📅 Shelf life

Shelf life is the time during which a product, if stored correctly, stays safe and keeps its quality. In the EU it is shown in two ways: “use by” and “best before”. EU Regulation No 1169/2011 requires a “use by” date on foods that are highly perishable from a microbiological point of view and could quickly become dangerous. After that date the food is deemed unsafe.

The “best before” date is about quality, not safety: after it the food can usually still be eaten, but its taste and texture may decline. For foods that keep for up to 3 months, the day and month are enough; for 3 to 18 months, the month and year; for more than 18 months, the year alone. The producer decides which date to use: in Britain, for example, cheese is usually labelled “best before”.

For milk, shelf life depends above all on processing. Pasteurised milk is heated to at least 72 °C for 15 seconds and has to be kept cold. Ultra-high-temperature (UHT) milk is heated for 2–10 seconds at 135–150 °C and filled into aseptic packaging, so unopened it can be kept without a fridge. Raw milk gets no such treatment and spoils quickly.

Shelf life or expiry date? Shelf life is the period a correctly stored product stays safe and keeps its quality, while the date on the pack comes in two kinds: “use by” for safety and “best before” for quality. Use by or best before? The producer decides which one to print, so cheese in Britain, for example, usually carries “best before”. Pasteurised or UHT? Pasteurised milk needs the fridge, unopened UHT milk does not. Raw milk gets no heat treatment and spoils quickly.

The label tells you which date you are looking at: “use by” on highly perishable foods and “best before” on the rest. For up to 3 months a day and month are enough, for 3 to 18 months the month and year, for more than 18 months the year alone. Read it on chilled milk, cheese and yogurt in the dairy aisle of supermarkets and corner shops, and on UHT milk, which sits on ordinary shelves. Follow the storage text, such as “once opened, keep refrigerated”.

Why it matters to you. A “use by” date only holds under the conditions stated on the label: your fridge should be set to 0–5 °C, and if the pack says “once opened, keep refrigerated”, store the product at 5 °C or below. You can freeze it up to the end of the day shown in the date: at −18 °C bacteria do not grow, and once defrosted the food should be used within 24 hours. After a “best before” date, judge the food by its look, taste and smell, for example whether dairy products have gone sour.