Stability Testing For Quality Control

If there was an industry that needs to make sure that it can deliver on its promises and, that its products perform above and beyond expectations, the cosmetic business is probably it.

A manufacturer’s worst nightmare is having their reputations left in tatters due to customer complaints about the product separating, becoming contaminated or leaking. Stability testing involves the laboratory testing of cosmetic products in different environment/storage conditions for a set period, in order to simulate what will happen to the product during its life cycle.

When to do stability testing?

Stability testing needs to be carried out primarily on new product development, it is also critical to repeat new stability tests should you change an ingredient or supplier; move to a new production site; change equipment or manufacturing procedure; scale up production from a smaller to larger batch; adopt new packaging or if there is a change in regulations.

Apart from the normal parameters tested such as pH, SG, viscosity and odour and appearance – speciality products such as soap can be tested for weight loss and aerosol cans can be tested to ensure uniform sprayability.  Performance tests also need to be conducted on certain high-end creams, to ensure the level of active ingredients is still stable at the end of shelf life. The actual tests conducted will also depend on the product or package.

Types of stability testing

Stability testing is done to ensure a new or modified product meets the intended physical, chemical and microbiological quality standards as well as functionality and aesthetics when stored under appropriate conditions.

Basic stability testing

Basic stability testing starts off very simply to see how a product behaves in the short-term as a predictor for longer-term stability.  This includes freeze/thaw testing, centrifuge analysis and microscopic evaluation.   Samples are held in hot environment for a short period, for example, a week, to see how they fare.  If that stage is passed samples progress to a more standard protocol of 4C, Room Temp and 40C conditions over 12 weeks, which is equivalent to a 2-year shelf life – the recommended shelf life for a typical cosmetic.

Accelerated stability tests

These accelerated stability tests are normally used to put a product on the shelf quickly, but they should not replace real time stability where you validate that the accelerated stability testing does give you the shelf life that you have claimed on your packaging.  Real life stabilities should be carried out so that if you claim 2 years – you can prove that the shelf life actually is 2 years.

During stability testing, the product may be exposed to:

• Microbial challenges
• Freeze/thaw testing
• Centrifuge analysis
• Packaging compatibility

At this stage, there are no specific regulations governing stability testing, but guidelines are given by ISO.  The value in stability testing lies in being able to put a product on the shelf that you are confident will remain stable and therefore be able to live up to the claims and promises made on the packaging.

Testing of stability should be carried out when an independent result is required, such as first production runs for a customer or if you do not have the equipment or space to store specific samples.

Stability testing is a manufacturer’s guarantee to the customer that they are delivering a quality product that they can trust. STABILITY TESTING SERVICES is a division of Botanichem and offers a well-equipped onsite laboratory for independent stability testing for the cosmetic industry.

If you would like to learn more about stability testing or are interested in having your products tested, please email robyn@botanichem.co.za or give us a call on 011 425 2206