Six weeks past the date stamped on the lid, a bag of red lentils sits at the back of the shelf. Bin it and you have wasted food along with the money that bought it. Use it and you risk… what, exactly? The answer depends entirely on which date you are reading.

In the UK, a use-by date is a safety instruction. A best-before date is a quality forecast. Most of what lives in your pantry carries the second kind, which means the date on the packet is a comment on flavour and texture rather than a warning about illness. Judging whether those lentils are still worth cooking takes about thirty seconds, a decent nose and a willingness to look properly.

What the two dates actually mean

Use-by dates appear on food that can become unsafe quickly: chilled meat, fresh fish, dairy, ready-to-eat salads and the like. After that date the food should not be eaten, cooked or frozen, and shops cannot legally sell it. That is not retailer caution; it is food law.

Best-before dates work differently. They are used where safety is not the issue, so you will find them on dried pasta, rice, flour, oats, tinned goods, oils, spices, sugar and salt. Once the date passes, the food may lose aroma, texture or bite — but it does not become dangerous on a particular Tuesday. Shops may legally sell food after its best-before date provided it is still fit to eat.

You may also see display until or sell by printed on packaging. These are stock notes for shop staff and mean nothing to you at home. They have largely disappeared from UK shelves, but a few older packets still carry them.

Why dry pantry food rarely carries a use-by date

Because spoilage bacteria and mould need water. Dried pasta, rice, lentils, flour, sugar and salt hold too little moisture for the microbes that make people ill to get going, so there is no safety deadline to print. What does change over time is fat and aroma. Oils oxidise, which is what rancidity is: a stale, crayon-like smell and a flat, slightly soapy taste. Anything with its natural oils intact — wholemeal flour, brown rice, oats, nuts, seeds — turns noticeably faster than its refined cousins. Think months rather than years for those.

The two-minute test before anything goes in the bin

1. Read the label first. Use-by means the end. Best-before means it is your call.
2. Smell it. Rancid fat smells of old crayons, putty or paint. Stale spices smell of dust. Fresh lentils smell faintly earthy; tired ones smell of very little.
3. Look for mould. On dry, porous foods — flour, bread, nuts, grains — mould threads run deeper than the patch you can see, so bin the lot rather than scooping out the top layer.
4. Check for pests. Fine webbing, clumped flour, small moths or grains with tiny holes mean pantry moth or weevils. A light infestation can sometimes be salvaged by freezing and sifting; a heavy one is not worth the effort.
5. Examine tins and jars. Bulging, leaking, rusted or badly dented cans are a hard no, as is a jar lid that has lost its seal.
6. Taste a pinch — only if the first five checks have passed, and only for low-risk dry things such as spices, herbs or a flake of cereal. If it tastes flat or soapy, replace it.

What genuinely outlives its date by years

• Salt, sugar, honey and plain dried pasta: effectively indefinite when kept dry and sealed. Crystallised honey is not spoiled; stand the jar in warm water and it loosens up.
• White rice and dried pulses: good for years, though very old beans and chickpeas stay stubbornly hard however long you soak them. Use those in slow-cooked soups or grind them for fritters.
• Tinned beans, tomatoes and sweetcorn: several years, though acidic tomatoes dull in flavour. A tin well past its date that looks and smells normal is usually fine.
• Ground spices and dried herbs: they lose their punch long before they become a problem. Use more, or replace them.
• Baking powder: test half a teaspoon in a cup of hot water. A good fizz means it will still lift a cake.

When the label wins and the food goes out

A bulging tin goes in the bin, unopened. That swelling can indicate bacterial spoilage, and it is not something to investigate by taste. The same applies to anything with a use-by date, food that has clearly been damp — flour that has clumped and smells sour — nuts or oils that taste bitter, and jars whose seals have failed. If you are pregnant, elderly, very young or living with a weakened immune system, hold a stricter line: nothing past a use-by date, and bin anything past its best-before that you are unsure about. If you become unwell after eating something questionable, speak to a pharmacist or your GP.

Storing the pantry so dates matter less

Dates assume ideal conditions. Your cupboard is probably warmer and damper than the pack designer imagined, especially if it sits next to the oven or above the fridge. A few habits make a real difference:

• Keep goods cool, dark and dry, and away from the hob.
• Decant into airtight jars, and write the best-before date on the jar with a marker. Keep the original packet if it carries allergen or cooking information.
• Freeze new arrivals of flour, rice, oats and dried fruit for a few days to kill any moth eggs before they hatch.
• Buy small quantities of the things that fade quickly: ground spices, nut flours, seeds, wholemeal flour.
• Run a "use first" shelf at the front. Anything within a month of its date goes there, and you cook from it before opening a fresh bag.

A simple habit to keep the shelf moving

Treat a best-before date as information rather than an instruction. Read it, then check the food itself: smell, look, and taste a little if it passes muster. Most of the time the lentils are fine and dinner gets made. When they are not, you have learned something useful about what you actually get through in a month — which is the only reliable way to stop buying the same unloved bag of pearl barley twice a year. Compost what fails the test where your council collects food waste, and let the rest earn its place on the hob.

Photo: PublicDomainPictures / Pixabay