Stability Testing for Cosmetics
What is stability testing for cosmetics?
Stability testing of cosmetics is the process of evaluating the physical, chemical and microbiological stability of the product over a specified period. This test simulates real-world conditions wherein the product will be subjected to various conditions of storage, transportation and usage. The main purpose of this test is to determine how the product behaves and responds to these varying conditions and to ensure that the product remains safe, effective and appealing throughout its intended shelf-life.
The testing process involves assessing factors such as temperature, humidity, light exposure and packaging interactions to detect potential changes in color, odor, viscosity and microbiological contamination. Stability tests allow the manufacturer to determine the shelf life of a product and the best condition for its storage.
Types of stability test
Several tests must be conducted to ensure the stability of the product. Stability testing of cosmetics includes the following tests:
Physical and chemical integrity
Physical and chemical stability testing of the product involves assessing its appearance, texture, viscosity and pH levels. Any change in one of these parameters would alter the performance of a product, making it less effective or changing its sensory experience. For example, creams or lotions may separate and colors may fade over time. By testing these aspects under controlled conditions, manufacturers can rest assured that the cosmetic product retains its desired characteristics.
This testing often includes exposure to heat, freezing and light in order to simulate how a product might degrade with time. It is essential to look for phase separation, precipitation, or color changes in the cosmetic formulation.
Microbiological stability
Microbiological stability is of paramount importance as it ensures cosmetics are not contaminated with pathogenic microbes over time. Since most cosmetic products contain water, they can easily become ideal breeding grounds for most bacteria, yeast and mold if not properly preserved. Microbiological testing assesses the effectiveness of preservatives and ensures the product remains free from contamination throughout its shelf life.
Microbiological testing of cosmetics often includes the challenge test and preservative efficacy tests. These tests are conducted in accordance with international standards. A product showing any sign of contamination does not get approval for market release as it could pose health risks to consumers.
Some of the commonly followed standards include:
USP test methods
- USP 51: Antimicrobial Effectiveness Testing
- USP 61: Microbial Enumeration Test
- USP 62: Microbial Enumeration of Non-Sterile Products: Tests for Specified Microorganisms
PCPC standards
- PCPC M-1 – Determination of the Microbial Content of Cosmetic Products
- PCPC M-2 – Examination for Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa
- PCPC M-3 – Preservation Testing of Water-Miscible Personal Care Products
ISO standards
Types of organisms used
In microbiological stability testing, specific types of microorganisms are used to challenge the preservative system of cosmetics. Commonly tested organisms include:
- Staphylococcus aureus
- Escherichia coli
- Candida albicans
- Aspergillus brasiliensis
These organisms represent potential contaminants that the cosmetic may be exposed to during the production stages or consumer use. Therefore, it is essential to ensure that the product is resistant to these microorganisms for its safety and longevity.
Packaging stability
The proper packaging of the cosmetic product is essential for the overall stability of a cosmetic. Packaging stability testing assesses the level of protection a packaging system offers to the product against environmental factors, such as light, air, or moisture. The interaction between a cosmetic product and its packaging may also result in compositional changes that can even lead to contamination or degradation.
Testing involves checking for leachables or extractables from the packaging materials, the container’s ability to retain a proper seal and evaluating the resistance of the package to fluctuating temperatures.
Regulatory and compliance
Cosmetic products are subject to various regulatory standards to ensure consumer safety. Organizations such as the FDA in the United States and the European Commission have strict regulations on the stability testing of cosmetics. These regulations require evidence from manufacturers that their cosmetic products are stable and safe for consumers during their shelf life.
Compliance with these regulations not only safeguards the end-user but also enhances the credibility of cosmetic goods in the market. Failure to meet any of the regulations will lead to product recalls, legal issues, or market withdrawal.
Steps for cosmetic shelf life and stability testing
Initial assessment
The first step in stability testing of cosmetics is to carry out an experimental analysis of the cosmetic to understand its properties and determine what parameters need to be monitored. This assessment involves taking into account various aspects of the cosmetic such as the formulation’s composition, the type of product (e.g., cream, lotion, serum) and any known sensitivities of the product to environmental conditions such as light or temperature.
Testing under controlled conditions
For stability testing, cosmetics are subjected to various controlled environmental conditions to simulate real-world storage or transportation. Testing under controlled conditions usually takes several months, depending on the shelf-life of the product. The product samples are tested and observed at regular intervals to identify changes in their physical, chemical, or microbiological characteristics.
Physical, chemical, microbiological evaluations and packaging stability testing
During the testing phase under controlled conditions, the cosmetic product is subjected to various evaluations, including physical (appearance, viscosity), chemical (pH and concentration of active ingredients), microbiological evaluations and packaging stability testing.
Shelf life prediction
Experts could determine the shelf life of the cosmetic product based on the results of tests. This involves comparing the current data against the product’s performance benchmarks. If the product stays stable over a certain period under the applied test conditions, manufacturers can recommend an appropriate shelf life for the product.
Shelf life predictions may involve:
- Real-time stability testing
In this approach, products are stored at normal conditions and their stability is assessed over the intended shelf life period.
- Accelerated stability testing
This testing accelerates the aging process by subjecting products to more extreme conditions than they would typically experience.
Report generation
A detailed report is generated that provides insights into the product performance under each test condition. The report will highlight potential issues that may arise, such as changes in appearance, degradation of ingredients, or the presence of microorganisms and provide a final verdict about the product’s stability and shelf life. This report can be used to further develop a product or help manufacturers ensure compliance with regulations.
Importance of stability testing
Cosmetic products must be able to retain their intended quality and safety throughout their shelf life. Stability testing of cosmetics is important for the following reasons:
- Consumer safety
Stability testing will ensure that products liable to degradation or contamination don’t reach the market.
- Regulatory compliance
It helps manufacturers meet legal requirements and avoid penalties or recalls.
- Brand reputation
A stable product is unlikely to lead to complaints or negative reviews that could damage the brand.
- Cost-effectiveness
Issues of stability could be identified much earlier in the development process of the product to avoid costly recalls and reformulations later on.
Why choose stability testing of cosmetics at MIS?
At MIS, we use state-of-the-art testing facilities and methodologies to evaluate the physical, chemical, microbiological and packaging stability of your cosmetic formulations. We provide clear, detailed reports to help you understand the test results and make informed decisions for your product’s development and market launch.
For additional information regarding our stability testing of cosmetics or to discuss your specific needs, contact the experts at Microbe Investigations Switzerland today.
FAQs on Stability testing for cosmetics
Stability testing of cosmetics is the process of determining how a cosmetic product will perform in different conditions over time to ensure it is safe and effective throughout its shelf life.
Stability testing cosmetic services can take from a few months up to a year or more, depending on whether real-time or accelerated testing is done.
Real-time testing evaluates a product under normal storage conditions, whereas accelerated testing puts a product under extreme conditions to predict how long it will last before expiring.
Microbiological stability ensures that a cosmetic product will remain free from harmful microorganisms that could compromise its safety, spoilage and cause other detrimental effects.
Shelf-life determination involves estimating how long a cosmetic product will remain stable and effective based on the results of stability testing.
Packaging may interfere with stability either by reacting with the product or failing to protect it against exposure from several environmental factors including air, light, or moisture.
Yes, climate significantly influences stability, particularly in high-temperature and high-humidity regions.
If the product fails the stability test, it must be reformulated or recalled and manufacturers must take corrective actions to address the issue.
Get your product tested now
✓ Completed test order form (TOS)
✓ Customization and Assistance to determine the right test for your project
✓ FAST TRACK Program with less Turnaround Time
