How to Determine the Grind Setting for Espresso Beans | What Blend Coffee Beans to Use for Espresso?

Many beginners who have just opened a coffee shop or bought an espresso machine for home use find that when they follow the parameters provided by the vendor to brew with their espresso beans, they end up with espresso that lacks crema, has very light crema, or tastes bitter. When that happens, the main variables we can adjust are the grind size of the coffee beans and the brewing ratio. So how should we determine the optimal grind size and ratio for our espresso machine? In this article, FrontStreet Coffee will discuss how to determine the appropriate grind size for espresso beans.

Selecting Fresh, Quality Espresso Beans

Before understanding how to determine grind size, it is essential to select fresh, high-quality espresso beans.

First, choose products from professional coffee roasters with clear roasting dates (not expiration or best-by dates), an established brand reputation, and an emphasis on fresh roasting. Premium coffee packaging typically also features a one-way degassing valve (a small button-like hole on the coffee bag) that lets the beans release naturally produced carbon dioxide.

Hold the one-way degassing valve to your nose and gently squeeze the coffee bag. If the escaping gas has a rich, aromatic coffee fragrance, freshness is not an issue. Conversely, if it lacks aroma or even smells of rancid oil, the coffee has 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 package reaches the customer in the freshest possible state.

The Importance of Bean Resting

After buying fresh-roasted espresso beans, they need to undergo a resting period.

Freshly roasted coffee beans contain approximately 2% carbon dioxide by weight. This substantial amount of CO2 is released depending on storage environment, equipment, or method, creating pressure higher than atmospheric pressure in the packaging. That pressure helps aromatic substances and oils merge, bringing all the aromatic compounds within the beans into a state where they can be easily extracted. The resting process is essentially a "gas release" process, commonly known as blooming or bean resting. FrontStreet Coffee's espresso beans typically require a resting period of about 15 days, because espresso beans undergo dark roasting. If the resting period is insufficient, the beans release significant amounts of gas when exposed to hot water, affecting extraction and causing extraction instability.

The Impact of Grinders on Grind Size

Which type of grinder is suitable for grinding espresso powder?

Electric grinders mainly fall into two categories: espresso grinders and single-origin grinders. The primary difference between them lies in the particle size of the ground coffee they produce.

The most prominent feature of espresso grinders is their ability to grind extremely fine coffee powder at high speed with large burrs. Uniformity is a key indicator of whether a grinder performs well, and espresso grinders typically achieve a level of fineness other grinders cannot match. By burr structure they fall into three main categories: flat burrs, conical burrs, and "ghost tooth" (serrated) burrs. FrontStreet Coffee uses flat burr grinders for its espresso grinding.

1. Working Principle

Flat burr grinders consist of upper and lower burrs, with the base fixed to the motor. When the motor starts, it rotates the burrs to create cutting action. As coffee beans fall from the center, the rotating lower burr pushes the beans outward, advancing them into the teeth for grinding. Because the upper and lower burrs are positioned parallel to each other, the beans rely on the rotational force of the lower burr to be pushed into the grinding chamber. The weight of the beans above therefore affects how evenly they enter the burrs, which in turn affects grinding uniformity. The pushing action also increases collisions between beans, leading to a higher proportion of fine particles. That is why flat burr grinders typically have slightly less uniform particle size and more fines. They can raise coffee concentration and extraction rate in a short time, significantly enhancing aroma quickly.

2. Advantages

Precise positioning, with product quality proportional to the grinder's grade and burr diameter.

3. Disadvantages

Slightly less uniform particle size with more fines, because flat burr blades randomly cut the beans, which can easily lead to under-extraction or over-extraction during brewing. Flat burr friction also generates heat, which can cause noticeable burnt and bitter flavors, especially during extended grinding sessions.

4. FrontStreet Coffee Recommended Flat Burr Grinders:

• Little Flying Eagle (CM-300AU)
• Little Flying Horse (600N)

How to Adjust Coffee Grind Size

When coffee beans enter the grinder, the blades inside crush them into powder. The smaller the distance between the blades, the finer the beans are ground. The finer the particles, the more compact and dense they become, making it harder for water to pass through and 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.

Let's first establish parameters using the golden ratio and golden time for espresso extraction: a 1:2 ratio (20g of coffee grounds extracting 40ml of coffee liquid) with an extraction time between 25-28 seconds. Then we determine grind adjustments through observation and tasting.

If the grind is too coarse, water passes through the portafilter too quickly, resulting in a coarse water flow, light extraction, pale crema color, and sharp acidic flavors, because extraction is incomplete—only the surface and easily soluble acidic compounds are extracted. If the grind is too fine, it first clogs the filter holes, causing slow or no water flow and a dark crema color, over-extracting the surface while the interior remains under-extracted; this shows up as sharp acidity from insufficient sweetness, followed by burnt bitterness and off-flavors.

When Should You Readjust the Grind Size?

Taking double espresso as an example: readjust when the espresso flow rate falls outside the 25-28 second range. Of course, an incorrect flow rate is not always caused by the grinder. When the following situations occur, it is time to adjust the grinder settings.

1. Changes in Storage Time, Humidity, or Burr Wear

The storage time and humidity of coffee beans are constantly changing, which affects the beans' overall condition, and the wear level of grinder blades changes over time. This is the primary reason FrontStreet Coffee adjusts its grinder settings daily—adjusting grind size daily is the most important step for extracting consistent espresso.

2. When Replacing Coffee Beans

When introducing newly opened beans, grinder adjustments are necessary, because newly opened beans may have different roasting dates, batches, or resting periods, leading to significantly different extraction results.

