Shelf-life study and date marking checklist

Define the question

• The product is fully described: formulation, pH, water activity, preservatives, process (including the kill step), packaging (material, gas, seal) and the storage and distribution conditions it will actually see.
• The failure modes are listed before the study starts: pathogen growth, spoilage (microbial, chemical, physical), sensory change, nutrient loss, packaging failure, and which one is expected to end the shelf life.
• The intended consumer and use are stated, including vulnerable groups.
• The date type is decided before the study starts: 'use by' where pathogen growth or toxin ends the shelf life (as Codex recommends), or 'best before' where quality ends it. R146 permits either.
• Relevant history has been gathered: similar products, supplier data, literature, predictive models and complaint records.

Design the study

• Storage conditions in the study reflect the real chain, including the abuse that is reasonably foreseeable (a warm vehicle, a domestic fridge at 7 °C, an opened pack).
• The number of batches, samples per time point and time points are set so that the result is statistically defensible, and the sampling plan is written down.
• Tests are chosen for each failure mode: pathogens of concern (for example Listeria monocytogenes, Salmonella, Clostridium botulinum where the product allows), spoilage organisms, chemical markers (peroxide value, pH, moisture), physical attributes and a trained sensory panel.
• Accelerated studies are used only where the degradation mechanism is known to follow the acceleration model, and the result is confirmed by a real-time study.
• A challenge test is planned where a pathogen could grow in the product and the formulation or process is relied on to stop it.
• The laboratory is SANAS accredited (ISO/IEC 17025) for the methods used, and the methods, detection limits and uncertainties are recorded.

Decide and label

• The decision rule (the limit for each test that ends the shelf life) was set before the results came in, and the shelf life is the shortest time any limit is reached, with a safety margin that is written down.
• The date on the label matches the study result, the storage instruction on the label matches the study conditions, and an 'after opening' instruction is given where the study showed it is needed.
• The study report is signed, filed with the product specification, and linked to the HACCP plan where shelf life is a control.
• The study is repeated or reviewed when the recipe, process, packaging, supplier or distribution chain changes, and on a schedule for long-life products.