Stability testing

This test determines the acid value of oils, fats, and fat-containing dietary supplement ingredients using the official AOCS Ca 5a-40 titration method. The acid value is a direct measure of the free fatty acid (FFA) content present in a lipid sample and is a primary indicator of oil quality, freshness, and degree of hydrolytic degradation. Elevated acid values indicate hydrolytic rancidity, improper storage, or poor raw material quality. Results are reported in mg KOH/g of sample and are used for raw material qualification, shelf-life assessment, and compliance with product specifications.

A representative sample of known weight is dissolved in a neutralized ethanol-diethyl ether solvent mixture. The solution is titrated with a standardized potassium hydroxide (KOH) solution in the presence of a phenolphthalein indicator until a persistent pink endpoint is reached. The acid value is calculated from the volume of KOH consumed relative to the sample weight, expressed as mg KOH per gram of sample, per the AOCS Ca 5a-40 official method. Blank titrations are run concurrently to correct for any acidity in the solvent system.

Acid value is one of the most fundamental quality parameters for lipid-based ingredients and is required by most raw material specifications for fish oils, MCT oils, seed oils, and fat-soluble vitamin carriers. An out-of-specification acid value is a reliable early indicator of hydrolytic rancidity and can predict downstream quality issues including off-flavors, reduced potency of co-formulated actives, and consumer safety concerns. AOCS Ca 5a-40 is the globally recognized official method for this determination, ensuring results are comparable across suppliers, labs, and regulatory frameworks.

This analysis detects and quantifies foreign matter—such as stems, soil, stones, plastics, or other non-declared materials—in botanical, powdered, or granular ingredients. It ensures that plant-derived or food-grade materials meet pharmacopeial purity standards and are free from contamination or adulteration.

A representative sample is visually examined on a clean, flat surface under adequate lighting. Foreign matter is manually separated, weighed, and reported as a percentage of the total sample weight. The method typically follows USP <561>, EP 2.8.2, or equivalent quality standards for botanicals and herbal products.

Results are reported as % w/w (percent by weight). Acceptable limits vary by material but are often ≤2%. This test confirms material integrity and detects contamination that could compromise product safety or quality.

This assay quantifies residual oxygen and carbon dioxide in the headspace of packaged products. O₂ and CO₂ levels provide critical information about product freshness, microbial stability, and packaging effectiveness.

Packaged samples are analyzed for headspace gas composition under controlled conditions. Oxygen and carbon dioxide concentrations are measured directly using validated gas analysis instrumentation.

Results are reported in % O₂ and % CO₂ by volume. Monitoring headspace gases ensures packaging performance, confirms modified atmosphere or nitrogen flushing effectiveness, and helps predict shelf-life stability.

This test determines the melting point of a solid raw material or ingredient using the method described in USP <741> (Melting Range or Temperature). The melting point is a fundamental physical characteristic used to confirm the identity and assess the purity of a substance — impurities and polymorphic variations typically cause a depression or broadening of the expected melting range. This test is commonly applied to pharmaceutical-grade excipients, active ingredients, fatty acids, waxes, and other solid materials where melting point is a defined specification parameter. Results are reported as the observed melting range in degrees Celsius (°C) and compared against the USP monograph or supplier specification.

A small quantity of the dry, finely powdered sample is introduced into a capillary tube, which is placed in a calibrated melting point apparatus. The temperature is raised at a controlled, defined rate as specified in USP <741>. The temperature at which the sample begins to liquefy (onset) and the temperature at which it is completely melted (clear point) are recorded. The observed melting range is compared against the reference specification for the material under test. The apparatus is calibrated using certified melting point reference standards prior to sample analysis to confirm temperature accuracy.

Melting point determination is one of the oldest and most straightforward physical identity tests in pharmacopoeial analysis, and is required or recommended in numerous USP ingredient monographs as a rapid, non-destructive means of confirming material identity and detecting gross impurities or adulteration. A melting point that falls outside the expected range — or a broadened melting range — can indicate the presence of impurities, incorrect polymorph, or substitution with a different material. USP <741> provides a standardized, validated procedure that supports raw material qualification and cGMP compliance under 21 CFR 111.

Assay that measures the moisture content in food products (using the “loss on drying” technique) to support labeling and quality control. It ensures that water levels meet regulatory and formulation standards, maintaining product stability and consumer acceptance.

Samples are accurately weighed, then placed in a controlled environment and heated to remove moisture. The weight difference before and after drying is measured to calculate the moisture content. Calibration with reference materials and replicate measurements ensure precise and accurate results.

Results are expressed as a percentage (%) of moisture for each sample. These values confirm that the product meets regulatory requirements and specified quality parameters, while consistency across batches indicates controlled manufacturing and reliable ingredient sourcing.

