1. Grinding degree: Different grinding degrees will affect the contact area between coffee powder and water and the extraction time.
Ultra-fine grinding: The grinding degree required for espresso can extract the oil and rich flavor substances of coffee in a short time, but if the extraction time is not properly controlled, it is easy to over-extract, making the coffee bitter and burnt.
Medium grinding: Suitable for hand-brewed coffee, it allows water to flow through the coffee powder moderately and extract a balanced flavor. Grinding too coarsely or too finely will lead to insufficient or excessive extraction, affecting the taste of coffee.
Coarse grinding: Commonly used in French presses, it can avoid over-extraction and keep the coffee mellow taste. If the grinding is too fine, long-term soaking will make the coffee bitter.
2. Grinding uniformity: Uniform grinding is the basis for extracting balanced flavor coffee. If the coffee powder is not ground evenly, it will lead to uneven extraction.
Too coarse part: Insufficient contact with water, insufficient extraction, making the coffee taste bland and insufficient aroma.
Too fine part: It is easy to over-extract, produce bitterness and burnt taste, and destroy the overall flavor.
3. Grinding speed and heat generation:
High-speed grinding: may heat up the coffee beans, causing some flavor substances to volatilize, and may also cause the coffee to have a burnt smell, affecting the flavor.
Low-temperature grinding: helps to retain the aroma and flavor substances of the coffee beans, making the coffee flavor purer. Some high-end grinders reduce the impact of heat on flavor by using high-quality motors, heat dissipation design or low-temperature grinding technology.
4. Blade type:
Flat blade blade: The ground coffee powder particles are flaky, which can produce a large surface area, which is conducive to extraction, but there may be some uneven grinding, which is suitable for brewing methods such as espresso that require a higher extraction rate.
Conical blade blade: It can cut the coffee beans more evenly, produce less fine powder, and the shape of the coffee powder particles is closer to spherical, and the extraction is relatively more uniform. It is suitable for a variety of brewing methods and can better preserve the flavor and aroma of coffee.
Ghost tooth blade: The ground coffee powder is irregular in shape, with more edges and gaps, which can increase the contact area between coffee powder and water and make the extraction more complete. It is often used in hand brewed coffee to highlight the aroma and layering of coffee.
