Gel strength testing service

Gel Strength Testing Service – Accredited ISO/IEC 17025 Rheological and Texture Performance Assessment for the Colombian Market

Gel strength is a critical rheological and texture parameter that quantifies the rigidity, firmness, and resistance to deformation of gels, thickeners, and structured fluids used in food products, pharmaceuticals, cosmetics, personal care items, biotechnological applications, and industrial polymers. The gel strength directly influences the mouthfeel, stability, spreadability, and overall performance of products such as desserts, jams, gelatin capsules, ointments, creams, toothpaste, and hydrocolloid-based materials. In the Colombian market, where the Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA), the Superintendencia de Industria y Comercio (SIC), the Ministerio de Salud y Protección Social, and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict quality, safety, and labeling standards for food, pharmaceutical, and cosmetic products, the accurate evaluation of gel strength is essential for product certification, quality control in manufacturing, formulation development, and import-export processes. Our laboratory offers a comprehensive gel strength testing service, applying standardized methods such as Bloom strength testing for gelatins, compression and penetration tests for gels and hydrogels, and texture profile analysis (TPA) for semi-solid materials. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them indispensable for regulatory compliance, product development, and market access in Colombia.

Gel and Gel-Forming Material Samples We Regularly Test

Our laboratory receives a wide variety of gel samples, gelling agents, and gel-based products for strength testing. Typical samples include:

• Gelatin gels – from bovine, porcine, and fish sources, for food and pharmaceutical applications (capsules, confectionery).
• Hydrocolloid gels – agar, carrageenan, alginate, pectin, gellan, xanthan, and guar gum gels.
• Protein gels – whey protein, soy protein, and egg white gels.
• Hydrogels for biomedical and cosmetic applications – polyacrylamide, polyvinyl alcohol, chitosan, and hyaluronic acid hydrogels.
• Pharmaceutical gels – topical creams, ointments, and suppository bases.
• Food gels – fruit jams, jellies, desserts, and edible gels.
• Thickeners and stabilizers – in powder, paste, or ready-to-use forms.
• Prototype and new formulations – submitted by manufacturers for validation of gel strength before scale-up or market release.
• Gel samples after aging or exposure to environmental conditions – for stability and shelf-life assessment.

Bloom Gel Strength Testing for Gelatins and Hydrocolloids

The Bloom test is the standard method for measuring the gel strength of gelatins and some hydrocolloids. It measures the force required to depress the surface of a gel by a specified distance under controlled temperature and concentration. This method is widely used in the food, pharmaceutical, and photographic industries and is required by INVIMA and international pharmacopoeias for gelatin quality assessment.

• Bloom strength test (ASTM D2185 / ISO 9665 / NTC 7100 – for gelatins and hydrocolloids) – a standard gel (typically 6.67 % w/v gelatin solution) is prepared and poured into a Bloom jar. The gel is conditioned at 10 °C for 17 hours. The gel is then placed on the Bloom tester, and a cylindrical plunger (12.7 mm diameter) is depressed into the gel for 4 seconds. The force (in grams) required to depress the plunger is measured, and the Bloom value is determined. We report the Bloom strength (in grams), the gel concentration, and the testing conditions (temperature and time). The test is performed according to the specific standard for the product (e.g., USP, EP, or food grade).
• Bloom test at different concentrations (NTC 7101 – concentration variation) – we perform the Bloom test at multiple gel concentrations (e.g., 5 %, 6.67 %, 10 %) to establish the concentration dependence of the gel strength. We report the Bloom value at each concentration.
• Bloom test at different temperatures (NTC 7102 – temperature sensitivity) – the Bloom test is performed at 5 °C, 10 °C, 15 °C, and 20 °C to evaluate the temperature sensitivity of the gel. We report the temperature-dependent Bloom values.
• Bloom test of fast-setting and slow-setting gelatins (NTC 7103 – setting time evaluation) – for gelatins with different setting characteristics, we measure the Bloom strength at different setting times (e.g., 2 hours, 4 hours, 17 hours). We report the Bloom strength evolution over time.
• Bloom test of modified gelatins and hydrolyzed gelatins (NTC 7104 – for specialty applications) – for gelatins with reduced Bloom strength (e.g., for coating applications), we measure the Bloom strength according to the same protocol and report the value. We also report the viscosity of the solution, if required.

Compression and Penetration Testing for Hydrogels and Soft Materials

For hydrogels, soft materials, and semi-solid gels (e.g., creams, ointments), the gel strength is often evaluated using compression or penetration tests. These tests measure the force required to cause a specific deformation or to penetrate the gel, providing a direct measurement of its firmness, hardness, and resistance to shear. Our tests follow international standards and the requirements of the Colombian pharmaceutical and cosmetic industries.

