Freezing Food Before Its Use-By Date: What a Virologist Explains

Anyone who has done a big shop will recognise the situation: the fridge is full, everyday life is hectic, and suddenly the critical date on the packet is looming. Chicken breast, mince or salmon fillets are then quickly put in the freezer. A virologist explains when this last-minute move is still acceptable, where the real risks lie, and why handling dates on packaging correctly remains essential.

What really happens when food is frozen shortly before its date

Océane Sorel, a virologist known in specialist circles for her work on viruses and micro-organisms, takes a matter-of-fact view of spontaneous “last-minute freezing”. In principle, a properly chilled product that has not changed can still be frozen on the day before its use-by date – and sometimes even on the date itself.

“Freezing only temporarily stops bacteria. They do not die; they simply pause.”

Sorel uses an easy-to-remember comparison: freezing works like the pause button on a remote control. Most germs stop multiplying, but they remain present. Once the food is thawed, the film starts playing again, and the bacteria resume where they left off.

That is the crucial point. If a product is only frozen after it has already spent many days in the fridge, the number of germs that has built up over that time is frozen along with it. When thawed, this “community of microbes” becomes active again and can continue to spread. This is not necessarily serious for healthy people, but it does increase the likelihood of stomach and bowel problems.

Use-by and best-before dates: the confusing labels on packs

Before reaching for the freezer, it is important to understand which date is actually shown on the label. In everyday life, many foods are thrown away unnecessarily because the distinction is unclear.

Use-by date: this is where the line is drawn

The wording “use by …” identifies particularly perishable foods. These include, among other things:

• Fresh meat products, including mince, steaks and poultry portions
• Fresh fish and seafood
• Fresh dairy products, such as certain desserts or raw-milk products
• Chilled ready meals with a short shelf life

Once this date has passed, the product is considered potentially risky. Experts take a clear position: if the use-by date has expired, the food should neither be eaten nor frozen. Even if it still smells fine, invisible germs may already have reached levels that can cause unpleasant consequences.

Best-before date: a matter of quality, not safety

“Best before …” belongs to a different category. It mainly applies to long-life products such as:

• Pasta, rice and flour
• Tinned food and food in jars
• Chocolate, biscuits and crisps
• Dried pulses, coffee and tea

After this date, flavour, texture or colour may deteriorate slightly, yet the food is often still perfectly suitable to eat. Many consumers dispose of these products because they are unsure. Studies show that enormous quantities of edible food end up in the bin because of this confusion: a loss of quality is mistaken for a health risk.

Last chance for the freezer: when “late” can still be safe

Health authorities advise freezing meat and fish as soon as possible after buying them if it is clear they will not be cooked promptly. Anyone who only acts at the last moment should inspect the product more carefully.

A checklist for an emergency freezer decision

Before putting a product into the freezer on the day before its use-by date, it is worth carrying out a quick safety check:

• Visual check: There should be no discolouration, slimy film or unusual coating.
• Smell test: Does it smell neutral or as expected? Musty or sharp odours are a clear warning sign.
• Packaging: Is it still sealed, with no tears or swollen areas?
• Chilled chain: Was the food refrigerated quickly after purchase, rather than left in a warm car for a long time?
• Fridge temperature: Ideally, this should remain consistently at around 4 °C or below.

“Anyone freezing food late should check twice that the product still appears to be in perfect condition.”

If there is any doubt, it is better not to put the food in the freezer and to throw it away instead, however painful that may be financially.

How long can frozen food be kept?

Once a product has been safely placed in the freezer, time works differently. At -18 °C, bacteria remain dormant, although quality and flavour gradually change. Useful household guidelines include:

Food	Recommended time in the freezer
Red meat, such as steak or a roasting joint	6–12 months
Poultry	6–8 months
Mince	3–4 months
Fish	3–6 months
Ready meals and stews	2–3 months
Bread and baked goods	1–3 months

These periods relate to quality rather than a strict safety limit. Writing the freezing date on the packaging with a pen makes it easier to keep track and prevents packs from disappearing among ice crystals for years.

Thawing food properly: where most mistakes happen

How food is thawed is at least as important as when it was frozen. This is when bacteria regain their advantage. Specialists recommend:

• Thaw food in the fridge, ideally on the bottom shelf in a bowl.
• Alternatively, use the microwave defrost setting immediately before cooking.
• Never thaw food at room temperature on the kitchen worktop.
• Do not reuse thawing liquid; pour it away.

Thawed food should be cooked promptly and eaten soon afterwards. One rule is particularly strict: food that has already been thawed should not be returned to the freezer, especially if it was already close to its use-by date before being frozen for the first time.

Reducing food waste without risking your health

The main challenge arises in everyday life: nobody wants to throw food away unnecessarily, but nobody wants to experiment with spoiled mince either. A sensible approach to using the fridge can help achieve both aims.

It makes sense to plan roughly while shopping: what will be eaten today, what tomorrow, and what is unlikely to be used? Products intended for later are best frozen as soon as they have been unpacked. Saving food on the day before its use-by date should then be the exception rather than the routine.

Useful practical measures include:

• A clearly visible “eat soon” section at the front of the fridge.
• Freezing small portions rather than large blocks, so everything freezes through completely and thaws more quickly later.
• Planning meals two or three days ahead instead of playing unplanned fridge Tetris.

Why children, pregnant people and older adults need to be especially careful

People with a robust immune system often cope with minor lapses in food hygiene without serious consequences. For some groups, however, the situation is different: pregnant people, young children, older adults and people with chronic conditions are considerably more sensitive to germs in food.

In these households, it is worth paying particularly close attention to dates and storage conditions. When in doubt, it is better to use the freezer earlier – or to decide against late freezing and shop more cautiously next time.

Anyone who understands the basic principles – reading dates correctly, freezing in good time and thawing hygienically – gains much more freedom in the kitchen. The freezer then becomes not a last-minute stopgap, but a well-planned tool for reducing food waste without putting personal health at risk.