Product stability testing helps manufacturers understand how cosmetics, personal care products and pharmaceuticals perform over time under defined storage conditions. By assessing products under defined storage conditions, stability testing provides information about how formulations change over time and whether further development work may be required. Working with an experienced manufacturing partner like Delta helps brands plan stability testing as part of the wider product development and manufacturing process.
What Is Product Stability Testing?
Product stability testing evaluates how a product’s physical, chemical and microbiological properties change over time under different environmental conditions. The goal is to monitor how a formulation changes over time and assess whether it continues to meet its defined specifications.
For manufacturers, stability testing provides the scientific data needed to support:
- Shelf-life assessment
- Product specifications
- Relevant regulatory requirements
- Ongoing product development decisions
A structured stability testing protocol provides a consistent way to monitor the product over time and record any changes that may need further investigation.
Purpose and Importance
Stability testing helps answer critical questions during product development and regulatory review:
- How does the product change over time under defined storage conditions?
- Will the formulation separate, degrade or change colour?
- Does the packaging protect the product adequately?
- How do defined temperature and humidity conditions affect the product over time?
For cosmetic and pharmaceutical products, stability testing provides useful information during development and can help identify whether further formulation or product review is required before launch.
Types of Stability Testing
A stability testing program may assess several characteristics, depending on the product and its requirements.
Physical Stability
Physical testing looks at visible and structural changes in the product, such as:
- Colour changes
- Phase separation
- Texture or viscosity changes
- Sedimentation or crystallisation
These factors can affect both product performance and consumer perception.
Chemical Stability
Where relevant, stability testing may include analytical testing to monitor specified active ingredients over time. The testing required will depend on the product type, formulation and applicable requirements.
Microbiological Stability
Microbiological testing can be included as part of the testing program where relevant to the product. This is particularly important for water-based cosmetic formulations.
Testing may include:
- Bacterial, Yeast and Mould testing
- Preservative efficacy testing
How Delta Performs Stability Testing
At Delta, stability testing is designed to provide data that supports product development and relevant regulatory requirements.
Protocol Development
A stability study begins with a testing protocol developed around the product and its requirements.
This protocol typically defines:
- Testing duration
- Storage conditions
- Sampling intervals
- Analytical tests to be performed
- Acceptance criteria
The protocol sets out how the study will be conducted and how results will be assessed over the testing period.
Temperature and Humidity Conditions
Environmental conditions play a major role in product stability. Testing commonly evaluates how formulations respond to different temperature and humidity levels over time.
At Delta, 30°C / 65% RH is a typical long-term stability condition.
Stability Testing for Cosmetics and Pharmaceuticals
Different industries have specific regulatory expectations when it comes to stability testing.
Key Industry Requirements
Stability requirements vary depending on the type of product and its regulatory pathway.
For pharmaceutical or therapeutic products, stability data may be required to support:
- Expiry dating
- Storage conditions
- Product registration
The testing program should be developed with the relevant product and regulatory requirements in mind.
Interpreting Stability Test Results
Collecting stability data is only part of the process. The results are reviewed to assess how the product is performing against its defined specifications over the study period.
Data Reporting and Actions
At scheduled intervals during a stability study, samples are tested and the results are recorded. These data points help identify trends such as:
- Changes in relevant product specifications
- Changes in pH or viscosity, where applicable
- Microbiological results, where relevant
- Observations that may require further investigation
If results fall outside the expected specifications, further review or development work may be required.
Why Choose Delta
Choosing an experienced manufacturing partner is important when planning and managing stability testing. Delta supports cosmetic, personal care and pharmaceutical manufacturers through:
- Stability testing protocols developed around the product and its requirements
- Long-term and accelerated stability studies, where applicable
- Recording and reporting of stability results
- Stability testing as part of the wider product development process
With practical experience across product development and manufacturing, Delta helps brands understand how their products perform over time and make informed decisions before market launch.
Need support with product stability testing?
Delta works with cosmetic, personal care and pharmaceutical brands to develop stability testing programs suited to the product and its requirements.
Speak with Delta’s team about stability testing requirements for your product.