Theory of Gel Strength Testing
A Gel Strength Tester measures the mechanical resistance of a gel structure when subjected to controlled compression or penetration forces. Gel strength is a direct indicator of a material’s internal network integrity, elasticity, and resistance to deformation, which directly influences texture, stability, and performance in food, pharmaceutical, and cosmetic products. In quantitative terms, gel strength represents the relationship between applied force and deformation distance, commonly expressed as force (g or N) or force × distance (g·cm). A stronger gel exhibits higher resistance before rupture or penetration, while weaker gels deform or fail at lower force levels.
Theory of Bloom Testing
A Bloom Tester evaluates gel firmness using a standardized fixed deformation method, most commonly a 4 mm indentation performed with a 12.7 mm diameter cylindrical probe. The force required to reach this fixed depth is recorded as the Bloom value (Bloom g), which is an industry-recognized benchmark for gelatin and hydrocolloid quality. Bloom testing provides a repeatable, comparable metric for assessing gel consistency, batch uniformity, and compliance with industry specifications, especially in gelatin, confectionery, and surimi-based products.
Test Methods Used by QualiGST™ - 50
The Gel Strength & Bloom Tester – QualiGST™-50 supports multiple standardized testing modes to accommodate different material behaviors and application requirements:
Fixed Deformation Method
The probe compresses the gel to a predefined distance at a controlled speed while measuring the applied force.
This method is used for:
- Gel hardness evaluation
- Deformation resistance analysis
- Bloom g testing (4 mm indentation standard)
Fixed Load (Weight) Method
A constant force is applied to the gel, and the resulting deformation distance is measured.
This approach evaluates:
- Structural resilience under sustained stress
- Long-term gel stability characteristics
Peak (Rupture) Test Method
The probe continues compressing until gel rupture or penetration occurs, recording the maximum force value.
This method determines:
- Puncture resistance
- Elastic limit and rupture strength
- Gel Strength (g·cm) for structural integrity analysis
Gel Strength (G·cm) Measurement
Gel strength is calculated as:
Gel Strength = Force (g) × Distance (cm)
This value reflects both firmness and elasticity, providing a comprehensive mechanical profile of the gel material beyond simple hardness measurements.
Measurement Control and Accuracy
The QualiGST™-50 employs PLC-controlled motor drive systems with a precision ball-lead screw mechanism, ensuring stable test speeds and displacement accuracy up to ±0.01 mm. Controlled probe motion, repeatable loading conditions, and automatic return functions ensure consistent results across repeated tests and different operators.
