What Bloom strength is best for hard capsule vs softgel gelatin?

Beyond Biopharma | Pharmaceutical Gelatin FAQ

Short answer: The common starting point is that hard capsule shell gelatin is selected at a relatively high Bloom strength, typically around 200-280 g Bloom as an industry reference, so the shells are strong, rigid and fast setting, while softgel gelatin is usually a lower Bloom grade, roughly 100-180 g Bloom as a reference, paired with a higher viscosity so the ribbon film is elastic and seals well. These are working reference ranges only; the figure that governs your process is the one on the supplier certificate of analysis.

What Bloom strength measures

Bloom is the standard measure of gel strength for gelatin. A chilled, matured gel is pressed with a standard plunger and the force needed to depress it by a defined distance is reported in grams. The test is carried out on a solution of standard concentration under defined temperature and maturing conditions, so Bloom numbers from different suppliers are broadly comparable. In practical terms, a higher Bloom means a firmer gel at the same concentration, while a lower Bloom means a softer, more supple gel.

Hard capsules: why a higher Bloom grade is common

A hard capsule shell is made by dipping pins into a warm gelatin solution, drying the film, and stripping the finished shell from the pin. The shell must be rigid enough to survive filling, capping and transport, and the gel must set quickly so the line runs fast and the pins release cleanly. A higher Bloom gelatin gives that firmer set, which is why hard capsule gelatins are commonly supplied in the region of 200-280 g Bloom as a typical reference range, usually combined with a moderate-to-low viscosity for even, thin dipping films.

Softgels: lower Bloom plus high viscosity

A softgel shell is different: it is cast as a continuous warm ribbon on a cooled drum, and two ribbons are pressed together around a liquid fill in a rotary die. The shell film must stretch without tearing, deform around the fill, and seal completely under heat and pressure. A lower Bloom gelatin, commonly around 100-180 g Bloom as a typical reference range, produces a more supple film, and it is normally paired with a high viscosity so the ribbon keeps a uniform thickness and the seal is strong.

Typical reference values at a glance

The table shows typical reference ranges, not a specification. The actual target depends on the supplier grade, the machine and the formulation, so always confirm the values on the certificate of analysis.

Bloom never works alone

Gel strength and viscosity are linked, and neither is chosen in isolation. Machine speed, solution solids, plasticiser level, moisture and even the season all shift the practical target for a given line. A change in Bloom without a look at viscosity, or a change in viscosity without a look at Bloom, can change film behaviour in ways that only line trials will reveal. The reliable sequence is to agree a specification with the supplier, verify it on the COA, and then fine-tune on your own equipment.

Related reading

See also why softgel production needs high-viscosity gelatin and how to read a pharmaceutical gelatin specification (COA).