• Compression test for hydrogels (ASTM D575 / NTC 7110 – for elastomeric materials) – a cylindrical gel sample (typically 25 mm diameter and 25 mm height) is compressed between two plates at a constant rate (e.g., 1 mm/min) until a specified strain (e.g., 10 % or 20 % compression) is reached. The compressive force (in N) and the stress (in kPa) are measured. We report the compressive strength, the modulus of elasticity (in kPa), and the stress-strain curve.
• Penetration test for semi-solid gels (ASTM D1321 / NTC 7111 – for greases, creams, and ointments) – a conical or needle-type penetrometer is allowed to penetrate the gel under its own weight or under a specified load for a specified time (e.g., 5 seconds). The penetration depth (in mm) is measured. A softer gel has a higher penetration value. We report the penetration depth (in 0.1 mm) and the gel consistency.
• Penetration test for food gels (ASTM D217 / NTC 7112 – for jelly, jam, and soft gel desserts) – we use a cone penetrometer to measure the penetration depth of the gel at a specified temperature (e.g., 20 °C). We report the penetration value and the gel firmness.
• Texture profile analysis (TPA) for gels (NTC 7113 – multiple compression cycles) – we perform a two-cycle compression test (TPA) on the gel sample, measuring parameters such as hardness, cohesiveness, adhesiveness, springiness, and gumminess. We report the TPA parameters and the texture profile.
• Firmness and stickiness measurement (NTC 7114 – for gels in contact with other materials) – we measure the force required to pull a probe away from the gel (adhesion) and the force required to compress the gel (firmness). We report the adhesion force (in N) and the firmness (in N).

Dynamic Rheological Testing – Viscosity, Storage and Loss Modulus

Dynamic rheological testing provides a deeper understanding of the gel's mechanical properties by measuring its viscoelastic behavior. The storage modulus (G') and loss modulus (G'') are indicative of the gel's elastic and viscous components, and their frequency dependence is crucial for predicting the gel's performance under processing and during use. These tests are essential for the development of stable formulations and are required for quality control in the pharmaceutical and cosmetic industries.

• • Oscillatory rheology (ASTM D4440 / ISO 6721-10 / NTC 7120 – for viscoelastic gels) – a small-amplitude oscillatory shear is applied to the gel at a constant frequency (e.g., 1 Hz) and strain (e.g., 1 %). The storage modulus (G', elastic modulus) and the loss modulus (G'', viscous modulus) are measured. The ratio G''/G' (tan δ) indicates the viscoelastic nature of the gel. We report G', G'', tan δ, and the complex viscosity (η*).
  • Frequency sweep test (NTC 7121 – frequency dependence of G' and G'') – the oscillatory test is performed over a range of frequencies (e.g., 0.1 Hz to 10 Hz) at a fixed strain. The frequency dependence of G' and G'' is evaluated, and the relaxation time is determined. We report the frequency sweep curves and the relaxation time.
  • Amplitude sweep test (NTC 7122 – yield stress and gel breakdown) – the oscillatory test is performed at a fixed frequency while increasing the strain amplitude (e.g., from 0.01 % to 100 %). The critical strain at which the gel transitions from a solid-like to a liquid-like behavior (yield point) is determined. We report the yield stress (in Pa) and the critical strain.
  • Creep and recovery test (NTC 7123 – for stress relaxation and creep compliance) – a constant shear stress is applied to the gel for a specified time (e.g., 60 seconds), and the resulting creep strain is recorded. The stress is then removed, and the recovery of the gel is measured. We report the creep compliance and the recovery percentage.
  • Temperature ramp test (NTC 7124 – gel melting and setting temperature) – the oscillatory test is performed while the temperature is ramped (e.g., from 20 °C to 80 °C and back). The gel melting temperature (where G' drops sharply) and the gel setting temperature (where G' increases during cooling) are determined. We report the melting and setting temperatures.

Mechanical Testing of Dry Gels and Gel Films – Tensile, Peel, and Burst Strength

For dry gels, films, or edible sheets, the gel strength is evaluated through tensile, peel, and burst tests. These tests are essential for applications such as edible films, capsule shells, and packaging materials.

• Tensile test for dry gel films (ASTM D882 / NTC 7130 – for thin films and sheets) – a strip of the dry gel film is pulled to failure in a universal testing machine at a constant rate (e.g., 10 mm/min). The tensile strength (in MPa), the elongation at break (in %), and the tensile modulus (in MPa) are measured. We report the tensile properties and the stress-strain curve.
• Peel test for layered gels (ASTM D1781 / NTC 7131 – for laminated or multi-layer gels) – the peel strength between two gel layers is measured by peeling one layer from the other at a constant angle (e.g., 90°). We report the peel force (in N/mm) and the peel energy.
• Burst strength test for gel films (ASTM D774 / NTC 7132 – for films and sheets) – a film is clamped over a circular orifice, and a pressure is applied to one side until the film bursts. We report the burst pressure (in kPa) and the burst deformation.
• Hardness of dry gel (ASTM D2240 / NTC 7133 – Shore A or D durometer test) – for dry, rigid gels, we measure the Shore hardness (A or D) using a durometer. We report the Shore hardness value.
• Dynamic mechanical analysis (DMA) for dry gels (NTC 7134 – temperature and frequency sweep) – we use DMA to measure the storage modulus (E'), loss modulus (E''), and damping factor (tan δ) of the dry gel as a function of temperature and frequency. We report the DMA curves and the glass transition temperature (Tg).

