Particle size analysis of solid condiments and seasonings is a critical quality control test that measures the particle size distribution of powdered and granulated food ingredients such as spices, bouillon powders, salt, sugar, and compound seasoning blends. Accurate particle size characterization directly affects product flowability, dissolution rate, blending uniformity, caking resistance, and overall consumer acceptance. This article explains the testing standards, analytical methods, measurable parameters, and practical applications used by accredited third-party laboratories and food manufacturers worldwide.
Technical Overview
Solid condiments and seasonings—including spice powders, salt, sugar, monosodium glutamate, and compound seasoning blends—are manufactured and sold in particulate form, typically ranging from coarse granules of several millimeters to fine powders below 50 micrometers. The particle size distribution (PSD) of these products is one of the most influential physical properties governing end-use performance. It determines how quickly a soup base dissolves, how uniformly a snack coating adheres, how reliably a powder flows through dosing equipment, and how prone a product is to caking during storage.
Particle size analysis is performed using standardized sieving and instrumental techniques, principally mechanical sieve analysis and laser diffraction. These methods are governed by recognized international and national standards, including ISO 13320 (laser diffraction methods), ISO 9276 (representation of particle size analysis results), ISO 3310-1 (technical requirements for test sieves), ASTM E11 (specification for woven wire test sieve cloth), GB/T 19077 (the Chinese adoption of the laser diffraction standard), and GB/T 15445 (representation of particle size distribution results). Food safety requirements for compound seasonings are further addressed under GB 31644, which reinforces the need for consistent physical quality in finished products.
Manufacturers, importers, and brand owners routinely submit samples to accredited third-party laboratories to verify conformity with internal specifications, customer requirements, and trade specifications. Results are reported as cumulative and differential size distributions, characteristic diameters (D10, D50, D90), or sieve pass-through and retention percentages at specified mesh sizes.
Testing Samples
Single-Ingredient Powders
Common single-ingredient samples include refined table salt, white sugar and icing sugar, monosodium glutamate (MSG), maltodextrin, glucose syrups in powder form, and native or modified starches. These materials usually exhibit relatively narrow, well-defined size distributions controlled by crystallization, grinding, or granulation processes, making them well suited to both sieve and laser diffraction analysis.
Spice and Herb Powders
This category covers ground chili, paprika, black and white pepper, turmeric, cumin, coriander, cinnamon, garlic powder, onion powder, and blended spice mixes. Because spices are milled from natural raw materials of varying hardness and oil content, their size distributions tend to be broader and may contain fibrous oversize particles. Sieve residue testing at defined mesh sizes is frequently specified in purchase contracts.
Compound Seasoning Powders and Granules
Compound seasonings—such as chicken or beef bouillon powder, soup bases, hot pot seasoning mixes, snack coating seasonings, and marinade blends—combine salts, sugars, amino acids, hydrolyzed vegetable proteins, flavor powders, and anti-caking agents. These multi-component systems can segregate during handling, so representative sampling and whole-distribution measurement are essential. Hygroscopic components such as MSG and salt require controlled humidity conditions during testing.
Dehydrated Vegetable and Flavor Granules
Instant noodle seasoning sachets, dehydrated vegetable granules (chive, carrot, cabbage), and agglomerated flavor particles are analyzed to confirm granule integrity after drying and packaging. Oversize and undersize fractions are both controlled, as fines reduce visual appeal while coarse particles slow rehydration.
Testing Items
Depending on the product specification and selected method, particle size analysis of solid condiments typically reports the following parameters:
- Particle size distribution (PSD), presented as cumulative undersize curves and frequency (density) distributions
- Characteristic diameters: D10, D50 (median size), D90, and where required D97 or Dmax
- Span or distribution width, calculated as (D90 minus D10) divided by D50
- Sieve pass-through percentage at specified mesh openings, for example 60, 80, 100, or 120 mesh
- Sieve residue (oversize) percentage on specified sieves, often limited for spice powders and coating seasonings
- Uniformity coefficient and distribution modality (single-peak versus multi-peak behavior)
- Supporting flow indicators such as bulk density, tapped density, Hausner ratio, and Carr index, which correlate strongly with particle size
- Optional specific surface area for flavor release and dissolution studies
Testing Methods
Mechanical Dry Sieve Analysis
A nested stack of calibrated wire-mesh sieves conforming to ISO 3310-1, ASTM E11, or GB/T 6003.1 is loaded with a weighed sample and shaken on a mechanical or electromagnetic sieve shaker for a defined period. Each retained fraction is weighed, and the mass-based distribution is calculated. Dry sieving is the reference method for most free-flowing seasoning powders and directly matches the mesh-based language commonly used in commercial specifications.