This test evaluates the key organoleptic and physical characteristics of a product, including appearance, color, odor, packaging integrity, and texture, through structured sensory inspection. Organoleptic testing is a critical component of incoming raw material and finished product release testing, providing a rapid first-line assessment of product identity, quality, and consistency before more detailed analytical testing is performed. Results are reported as pass/fail against predefined product specifications.

A representative sample is visually and physically inspected by a trained analyst under standardized lighting and environmental conditions. Each attribute — appearance, color, odor, packaging integrity, and texture — is evaluated against documented product specifications and reference standards. Observations are recorded on a standardized inspection form, and any deviation from specification triggers further investigation or rejection. Packaging integrity is assessed for seal quality, label accuracy, and absence of damage or contamination.

Organoleptic evaluation is one of the most fundamental quality control checks in the supplement and food industry. Deviations in color, odor, or texture can indicate ingredient degradation, contamination, incorrect raw materials, or a manufacturing process failure — issues that may not be immediately apparent from chemical testing alone. Establishing a documented sensory inspection protocol ensures consistent, reproducible assessments across analysts and batches, supporting cGMP compliance and reducing the risk of releasing non-conforming product.

This assay measures the p‑anisidine value, which quantifies secondary oxidation products (aldehydes) in fats and oils. It provides an indication of the extent of oxidative deterioration during storage or processing, serving as a key quality parameter for fat freshness.

A measured fat sample is reacted with a p‑anisidine reagent under controlled conditions. After incubation, the intensity of the color developed is measured by spectrophotometry. The absorbance is then converted to a p‑anisidine value using a calibration factor derived from standard solutions. Duplicate analyses and quality controls ensure reliable results.

Results are presented as a numerical value; lower values indicate minimal oxidation and fresher fat quality, while higher values suggest increased oxidation and potential rancidity. These values help manufacturers monitor shelf life and determine the need for antioxidant interventions.

This test measures the particle size distribution of a powder or granular material by passing it through a single mesh sieve of a defined aperture size, as specified in USP <786> (Particle Size Distribution Estimation by Analytical Sieving). It determines the percentage of material retained on or passing through the sieve, providing a direct measure of compliance with particle size specifications. The test is applicable to raw material powders, excipients, and granulated finished products. Results are reported as the percentage retained (or passing) at the specified mesh size.

A pre-weighed sample is loaded onto a single sieve of the specified mesh size and subjected to mechanical agitation for a defined duration under controlled conditions, per USP <786>. Following sieving, the mass retained on the sieve and the mass passing through are each weighed. The percentage retained and percentage passing are calculated relative to the initial sample weight. The sieve is inspected before and after use to confirm mesh integrity, and results are reported against the product-specific acceptance criterion.

Particle size directly affects the physical and functional properties of powders and granules, including blend homogeneity, flowability, compressibility, and dissolution rate. A single-mesh sieve test provides a rapid, cost-effective pass/fail assessment against a defined specification, making it a standard incoming quality control check for raw materials and an in-process control for granulation and milling operations.

This test measures the particle size distribution of powders, granules, and liquid suspensions using laser diffraction, per USP <429> (Light Diffraction Measurement of Particle Size). Laser diffraction measures the angular pattern of light scattered by particles as they pass through a laser beam, generating a full particle size distribution curve with key reporting parameters including D10, D50, D90, and span values. Unlike single-mesh sieve testing, laser diffraction characterizes the complete size distribution across the full sample population, making it the preferred method for fine powders, micronized ingredients, and nanosuspensions where sieve analysis is impractical. Results are reported in micrometers (µm).

A representative sample is dispersed in either a dry powder module (for free-flowing powders) or a liquid dispersant medium (for fine or cohesive powders and suspensions) appropriate to the material being tested. The dispersed sample is passed through the laser beam of the diffractometer, and the angular light scattering pattern is measured and converted to a particle size distribution using Mie or Fraunhofer optical theory, as appropriate for the particle size range and refractive index of the material.

Particle size is a critical quality attribute that directly influences the dissolution rate, bioavailability, flowability, blending uniformity, and aerosolization performance of powdered ingredients. Laser diffraction provides a rapid, reproducible, and high-resolution full distribution profile that is far more informative than a single-point sieve result, making it the method of choice for micronized actives, botanical powders, and any ingredient where particle size is a defined specification parameter.

This assay determines the peroxide value of fats and oils, indicating the extent of primary oxidation. It measures the concentration of hydroperoxides formed during processing or storage, serving as an indicator of product freshness and stability.

A measured fat sample is dissolved in a suitable solvent and reacted with the reagents provided in the test kit. The resulting color change is measured by UV/Vis spectrophotometry. The absorbance is converted to a peroxide value using a calibration factor from standard solutions, and duplicate tests ensure reliability.

Results are reported in milliequivalents of peroxide per kilogram of fat. Lower values suggest fresher, less oxidized fat, while higher values indicate increased oxidation that may affect flavor and shelf life. The numerical data help manufacturers assess storage conditions and antioxidant effectiveness.

