Can Single-Origin Coffee Beans Be Used for Espresso? What's the Difference Between Pour-Over Beans and Blend Beans? How Does Roast Level Affect the Taste?

During FrontStreet Coffee's monthly limited events, many friends stock up on large quantities of single-origin pour-over beans to use as espresso beans! This might be because they're tired of the rich and mellow deep-roasted coffee, or it could be to experience more diverse coffee flavors. In any case, the reason some friends buy large quantities of single-origin beans is specifically for making espresso!

Single-origin coffee beans are primarily medium-light to light roasted, so they differ significantly in roast degree from the deep-roasted beans originally used for espresso. This has led to some friends making less-than-ideal espresso. Coincidentally, today is another FrontStreet Coffee's bean event, so I'm taking this opportunity to share what you need to pay attention to when using pour-over beans to make espresso coffee.

I. Extraction Parameters

Making a good cup of espresso with single-origin coffee beans is no simple task! Many friends apply the extraction parameters for deep-roasted espresso beans to light-roasted single-origin beans, resulting in espresso with sharp acidity and thin mouthfeel - under-extracted and lacking concentration. Since espresso serves as the base for all specialty coffees, if it doesn't taste good, let alone the specialty coffees made from it.

This is precisely what needs the most attention: deep-roasted and light-roasted beans cannot share the same extraction parameters. The root cause of this problem is the differences brought by varying roast degrees.

Deep-roasted beans are characterized by high expansion rate, low density, and high brittleness! Light-roasted beans, because their roasting time is relatively shorter, have characteristics completely opposite to deep-roasted beans! The density of beans determines how easily their flavor compounds can be extracted. Under the same extraction efficiency, lower density beans will more easily release flavor compounds, while higher density beans do the opposite!

The brittleness of beans determines the uniformity of ground coffee particles! When beans have higher brittleness, they can be easily broken, producing more fine particles beyond the target particle size during grinding. Additionally, compared to light-roasted beans, the ground particles will be finer. This will obstruct water flow during extraction, giving hot water more extraction time; while less brittle beans, being harder to break, won't produce excessive ultra-fine particles, and the particles are more uniform. Consequently, hot water will have more gaps to flow through, significantly reducing residence time and thus lowering extraction efficiency. Combined, these factors lead to light-roasted beans using deep-roast parameters failing to produce good espresso due to insufficient extraction efficiency.

Therefore, if we want to make good espresso using light-roasted pour-over single-origin beans, we cannot apply the extraction parameters of deep-roasted beans to light-roasted beans. Light-roasted single-origin beans need more extraction efficiency, so what we need to do is improve the overall extraction efficiency by adjusting extraction parameters. Among extraction parameters, the grind size of coffee beans is the optimal choice!

By grinding finer, we can make the coffee particle size smaller, reducing the gaps between coffee particles. Hot water will thus have more extraction time, and the extracted coffee will naturally have a more appropriate extraction rate. Similarly, FrontStreet Coffee suggests using a formula approach to quickly find the suitable grind size for the current coffee beans.

For example, FrontStreet Coffee uses 20g of light-roasted beans, extracting 40ml of coffee liquid in 30-35 seconds. If the current 20g of coffee beans extracts 40ml of coffee liquid in about 10-15 seconds, we need to adjust the grind 2-3 notches finer, because the time parameter gap is large and requires more significant adjustment. The extraction time here is just a reference, because light-roasted beans have high density, and even if the total extraction time is longer, it's not easy to extract negative substances, so decisions should be made based on specific circumstances. Finally, you just need to taste and make fine adjustments to address any shortcomings!

II. Coffee Proportion

The proportion here refers to the "coffee flavor" performance in specialty coffees! Because the flavor of light-roasted coffee is not as prominent as deep-roasted coffee, even if you extract espresso with suitable flavor, it's not recommended to use the original method to make specialty coffees. This is because the espresso flavor can easily be over-diluted or masked by other strongly flavored ingredients like milk. Here, we have two adjustment directions to choose from!

The first is to increase the dose, which means increasing the concentration of espresso. By increasing concentration, we can ensure that the espresso has richer flavor compounds in the same liquid volume, making it less likely to be masked by other strongly flavored ingredients (extraction parameters need to be adjusted)! And because light-roasted beans have much smaller volume than deep-roasted beans, this means that a portafilter set for deep-roasted bean doses can accommodate more light-roasted coffee than the recommended amount! For example, a portafilter with a recommended dose of 20g can accommodate 22g of light-roasted coffee (or even more), so we don't need to worry about using too much coffee.

The second is to reduce the total proportion of other ingredients (water, milk, etc.). By reducing the proportion of other ingredients, the espresso flavor won't be as easily masked. For example, if a latte made with deep-roasted beans originally had a 1:5 ratio - 40ml of coffee liquid with 200ml of milk - then a latte made with light-roasted beans could have a 1:4 ratio - 40ml of coffee liquid with 160ml of milk. The reduction in milk increases the coffee proportion, so the flavor won't be diluted too much.

Warm Tips for Making Milk Coffee with Light-Roasted Single-Origin Beans

Another thing to note when making milk coffee is that light-roasted beans retain a lot of acidity, and acid combined with milk can be quite jarring. So if we want to make a good cup of milk coffee, it's best to increase the extraction rate of light-roasted espresso to extract more bitter compounds and reduce the proportion of acidic compounds. This way, the overall acidity of the espresso decreases, and the resulting milk coffee will be more enjoyable to drink~~

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