Air-Jet Sieving
For fine, cohesive, or lightly agglomerated powders such as icing sugar or fine spice flours, air-jet sieving de-agglomerates the sample on a single sieve with pulsed air jets while a vacuum draws fines through the mesh. It improves reproducibility compared with conventional dry shaking for particles below approximately 75 micrometers.
Laser Diffraction Particle Size Analysis
Laser diffraction performed in accordance with ISO 13320 or GB/T 19077 measures the angular scattering pattern of dispersed particles and converts it into a volume-based size distribution using Mie or Fraunhofer theory. Dry powder dispersion with compressed air is preferred for hygroscopic and water-soluble seasonings such as bouillon powders; wet dispersion may be used with appropriate non-aqueous carriers or pre-saturated solutions to prevent dissolution of soluble components. The method delivers rapid, repeatable D-values and full distribution curves from submicron to millimeter sizes.
Dynamic Image Analysis
Dynamic image analysis captures two-dimensional projections of particles in motion, providing both size and shape information. It is valuable for granulated seasonings and dehydrated vegetable pieces where elongation, aspect ratio, or fiber content influences functionality and where sieving alone cannot distinguish shape-driven differences.
Data Representation and Reporting
Results are presented following ISO 9276 and GB/T 15445, including tabulated size classes, cumulative curves, characteristic diameters, and measurement conditions such as dispersion pressure, refractive index assumptions, obscuration range, and sieve calibration status. Reports issued by accredited third-party laboratories also state the measurement uncertainty where applicable.
Applications
Particle size analysis supports the solid seasoning industry across the entire product lifecycle:
- Incoming material inspection of salt, sugar, MSG, starches, and ground spices against supplier specifications
- Milling and grinding process control, including hammer mill and roller mill settings and grinding aid evaluation
- Granulation, agglomeration, and drying optimization for soup bases and instant beverage powders
- Blend homogeneity and segregation studies for multi-component compound seasonings
- Dissolution, dispersion, and rehydration performance verification for instant noodle and bouillon products
- Anti-caking formulation development and storage stability or shelf-life assessment
- Packaging line compatibility, including hopper flow, auger dosing accuracy, and dust control
- Export documentation, customer specification conformity, and dispute resolution supported by independent laboratory data
FAQ
How do mesh numbers relate to micrometers? Mesh numbers count the openings per linear inch of sieve cloth, so higher mesh numbers correspond to finer particles. As common reference points, 60 mesh corresponds to about 250 micrometers, 100 mesh to about 150 micrometers, and 200 mesh to about 75 micrometers. Certified sieves should be verified against ISO 3310-1, ASTM E11, or GB/T 6003.1 requirements.
Which method is best for hygroscopic bouillon powders?Laser diffraction with dry dispersion is generally preferred because it avoids dissolving water-soluble components and minimizes moisture uptake during measurement. If wet dispersion is required, a saturated solution of the sample in the carrier liquid or a non-aqueous dispersant can be used. Air-jet sieving is a practical alternative when a single mesh specification must be verified.
What do D10, D50, and D90 mean?These are the diameters at which 10, 50, and 90 percent of the sample (by volume for laser diffraction, by mass for sieving) is smaller. D50 is the median size, while the spread between D10 and D90 relative to D50—the span—indicates distribution breadth and uniformity.
How much sample is required?Sieve analysis typically requires 50 to 200 grams of representative sample depending on particle coarseness, while laser diffraction and image analysis need only a few grams. Proper sampling following statistically sound procedures is more important than sample quantity, since compound seasonings can segregate during transport.
How often should particle size be tested?Most manufacturers test each production batch or every defined sampling interval, with additional testing after raw material changes, mill maintenance, or process modifications. Routine verification by an accredited third-party laboratory is recommended for benchmarking in-house results and for export certification purposes.
Can test results from sieving and laser diffraction be compared directly?Both describe the same material but on different bases—mass for sieving and volume for laser diffraction—and use different physical principles, so small systematic differences are expected. Correlation studies should be established so that consistent conclusions can be drawn when both techniques are used across a product portfolio.