This assay measures the pH level of food, supplement, or cosmetic products to assess acidity or alkalinity. pH is a critical parameter for product stability, microbial safety, and regulatory compliance. It helps guide formulation adjustments and supports claims related to digestive health, skin compatibility, and shelf life.

Samples are homogenized and diluted (if required) according to matrix-specific protocols. pH is measured using a calibrated glass electrode and pH meter, compliant with standardized methods (e.g., AOAC, USP). Routine calibration is performed using certified buffer solutions (pH 4.0, 7.0, and 10.0), and measurements are conducted in duplicate to ensure precision and consistency.

Results are reported as unitless pH values, typically to two decimal places (e.g., 4.75). These values indicate the product’s acidity or alkalinity and are assessed against specification ranges for quality control, formulation integrity, and compliance. Deviations from expected pH may signal contamination, formulation drift, or stability issues that require corrective action.

This assay quantifies the combined content of dissolved substances such as minerals, salts, metals, and organic compounds. TDS is a key indicator of water purity, taste, and suitability for use in food, beverage, and supplement manufacturing.

Samples are analyzed for total dissolved solids by measuring the residue left after evaporation and drying of the filtrate, or by correlation with conductivity measurements. Quality controls confirm accuracy and reproducibility.

Results are reported in mg/L (ppm). Monitoring TDS ensures compliance with water quality standards, identifies potential contamination, and supports consistent product formulation.

This test determines the Total Oxidation Value (TOTOX) of oils, fats, and lipid-containing dietary supplements using a calculated method that integrates two complementary oxidation markers: the Peroxide Value (PV), which measures primary oxidation products (lipid hydroperoxides), and the Anisidine Value (AV), which measures secondary oxidation products (aldehydes, principally 2-alkenals). TOTOX is calculated using the established formula: TOTOX = 2 × PV + AV. Because PV and AV measure different stages of the lipid oxidation cascade, TOTOX provides a more complete and reliable picture of overall oxidation status than either parameter alone — PV reflects current oxidation activity while AV reflects the cumulative history of oxidation. TOTOX is widely used for quality control of fish oils, omega-3 concentrates, vegetable oils, and other lipid-rich dietary supplement ingredients. Results are reported as a dimensionless TOTOX value, with industry-standard limits typically set at ≤ 26 for fish oil (GOED voluntary monograph) and similar thresholds for other oil types.

TOTOX is calculated from the results of two independently performed oxidation assays conducted on the same representative sample. The Peroxide Value (PV) is determined by iodometric titration (AOCS Cd 8b-90 or equivalent), in which lipid hydroperoxides oxidize iodide to iodine, which is then titrated with standardized sodium thiosulfate solution; results are expressed in milliequivalents of active oxygen per kilogram of oil (meq O₂/kg). The Anisidine Value (AV) is determined by UV-Vis spectrophotometry (AOCS Cd 18-90 or equivalent), in which p-anisidine reacts with aldehydic secondary oxidation products to form a colored Schiff base measured at 350 nm; results are expressed as a dimensionless absorbance-based value. The TOTOX value is then calculated by applying the formula TOTOX = 2 × PV + AV to the individually determined PV and AV results.

Neither PV nor AV alone provides a complete assessment of lipid oxidation status: PV reflects only current hydroperoxide levels and can decrease as oxidation progresses to secondary products, while AV captures the accumulated aldehyde burden but does not reflect active peroxide formation. The TOTOX calculation integrates both parameters to provide a single composite index that accounts for both the current and historical oxidation status of the oil, making it a more robust and informative quality indicator than either measurement in isolation. TOTOX is the standard composite oxidation index used by the Global Organization for EPA and DHA Omega-3s (GOED) and other industry bodies for fish oil and omega-3 product quality specifications, and supports raw material qualification, finished product release, and cGMP compliance under 21 CFR 111.

This assay evaluates the cloudiness or haziness of a liquid caused by suspended particles. Turbidity is an important indicator of water quality, processing effectiveness, and potential contamination.

Samples are analyzed for light scattering caused by suspended particles under controlled conditions. Results are compared against regulatory or internal quality specifications.

Results are reported in Nephelometric Turbidity Units (NTU). Monitoring turbidity ensures compliance with drinking water regulations, confirms process consistency, and protects product quality.

This assay measures water activity (aw), which indicates the amount of free, unbound water in a product that is available to support microbial growth and chemical reactions. Water activity is expressed on a scale from 0.00 to 1.00, with higher values indicating greater potential for microbial activity. It is a key parameter for predicting shelf stability and safety in foods, supplements, and other consumable products.

Samples are placed in a sealed measurement chamber and analyzed using a calibrated water activity meter. The device determines the equilibrium relative humidity of the air surrounding the sample, which is converted into the aw value. The method follows AOAC, ISO, or ASTM guidelines for water activity

Results are reported as a unitless aw value (e.g., 0.35).