In the pharmaceutical and nutraceutical industries, ensuring the bloom strength of soft gelatin capsules is critical for product integrity, consumer safety, and manufacturing consistency. Bloom strength, often overlooked outside laboratory settings, is a key measure of gel firmness, directly influencing capsule durability, shelf life, and dissolution behavior. This article discusses what bloom strength is, how it’s measured using a bloom tester, and why reliable testing solutions like the CHT-01 Bloom Tester from Cell Instruments Co., Ltd. are essential for quality control and compliance.

What Is Bloom Strength?

Bloom strength refers to the firmness or gel strength of a gelatin sample, specifically the force (in grams) required by a standard plunger to depress the surface of a gel by 4 mm at a controlled temperature (commonly 10°C). Originally developed for gelatin used in desserts, it has become a fundamental parameter in the formulation and production of soft gelatin capsules. Higher bloom values indicate a firmer gel, affecting capsule shell strength, elasticity, and drug release rates.

For softgel manufacturers, monitoring bloom strength is essential for:

• Ensuring capsule integrity during filling, transport, and storage

• Controlling dissolution characteristics in the gastrointestinal tract

• Maintaining consistent production quality batch after batch

Why the Bloom Strength of Soft Gelatin Capsule Matters

Soft gelatin capsules are widely used for encapsulating oils, vitamins, and active pharmaceutical ingredients (APIs). Their outer shell—typically composed of gelatin, water, and plasticizers—must maintain a delicate balance of flexibility and strength. If the bloom strength is too low, the capsule may be too soft, leading to deformation or leakage. Too high, and it may become brittle and prone to cracking.

Controlling bloom strength is directly linked to capsule performance, patient compliance, and product stability. Therefore, regular testing is an integral part of quality assurance in manufacturing environments.

How a Bloom Tester Evaluates Gel Strength

A bloom tester is a precision instrument that quantifies gel strength using force-deformation testing. In a typical test, a probe or plunger descends at a defined speed into the gelatin sample. The force required to depress the surface by 4 mm is recorded as the bloom value.

Modern testers go beyond simple measurements. For instance, Cell Instruments’ CHT-01 Bloom Tester offers advanced capabilities tailored for capsule and softgel testing, including:

• Multiple test modes: Measure force at fixed distances, peak rupture force, or deformation under constant force

• PLC-controlled automation and a 7-inch touchscreen interface for easy operation

• Precision ball screw drive and variable test speeds for high accuracy

• Customizable jigs and fixtures to accommodate different capsule sizes and configurations

• Data output via screen, printer, or RS232 interface for streamlined reporting

With a displacement accuracy of 0.01 mm and force accuracy of 0.5% F.S., the CHT-01 ensures repeatable and traceable results that align with industry standards.

Applications in Pharmaceutical Quality Control

Testing the bloom strength of soft gelatin capsule is a routine part of pharmaceutical QC protocols. It is often performed:

• During raw material acceptance to qualify incoming gelatin batches

• In R&D when developing new capsule formulations or improving bioavailability

• Throughout production to ensure batch-to-batch consistency and compliance with pharmacopeial standards like USP or EU guidelines

Manufacturers who invest in high-precision testers like the CHT-01 Bloom Tester can reduce material waste, avoid costly recalls, and increase consumer trust in their products.

Choosing the Right Bloom Tester for Softgel Applications

When selecting a bloom tester, professionals should consider factors such as:

• Testing range and sensitivity

• User interface and data management options

• Compatibility with various capsule types and gelatin samples

• Ease of maintenance and durability

The CHT-01 by Cell Instruments stands out due to its multi-functional testing modes, customizable fixtures, and high-speed precision mechanics. It is designed not only for standard gelatin testing but also optimized for the soft gelatin capsule production environment, making it a trusted choice for R&D labs and high-throughput manufacturing lines alike.

Conclusion

In softgel production, ensuring proper bloom strength of soft gelatin capsules is more than a technical requirement—it’s a cornerstone of quality assurance. Accurate and consistent testing using advanced instruments like Cell Instruments’ CHT-01 Bloom Tester helps manufacturers meet regulatory requirements, optimize production, and deliver reliable, effective products to the market. For laboratories and factories seeking dependable, customizable testing solutions, Cell Instruments provides the technology and support to elevate your testing capabilities.