Espresso Coffee Bean Grind Size Standards: How to Determine Espresso Grind and Brew Ratio

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Many coffee enthusiasts have reported that after purchasing espresso blend coffee beans and grinding them for extraction, they cannot achieve proper crema. The resulting espresso generally lacks flavor and has a watery consistency. When this problem occurs, FrontStreet Coffee's baristas always recommend adjusting the grind size. This article will explain how to determine the proper grind size for espresso coffee.

Choose Freshly Roasted Espresso Beans

First, before adjusting the grind size, we need to select freshly roasted espresso beans.

Choose products from professional coffee roasters with clear indications of roast dates (not expiration dates or shelf life), reputable brands, and an emphasis on fresh roasting.

Additionally, quality coffee packaging bags typically feature a "one-way degassing valve" (a small button-like hole on the coffee bag) that allows coffee beans to release naturally produced carbon dioxide. Hold the one-way degassing valve to your nose and gently squeeze the coffee bag to smell the released gas. If it emits a charming, rich coffee aroma, the freshness is still good. Conversely, if it lacks rich aroma or even has a rancid oil smell, this indicates the coffee has long since deteriorated and lost its flavor, and should be avoided. Every bag of coffee beans sold by FrontStreet Coffee uses packaging with one-way degassing valves, ensuring that each bag reaches the purchaser in the freshest possible state.

Choose a Grinder Capable of Grinding Espresso

For commercial use, you can purchase espresso-style grinders. The biggest characteristic of espresso-style grinders is their extremely fine grinding capability, high speed, large burrs, and uniformity is a key indicator for judging whether a coffee grinder is good. Espresso-style grinders typically can achieve the extremely fine grind size that other grinders cannot reach. For home use to achieve espresso grind size, we should choose a flat burr grinder. FrontStreet Coffee currently uses a Fiorenzato 600N flat burr grinder for grinding espresso coffee.

Why Does FrontStreet Coffee Recommend Using Flat Burr Grinders?

Flat burr grinder working principle: Consists of upper and lower burrs, with the base fixed to the motor. When the motor starts, the upper and lower burrs rotate to create cutting action. When coffee particles fall from the center, the rotating lower burr pushes the coffee beans outward, advancing them into the teeth for grinding. The upper and lower burrs are positioned parallel, so coffee beans need the force from the rotating lower burr to push them into the burrs, thus the weight of coffee beans on top will affect the uniformity of beans entering the burrs, which in turn affects grinding uniformity. Additionally, the pushing action increases collision frequency between coffee beans, leading to a higher proportion of fine particles. This is why flat burr grinders typically have slightly less uniform particle size and more fine particles. This can increase coffee concentration and extraction rate in a short time, significantly enhancing coffee aroma quickly.

Flat burr grinder advantages: Clear positioning, product quality proportional to grinder level and burr diameter. Disadvantages: Slightly less uniform particle size, more fine particles, because flat burr grinder blades randomly cut coffee beans, which can easily lead to under-extraction or over-extraction during brewing. Additionally, flat burrs generate heat through friction, especially when working for extended periods, producing noticeable burnt and bitter flavors.

Grinding Principles of Coffee Grinders

When coffee beans enter the grinder, the blades inside crush them into powder. The smaller the distance between blades, the finer the coffee beans will be ground. The finer the ground particles, the more compact and dense they become, making it more difficult for water to pass through, thus significantly extending extraction time. Conversely, if the distance between blades increases, the ground particles become coarser, water passes through more easily, and extraction time becomes faster.

How Do We Determine the Right Grind Size for Our Espresso Machine?

FrontStreet Coffee starts by using the golden ratio and golden time for espresso extraction to establish parameters: a 1:2 ratio (20g of coffee grounds to extract 40ml of coffee liquid) with extraction time between 25 to 28 seconds, then adjusts the grind size through observation and tasting.

If the grind is too coarse, water will pass through the portafilter too quickly, resulting in large water flow, shallow extraction, pale crema color, and sharp acidic flavors, because extraction is incomplete - only extracting surface and easily extracted acidic substances.

If the grind is too fine, it will first clog the filter holes, with no water flow or thin water streams, dark crema color, surface over-extraction while inside remains under-extracted,表现为 sharp acidity due to insufficient sweetness, followed by burnt bitterness and off-flavors.

If you want to more rigorously test whether this espresso meets standard values, you can first calibrate the concentration tester, as most espresso concentrations fall between 7%-12%. Zero the standard with pure water. Then stir the extracted pour-over coffee and extract coffee liquid with a titration tube, place it in the coffee concentration tester, and press the measure button, taking multiple measurements until the value stabilizes.

FrontStreet Coffee's Espresso Extraction Parameters

FrontStreet Coffee currently uses a blend of sherry barrel-processed coffee beans and natural-processed Yirgachefe Red Cherry Project coffee beans for espresso. Sixty percent Honduras sherry barrel coffee beans provide flavor and body to this blend, while forty percent natural Yirgachefe coffee beans provide more aroma and acidity.

FrontStreet Coffee Espresso Extraction Parameters:

• Grinder: Fiorenzato 900N
• Grind Size: 1.6
• Pressure: 9 bar ± 2
• Temperature: 90.5~96°C
• Time: 20~30 s
• Dose: 20g (double shot espresso)
• Yield: 40ml extracted espresso

Flavor: Smooth mouthfeel, medium body, with distinct fruit acidity upon entry accompanied by light berry aroma, whiskey fragrance, rich chocolate flavor, and obvious aftertaste.

For more specialty coffee beans, please add FrontStreet Coffee's private WeChat: kaixinguoguo0925

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473