Microbiological accelerated shelf–life testing
Commercial pressure from the short time–frame for the product development cycle has led to many requests for accelerated shelf life testing. This is possible in some cases, but it requires an understanding of product composition and whether (and when) accelerating conditions cause a switch of spoilage mechanisms. We have used microbial growth prediction models and actual growth data to generate data for the growth of naturally occurring mixed spoilage flora at a range of temperatures. This allowed us to determine if and where a spoilage ‘switch’ occurs, to give us an indication of realistic versus non–relevant ‘accelerated’ conditions.
Cooked meat and dairy dessert trials
For example, in a cooked meats trial, we found Enterobacteriaceae to be the main spoilage group, and derived comparable results with predictive models above 5°C. Data suggests that it is possible to produce a formula for cooked meats where: x days at 22°C = y days at 8°C. When testing a cooked meat in which lactic acid bacteria were found to be the main spoilage group, a similar formula could still be applied.
With a dairy dessert, a switch in primary spoilage organisms occurred, with yeast more significant at lower temperatures, and TVC above 15°C. This suggests that accelerated testing would not be possible for this type of product.