Psyllium for Capsule Filling: Mesh, Flow, and Grade Guide
Application.

Psyllium husk is one of the most commonly encapsulated dietary fibres, used in laxative and digestive health supplements sold in gelatin and vegetarian (HPMC) capsules. The key challenge in capsule filling is flowability — psyllium husk is fibrous and hygroscopic, which means it can clump and bridge in filling equipment hoppers, causing inconsistent fill weights. Mesh selection and moisture control are the two primary variables that determine filling performance.

For standard capsule filling equipment (dosator or tamping pin type), 40–60 mesh whole husk is the preferred specification. At this mesh, particles are large enough to flow without bridging but small enough to pack uniformly in the capsule body. Below 40 mesh (coarser), husk may not pack efficiently, leading to low fill weights. Above 60 mesh (finer), the powder becomes more hygroscopic and tends to clump. For powder-in-capsule formats using husk powder rather than whole husk, 60–80 mesh is standard.

Moisture control is critical: husk above 10% moisture will clump in the hopper and cause fill weight variation. Suppliers should provide a COA with moisture tested close to the shipment date. We test moisture at dispatch and can provide moisture-controlled packing (sealed HDPE liner with desiccant) on request for sensitive shipments. Share your capsule size, target fill weight, and filling equipment type — we will recommend the grade, mesh, and moisture specification that matches your production setup.