Sieve analysis is a method for determining particle size distribution by passing a ground-coffee sample through a stack of sieves with progressively smaller openings, then weighing the mass retained on each sieve. This is one of the oldest and easiest mechanical methods to implement for describing ground-coffee particle size.

What sieving tells you about ground coffee

Sieve results show what percentage of the sample's mass falls into each size range, based on each sieve layer's opening size. This is a mass-based approach, different from optical methods that measure individual particles, and this difference in principle should be kept in mind when comparing results between the two types of methods.

From retained mass to particle-size distribution

After weighing the mass retained on each sieve, you can calculate cumulative mass percentage by size and estimate markers such as median size. Accuracy depends on the number of sieves used, the size intervals between sieves, and the duration and intensity of shaking during the sieving process.

Reading the fine, medium, and coarse fractions

A complete sieve analysis should report the ratio across all three groups: fine particles passing through the smallest-opening sieves, medium particles making up most of the mass, and coarse particles remaining on the largest-opening sieve. Research on using ground-coffee particle size and distribution to model beverage properties emphasizes that the fine fraction, even though it's a small portion by mass, can still significantly affect the extraction process.

Advantages for internal quality control

Compared with optical laser-based devices, sieve analysis has a lower investment cost and a simpler operating procedure, making it suitable for a roasting facility to monitor grinder consistency over time without needing to invest in complex analytical equipment.

Factors that can distort sieve results

Sieve results can be skewed if shaking time isn't long enough for particles to fully separate through the sieve layers, if high sample moisture causes particles to clump together, or if the sample mass loaded is too large for the sieve set's capacity. Standardizing sieving time, sample mass, and environmental conditions is necessary for results to be comparable between measurements.

When a different PSD method is needed

When higher resolution is needed at the very fine end of the particle range, or when particle shape needs to be analyzed rather than just size, optical methods like laser diffraction are more suitable than sieve analysis. The choice of method should be based on the specific control goal, not on the assumption that a more expensive method is always the better choice for every situation.

Placing sieve data alongside brewing results

Particle-size-distribution data is only truly useful when cross-referenced against brewing results, such as flow rate, extraction time, or measured extraction efficiency. If a change in sieve distribution doesn't create a noticeable difference in brewing outcome, the priority given to controlling that indicator can be adjusted.

Practical conclusion

Sieve analysis is a practical and easy-to-implement tool for tracking grind particle-size distribution in internal quality control, especially for paying attention to the fine-particle ratio. The value of this method increases when sieve results are standardized in measurement procedure and regularly cross-referenced against actual brewing results.

References

• Using ground coffee particle size and distribution to remodel beverage properties (2023). European Food Research and Technology. DOI 10.1007/s00217-023-04210-3.
• Measuring the particle size distribution of coffee grounds using laser diffraction. Malvern Panalytical.
• Particle Size Distribution Model for Optimizing Coffee Grind Consistency (2025). Journal of Food Process Engineering, 48, e70129.
• Smrke, S., Eiermann, A. & Yeretzian, C. (2024). Scientific Reports, 14, 5612.