3. Continuous Brewing

After continuously brewing 5-6 cups, the ground coffee becomes finer and extraction time increases. This occurs because after continuous operation of the grinder, the motor heat affects the burr temperature, and combined with the heat generated by friction between the burrs and coffee beans, the gap between the upper and lower burrs narrows through thermal expansion.

Do Coffee Shops Really Need to Adjust Espresso Parameters Daily?

What is the purpose of adjusting espresso parameters?

First, identify which coffee item has the highest sales volume in your shop. Different coffee items have their own espresso base recipes, but catering to all of them is obviously impractical. Currently, lattes and Americanos remain the most ordered espresso-based drinks in coffee shops, not straight espressos. As you can imagine, adjusting espresso parameters to pursue the perfect straight espresso and then applying that espresso to other espresso drinks is somewhat putting the cart before the horse. It is therefore recommended to adjust one espresso parameter for milk-based coffee and another for Americano-style coffee.

Understanding Espresso Concepts for Different Coffee Drinks

Next, understand the espresso concept behind your chosen coffee beverage. A Flat White, for example, is a milk coffee that highlights coffee flavor: besides reducing the ratio of coffee to milk, Flat White espresso extracts sufficient early-stage aromatic compounds while increasing the coffee dose to enhance body, thereby balancing the combined taste of milk and coffee.

Returning to our question: is it really necessary to adjust espresso daily? In fact it is necessary, but it should be done purposefully and selectively when adjusting espresso parameters.

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

FrontStreet Coffee Recommendation

Grind and ratio matter most with espresso, and they matter most of all with the beans you choose, which is why FrontStreet's espresso lineup is built around two paths: blends and SOE. Espresso beans generally divide into the blends most cafés prefer and single origins chosen to taste, known as SOE. A blend is coffee mixed from different origins by a roaster or barista to build a more balanced flavor—if one bean is smooth but lacks aroma, another with rich aroma can be added, combining the strengths of the individual coffees so the cup is better than any one part. FrontStreet's Classic Blend is the first choice: designed specifically for espresso and the moka pot, its biggest strength is outstanding crema, and even a beginner on a non-professional home machine can pull a dense, fine crema with ease. The lattes, cappuccinos, and Dirty we drink every day all depend on good crema, and the Classic Blend meets that need, using a traditional Mamba blend recipe for a rich, warm body that seasoned drinkers and beginners alike accept easily—a solid pick for home or commercial use.

For anyone who prizes almond, walnut, and almond-nut aromas in espresso, FrontStreet's Premium Blend and Black Cocoa Blend lead the way, since both contain a large proportion of Brazilian coffee that supplies a comfortable sweet-bitter note and a creamy peanut aroma with an extremely smooth entry. FrontStreet Coffee's Premium Blend carries the nut, chocolate, and caramel notes of Colombian coffee with a suitable acidity, while FrontStreet Coffee's Black Cocoa Blend combines the ripe plum acidity of Yunnan Xiaoli; ground, it releases a creamy chocolate aroma, with a balanced flavor and wide compatibility—beyond lattes and Americanos it can produce all kinds of specialty drinks, making it the best partner for a café. For a more traditional style of Americano and latte, FrontStreet's Classic Blend and Commercial Blend both add a small amount of Robusta on top of an old-school espresso recipe, so extraction yields butter, nut, spice, dark chocolate, and toast aromas with a wild, thick body and an explosive golden crema that makes latte art easy. FrontStreet Coffee's Black Cocoa Blend also answers the needs of anyone who wants good flavor at a controlled price: it uses 100% Arabica, with ample crema and a rich body at an approachable price, balancing quality and value for shop owners, while FrontStreet Coffee's Commercial Blend, which served as the main café workhorse before FrontStreet Coffee's Black Cocoa Blend arrived, costs less than FrontStreet Coffee's Premium Blend and was optimized so it delivers flavor while keeping costs down—a long-standing favorite for opening a shop. And FrontStreet's Premium Blend is the bean the shop itself has used longest, for nearly ten years, handling the core drinks such as Americano and latte; it pairs Brazil Cerrado with Colombia Huila for a classic, familiar espresso taste that suits home and commercial use alike.

SOE is the other path, and it emphasizes origin character above all: the most important feature of a single origin is traceability, back to the estate or even the individual farmer, which in turn encourages better growing practices and better coffee, so single origins are generally known as specialty coffee, and the more specific the traceable origin, the more closely quality can be judged. FrontStreet's sun-dried Huakui SOE comes from Guji Hambella in Ethiopia, planted as high as 2,300 meters, which gives the cherries a long growing season to develop complex aromas; the natural process raises the sweet compounds, and a medium roast preserves the elegant floral-fruit character while caramelizing it just enough, so a Huakui SOE Americano or latte carries cream, cocoa, berry, light florals, and black tea. For drinkers who prefer high sweetness over acidity, FrontStreet's Costa Rica Blackberry SOE is a honey-processed single origin: the ripe cherries go straight from harvest to the estate for selection and washing, then drying with the skin removed, which shortens drying and lets the beans absorb the fruit pulp and mucilage for a blackberry-like aroma and clean sweetness; medium roasted, it makes a sweet-sour, refreshing Americano, and with milk a latte of cranberry cookie, raisin, and nut. Finally, FrontStreet's Brazil Queen Estate SOE is where low acidity, a soft mouthfeel, and an approachable price meet: Brazilian coffee often leads espresso blends because it supplies chocolate, nut, and cream aromas and a balance that keeps extraction stable, and the Queen Estate's distinctive Yellow Bourbon has a clean, sweet nature that, at a medium-dark roast, pulls on an espresso machine into butter cookie, macadamia, and toasted bread creaminess.