It is also part of ISO 22000 standards. One of the objectives is to align food safety and quality standards to reduce food recalls and improve food safety and protection through the global supply chain. This standard has been around for about 10 years but is becoming more common in the last couple of years in the United States.
At Clemson University, we’ve experienced an increased number of food companies requesting information on shelf-life testing as well as performing shelf-life testing. Third-party validation of product shelf life is necessary if companies do not have the facilities for shelf-life testing internally. Another reason for third-party testing is that the results are considered more valid when they come from a third-party test lab, which is apparently a positive for GFSI audits. Since more people are considering doing their own shelf-life testing or looking for a test site, it is a good idea to understand the basics of shelf-life testing in order to know what to ask for and look for in a good test.
Shelf-life testing is a process for food companies that was originally adopted by the medical and pharmaceutical industry. There are several theories of how shelf life should be measured and/or calculated, but the generally accepted method is the Q10 method. This means that for every 10°C incremental increase, the reaction rate doubles. For example, if room temperature is 23°C and the shelf life of your product at room temperature is 2 years, you could store your product at 43°C for 6 months to validate the shelf life.
One of the assumptions made during accelerated shelf-life testing using the Q10 method is that the reaction occurring is linear (steady state). This is a safe assumption if the main quality factor being measured is moisture gain or loss, but it’s not always a safe assumption if nutritional changes are measured. An alternative to this method is to determine the energy of activation for a given reaction (for example, enzymatic color degradation), determine if the reaction is linear or non-linear, then design the experiment and calculations based on this knowledge. Most companies do not have the time, expertise or lab equipment to perform these experiments. In addition, accelerated shelf-life testing for refrigerated or frozen foods is designed differently than for shelf stable products.
To get the most from shelf-life testing and help fulfill GFSI Certification for your product, be sure you know the following: moisture content, water activity, storage conditions, distribution chain, most significant factor for determining end of shelf life, and microbiological considerations. Another important issue is whether shelf life is to be validated using objective (instrumental) or subjective (sensory) methods or both methods. Third-party testing can be a significant investment, but it’s necessary if GFSI Certification is being sought. pw
Kay Cooksey (kcookse@exchange.clemson.edu), PhD, is a professor and the Cryovac Chair at Clemson University’s School of Packaging.
