A manufacturer recently asked us why they suddenly could only fill their glucosamine capsules to 80% of their weight from previous production runs when the only change was the production lot from the raw material supplier. With the material being in spec they wanted to know: what is the significance of bulk density, tap density, and particle size when encapsulating?

All supplement capsule manufacturers face the same challenges of sourcing raw materials that flow freely while also having the proper density to fit the required dosage into the capsule. Tap density is a good indicator of how a product will respond to the encapsulation process but is not commonly specified by raw material producers. Bulk density however is usually included on a material spec and therefore is used to determine the suitability for encapsulation. Generally speaking, the bulk density and tap density are proportional, and so this works as an adequate indicator on how a product will perform in capsule making – until it doesn’t.

For one thing particle size matters – a larger particle size will generally increase tap density – but so do both particle size distribution and particle shape as well. And these can all vary significantly while the material is still within spec.

The solution? Choose a manufacturer and supplier with decades of experience producing the product from raw material to finished dose and who understands the unique challenges of each dosage form. In this case TSI Group offers a capsule grade glucosamine specifically processed to ensure consistent filling from lot to lot, every time.

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