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How do manufacturers calculate use-by dates on their products?

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Some foods are perfectly safe to eat after their use-by dates, especially if frozen, but there are safety limits for a reason - so how are they calculated?

By Jack Serle

Asked by: Trevor Wooding, Snodland

Use-by dates only apply to perishable products such as dairy foods, vegetables and beer. To determine the dates, samples of the food are monitored in a microbiology lab, in similar packaging and environmental conditions to those of the retail outlet and the home. Food scientists then test the samples for traces of known pathogens. The use-by date is calculated according to the point where levels of the microbes start to exceed safe limits.

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