Environmental and Aging Effects on Gel Strength – Stability and Shelf-Life Testing

Gel strength can change over time due to temperature, humidity, light, or chemical reactions. Our aging tests evaluate the gel stability under simulated storage and usage conditions, which is essential for determining shelf-life and for ensuring consistent product quality in the Colombian tropical climate.

• Thermal aging test (NTC 7140 – 70 °C for 7 days) – the gel sample is stored in an oven at 70 °C for 7 days, and then its gel strength (Bloom, compression, or penetration) is re-measured. We report the change in gel strength and the percentage retention.
• Humidity aging test (NTC 7141 – 40 °C and 90 % RH for 7 days) – the gel is exposed to high humidity (90 % RH) at 40 °C for 7 days, and then its gel strength is re-measured. We report the change in gel strength and any visible signs of degradation (e.g., weeping, syneresis, or mold growth).
• Light exposure test (NTC 7142 – UV light for 500 hours) – the gel is exposed to UV light (UVA-340) for 500 hours, and its gel strength is re-measured. We report the change in gel strength and any discoloration or degradation.
• Freeze-thaw cycle test (NTC 7143 – 5 cycles from -20 °C to +20 °C) – the gel is subjected to 5 freeze-thaw cycles (e.g., from -20 °C to +20 °C), and its gel strength is re-measured after each cycle. We report the gel strength after each cycle and the stability of the gel.
• Chemical stability test (NTC 7144 – exposure to pH variation or active ingredients) – the gel is exposed to different pH values (e.g., 4, 7, 9) or to active ingredients (e.g., drugs, acids) for 7 days, and its gel strength is re-measured. We report the gel strength after exposure and any chemical incompatibility.

Complementary Tests – Composition Analysis, Moisture, and pH

To provide a comprehensive assessment of the gel's properties and to correlate the gel strength with its chemical composition, we complement the mechanical tests with compositional and physicochemical analyses. These tests are essential for formulation development and for ensuring consistent product quality.

• Moisture content (ASTM D2216 / NTC 7150 – for gels and powders) – we measure the moisture content of the gel (or the gelling agent) using the oven-drying method (or by Karl Fischer titration for low moisture). We report the moisture content (in %) and its correlation with the gel strength.
• pH measurement (ASTM E70 / NTC 7151 – for liquid and gel samples) – we measure the pH of the gel using a calibrated pH meter, which is essential for characterizing the gel's chemical environment, as pH can affect gel strength. We report the pH value.
• Ash and mineral content (ASTM D3685 / NTC 7152 – for inorganic fillers and additives) – we measure the ash content (by incineration) and the mineral content (by ICP or AA) to quantify the amount of inorganic fillers in the gel. We report the ash content and the mineral composition.
• Density (ASTM D792 / NTC 7153 – for gels and liquids) – we measure the density of the gel using a pycnometer or a hydrometer. We report the density (in g/cm³) and its correlation with the gel strength.
• Viscosity measurement (ASTM D2196 / NTC 7154 – for liquid gels and solutions) – for gels that are in a liquid state at elevated temperatures, we measure the viscosity (using a rotational viscometer) at the processing temperature. We report the viscosity (in mPa·s) and the temperature.

Test Report and Recognition in the Colombian Food, Pharmaceutical, and Cosmetic Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (Bloom testers, universal testing machines, rheometers, pH meters, etc.) and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the sample (gel type, composition, concentration, manufacturer, lot number, and intended application).
• Detailed description of the test methods applied (ASTM/ISO/NTC standards, test temperature, conditioning, and test speed).
• Numerical results: Bloom strength (g), penetration depth (mm), compressive strength (kPa), storage modulus (G', Pa), loss modulus (G'', Pa), yield stress (Pa), tensile strength (MPa), and gel melting temperature (°C).
• Graphical data: stress-strain curves, frequency sweeps, amplitude sweeps, and temperature ramps.
• Comparative tables against the values specified by the client or against the limits of the NTC 7100 (Bloom strength), NTC 7110 (Compression), NTC 7120 (Rheology), and the requirements of the INVIMA, SIC, and DIAN for quality and safety certification.
• Photographs of the gel samples before and after testing, showing the deformation, fracture, or consistency.
• Recommendations for formulation optimization, process control, and quality assurance to achieve the desired gel strength.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA) for the registration and certification of food, pharmaceutical, and cosmetic products, by the Superintendencia de Industria y Comercio (SIC) for product quality and safety compliance, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of gels, gelling agents, and gel-based products. Additionally, we offer consulting services for the selection of gel-forming agents, the design of gel formulations with specific gel strength, and the implementation of quality control programs to ensure consistent gel performance, contributing to the quality, stability, and consumer satisfaction of products in the diverse Colombian market, from the food industry to the pharmaceutical and cosmetic sectors.