The Yogurt Lid Doesn't Always Mean an Expiry Date

Tomorrow, open a sealed yogurt that has stayed refrigerated and look at the date it carries. That figure may indicate safety, or merely signal until when it keeps its best quality. To decide properly, you also have to read the words printed next to the number.

Spain did not officially change the yogurt date in 2022. Until 2013, this food's quality standard required a use-by date set 28 days after production. Royal Decree 176/2013, passed in March of that year, removed that fixed term and let each manufacturer determine the appropriate date and how to express it under European rules.

The legal change opened a gradual transition. Companies had to review their products, their storage and the information they offered. Some kept the old formula for a while; others adopted the best-before date. In January 2022, Danone, Spain's largest yogurt maker, announced it would apply the latter to its brands. The news traveled widely and ended up being confused with a regulatory reform that had happened nine years earlier.

The practical difference fits in two sentences. A use-by date is used on highly perishable foods that may pose a risk beyond the stated limit; once passed, the product should not be eaten. A best-before date signals until when the expected qualities hold if the container is stored as instructed; going past it allows you to assess the product, but does not by itself guarantee it is still fit.

Two milks show the contrast without leaving the same food family. Fresh pasteurized milk carries a use-by date because its refrigerated life is short. UHT milk, treated at a higher temperature and packaged to last for months unopened, carries a best-before date. Both are called milk, but the treatment forces you to read different dates.

Something similar happens with yogurt. Its fermentation, its acidity, the container and refrigeration all influence how long it lasts, but they do not authorize a universal rule of so many days or weeks. What you can do with a specific pot depends on the label, on whether it is still sealed, on the temperature it has kept and on any further instruction from the manufacturer.

AESAN, Spain's food safety agency, recommends that a properly stored product past its best-before date be examined before being thrown away. The sequence is to look, smell and, if nothing seems wrong, taste a tiny amount. It is guidance for that kind of date, not an invitation to ignore a use-by date, nor a promise that every yogurt lasts the same.

The check starts with the container. An abnormally bulging lid, a leak, a broken seal or a damaged pot are reasons to discard it. Once opened, mold, a strange color or a smell clearly different from the product's usual one also mean the bin. Faced with a doubtful sign, there is no need to taste anything to confirm it.

A little whey on the surface does not belong on that list. The yellowish liquid can separate naturally from the solid part of the yogurt during storage. It can be stirred back in and, by itself, does not indicate spoilage. Nor is it enough to call any smell sour: yogurt is already an acidic food and each variety has its own aroma.

The absence of visible signs is not an absolute guarantee either. That is why the kind of date, the instructions and the cold chain matter before resorting to the senses. A food past its use-by date is discarded even if it looks normal. With a best-before date, observation only works within the conditions for which the manufacturer calculated its life.

The phrase "keep refrigerated" is part of that decision. A yogurt that has spent many hours out of the fridge does not recover its intended condition when put back in. The number on the lid was calculated for a specific treatment throughout its commercial life. If that treatment is broken, a still-distant date does not make up for the change.

The instruction that follows opening also rules. A container can carry a far-off best-before date and at the same time order that, once opened, it be finished within a few days. From the moment the lid comes off, air, utensils and microorganisms from the surroundings come in. The specific after-opening term then becomes the applicable reference.

AESAN's campaigns around 2022 sought precisely to stop consumers from reading every number the same way. The coincidence with Danone's announcement put yogurt in the spotlight, but the explanation covered the whole shopping basket. Rice, pasta, dried pulses and many frozen products usually show a best-before date; minced meat, fresh fish and certain chilled dishes carry a use-by date.

Eggs add a particular case. Their minimum durability date is set at 28 days from laying. The coincidence with yogurt's old 28 days can mislead, though it comes from different rules. Counting days without identifying the food or reading the full wording turns two different labels into one false common instruction.

The problem reaches a considerable scale. Eurostat estimated that the European Union generated some 59 million tonnes of food waste in 2021, around 131 kilos per inhabitant. The European Commission further calculates that up to 10% of food waste may be linked to misreading what the dates mean.

That includes food discarded automatically upon reaching its best-quality date. It also includes the opposite risk: treating a use-by date as a flexible suggestion because the container still looks fine.

In 2020, EFSA published technical guidance to help operators decide which date belongs on each food. Its decision tree weighs factors such as the treatment applied, the possibility of recontamination, storage conditions and how microorganisms behave over shelf life. The words on the lid come out of that analysis.

A manufacturer can also change the date when a recipe, a process, a container or the intended temperature changes. That is why one brand's track record should not be transferred to all the others. That a previous yogurt kept its qualities well past a certain number of days sets no reusable term for another product.

Tomorrow, in front of the fridge, ask the yogurt the three prior questions: has it always been kept cold? Is it still sealed and undamaged? Is there a special instruction on the side? With a use-by date passed there is no further route: it goes in the bin even if it looks perfect. With a best-before date passed and those conditions respected, apply AESAN's guideline — look at it, smell it and taste a tip — and decide from what you find, without trusting the memory of another pot that lasted longer.