Overview
ISO 4150:2011 - "Green coffee or raw coffee - Size analysis - Manual and machine sieving" specifies a routine laboratory method to determine the size distribution of green (raw) coffee using manual and machine sieving with laboratory test sieves. The standard describes required apparatus, sampling, sieving procedures, result calculation and reporting, and includes normative annexes for sieve characteristics and machine verification. Key practical parameters include a 300 g test portion, 3-minute sieving, and balance precision to 0.1 g.
Key topics and requirements
- Scope and principle: Separate a laboratory sample into size fractions by sieving; report results as percentage mass fractions.
- Sampling: Take a 300 g laboratory sample prepared per ISO 4072.
- Apparatus:
- Balance accurate to 0.1 g.
- Nest of test sieves (550–1 000 cm² surface area), with either round holes (Annex A) or slotted apertures (Annex B).
- Compliant lids, receivers and a sieving machine (adjustable timer 0–3 min).
- Procedure:
- Assemble sieves in descending aperture size; discard overly large apertures.
- Manual sieving: agitate the sieve nest for 3 min at ~110–130 cycles/min (defined displacement), with guidance for slotted sieves.
- Machine sieving: run for 3 min; verify machine yields results equivalent to manual sieving (Annex D).
- Weigh fractions to 0.1 g and calculate percentage retained on each sieve.
- Results and reporting:
- Express mass fraction retained per sieve as percentage of test portion; total should be 100 ± 0.5 %.
- Test report must reference ISO 4150:2011 and include sample ID, sieve type, method, results, foreign matter, and any non-standard operating details.
- Precision:
- Repeatability and reproducibility limits are provided (statistically derived in Annex C); interlaboratory data are included.
Applications and users
- Coffee producers and exporters use ISO 4150:2011 for lot grading and quality control to classify bean size distribution.
- Quality laboratories and roasters apply the method to monitor incoming green coffee and to document conformity for purchasing/specifications.
- Inspection bodies and trade labs use the standard for reproducible, comparable size analysis in trade disputes and specification verification.
- The standard supports consistent coffee grading, quality assurance, procurement decisions, and traceable test reporting.
Related standards
Keywords: ISO 4150:2011, green coffee, size analysis, manual sieving, machine sieving, test sieves, coffee grading, laboratory method, sieve sizes, precision.
