Setting a shelf life for ambient food
By Reka Haraszi - 12 October 2018
Providing an indication of minimum durability is a legal requirement for most ambient food and drink products. How to set a ‘best before’ shelf life date for ambient goods is a commercial decision. Parameters that contribute to this decision are the quality, the safety, logistics and customer requirements. A date of minimum durability (i.e. a ‘best before’ date) means the date until which the food retains its specific properties when properly stored.
Shelf life testing for ambient goods needs to be done on a case-by-case basis by assessing what limits product life and what is the length of the intended storage.
Shelf life limiting factors
There are some situations where the shelf life of the product is driven by regulatory constraints, for example if the product has a nutritional claim associated with it. If the claimed level of nutrient is not maintained before the quality declines, this will be the shelf life limiting factor. Likewise, if there is a migration issue, for example tin in a canned product and the level of tin exceeds the maximum regulatory limit of 200 mg/kg before the quality of the product declines then this will be the shelf life limiting factor. In case of no regulatory or labelling claims, colour change, flavour change or texture change may cause the end of life.
Accelerated shelf life assessment
The most direct way of determining shelf life is to carry out storage trials under realistic, defined conditions. While accelerated methods and simulated modelling can be used, they must be used with care; elevated temperature is the most commonly used acceleration factor, and this can cause chemical and microbiological changes that would not occur at ambient temperatures. Accelerated testing can only be used if the tests have been validated against ambient shelf life trials. However, commercial pressures mean manufacturers want to get their product on the shelves as quickly as possible. In these situations, one approach is to carry out the shelf life assessment at ambient temperatures and get the product to market with a modest best before date. Once the product is on sale, reference samples can be taken and stored. The shelf life of the product can then be tested over a longer period and extended on a rolling basis, while continuing with shelf life extension trials.
When do you need to reassess shelf life?
Shelf life assessment isn’t only necessary during new product development, it must also be reassessed if you make a change to an ingredient, supplier, process or packaging. It’s unlikely the full shelf life assessment will need to be repeated – an experienced shelf life assessor can predict the likely effects of any changes made to the product so that only the tests necessary for the parameters that have changed will need to be repeated. For example, changing a high moisture barrier film of a bakery product to low barrier but more sustainable packaging will require testing for moisture uptake.
There is no specific legislation on how to set a shelf life for ambient stable goods. The FDF has produced a guideline document which outlines some of the things that need to be considered. Manufacturers can use shelf life testing as evidence of due diligence for retailer standards. Accurate shelf life assessment can also help to reduce food waste.