baristas, the parameters we adjust daily are one of: grind size, ratio, or extraction time! Note, you can only choose one parameter to adjust! Only choose one parameter to adjust! Only choose one parameter to adjust! (Important things need to be said three times~)

How many milliliters of espresso should be added to a latte?

Different brands of fresh milk have varying richness levels and lactose content, so we need to make the espresso accommodate the milk. This is generally achieved by adjusting the coffee powder amount and liquid amount (powder-to-water ratio) to adjust the base espresso parameters for milk coffee, as well as adjusting the milk-to-coffee ratio to help balance the milk coffee flavor. Latte is primarily milk-based, more like a milk with coffee flavor, so the coffee flavor doesn't need to be too prominent.

FrontStreet Coffee recommends a coffee-to-milk ratio of 1:6.5 for making lattes, extracting 40g of espresso from 20g of coffee powder with 260ml of milk. Everyone can adjust the latte flavor based on this parameter and then create latte parameters suitable for their own beans and milk.

Important Notice :

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