Purity and Mesh Are Two Separate Measurements
Purity describes how much of the material is actually husk. Psyllium husk is the thin outer coat milled off the seed of Plantago ovata. However carefully it is separated, some seed fragments, fine dust and other light matter stay with it. A 98% grade means that at least 98% of the weight is husk and no more than 2% is everything else.
Mesh describes particle size. It applies to husk that has been ground into powder, and the number refers to the sieve it passes through. A higher mesh number means a finer powder.
The two are independent. You can buy 99% purity husk as whole flakes or as 100 mesh powder, and you can buy 95% purity in either form too. A complete specification states both.
Purity Grades at a Glance
| Grade | What it looks like | Typical uses |
|---|---|---|
| 85% | Darker, with visible brown seed fragments and more fine dust | Animal and pet nutrition, industrial applications |
| 95% | Light beige with occasional darker specks | Food manufacturing, bakery, general fibre products |
| 98% | Pale and uniform, very few specks | Dietary supplements, health foods, branded fibre products |
| 99% | The lightest and cleanest grade, close to speck-free | Pharmaceutical products, capsules, premium supplements |
The dark specks buyers notice in lower grades are mostly seed fragments. They are not a sign of contamination in themselves, but they do tell you roughly where a lot sits on the purity scale before any test result arrives. Put a spoonful on white paper in good light and the difference between a 95% and a 99% lot is usually visible.
What Purity Does Not Tell You
Purity is a measure of cleaning, and nothing more. A 99% lot can still fail a specification on other parameters, so treat these as separate lines:
- Swell volume. How much water the husk takes up, stated in ml per gram. Higher purity generally swells more, but the figure depends on the crop and the processing, so specify a minimum and the test method.
- Microbial limits. Purity has no bearing on yeast, mould or pathogen counts. If your limits are tight, the husk may need a kill step. Our sterilization guide covers the options.
- Heavy metals and pesticide residues. These come from the field, not the mill, and are tested per lot.
- Moisture. Set a maximum, because it affects shelf life and weight.
Whole Husk or Powder
Whole husk is the intact flake as it comes off the mill. Powder is the same husk ground and sieved to a set mesh. Neither is the better product; they suit different uses.
| Whole husk | Powder | |
|---|---|---|
| Form | Light flakes | Ground to a stated mesh |
| In water | Hydrates more slowly, with a coarser texture | Hydrates quickly and gels more evenly |
| Common uses | Loose fibre products taken with water, traditional isabgol | Capsules, drink mixes, bakery and gluten-free formulations |
| Shipping | Bulkier, so fewer kilograms fit in a container | Denser, so freight per kilogram is lower |
One practical consequence: a specification written for powder cannot be applied to whole husk. Particle size, bulk density and the way swell volume behaves all differ, and a sample of one tells you little about the other. Confirm the form before a sample is prepared, not after it arrives.
Mesh Sizes for Powder
| Mesh | Texture | Typical uses |
|---|---|---|
| 40 | Coarse powder | General food use; the usual standard grade |
| 60 | Medium | Drink mixes, cereal and bakery blends |
| 80 | Fine | Gluten-free baking, smoother drink mixes |
| 100 | Very fine | Capsules and tablets, formulations that need a smooth mouthfeel |
Finer powder gels faster and feels smoother, which matters in a capsule line or a baking mix. It also thickens more quickly in a glass, which some drink products want and others do not. If you are developing a new product, ask for small samples at two mesh sizes and test them in your own process.
The "95%" That Means Two Things
Here is the confusion that causes the most trouble. Powder specifications often carry a line such as "95% through 80 mesh". That is a particle-size statement: 95% of the powder passes an 80 mesh sieve. It says nothing about purity.
So "psyllium husk powder 95%" on a quotation can mean 95% purity, or it can mean 95% passing a given mesh at some other purity. Always write the two as separate lines:
- Purity: minimum 98%
- Particle size: minimum 95% passing 80 mesh
If a supplier's spec sheet gives you only one percentage, ask which of the two it refers to before you compare prices.
How Grade and Mesh Affect Price
- Higher purity costs more. Each step up needs additional cleaning passes, and each pass removes some good husk along with the impurities. The yield loss is what you pay for.
- Finer mesh costs more. Grinding to 80 or 100 mesh takes more milling and more sieving than 40 mesh.
- Whole husk changes the freight. Because it is bulkier, the freight cost per kilogram is higher than for powder, even where the product price is similar.
- The raw seed price moves everything. Purity and mesh set the difference between grades. The season sets the level. Our crop calendar explains what drives it.
The cheapest sensible approach is to buy the grade your application needs and no higher. A bakery blend rarely needs 99%. A capsule product usually should not be built on 95%.
What to Write in Your Specification
- Form: whole husk or powder.
- Purity: minimum percentage.
- Particle size, for powder: mesh and the percentage passing.
- Swell volume: minimum in ml/g, with the test method.
- Moisture: maximum.
- Microbial limits, heavy metals and pesticide residues, with methods.
- Appearance, including the colour you expect.
If you already have a specification, send it to us and we will quote against it. If you do not, tell us the application and the destination market and we will suggest a grade and mesh to start from.
Frequently Asked Questions
1. What does 99% purity mean for psyllium husk?
It means at least 99% of the material by weight is husk, with no more than 1% seed fragments, dust and other matter. It is the cleanest commonly traded grade and is used mainly for pharmaceutical products, capsules and premium supplements.
2. What is the difference between psyllium husk purity and mesh size?
Purity measures how much of the material is husk. Mesh measures the particle size of husk that has been ground into powder. They are independent, so a full specification states both.
3. Which psyllium husk purity grade should I buy?
Buy the grade your application needs. Around 85% is used for animal nutrition and industrial purposes, 95% for food and bakery, 98% for dietary supplements, and 99% for pharmaceutical products and capsules.
4. What mesh size is best for psyllium husk powder?
40 mesh is the usual standard for general food use. 60 and 80 mesh suit drink mixes and gluten-free baking, and 100 mesh is common for capsules, tablets and formulations that need a smooth texture.
5. What does "95% through 80 mesh" mean?
It is a particle-size statement meaning 95% of the powder passes through an 80 mesh sieve. It does not describe purity, which should be stated as a separate line in the specification.