Use-by dates on food
Did you know the use-by date on food isn't valid once you've opened the packet?
Up to 500 Kiwis fall ill with a food-borne illness every day. Knowing what to watch out for and ensuring you don’t contaminate food you’re preparing can help you avoid food poisoning.
Our tips will help you keep your family safe from food-borne illness.
Use-by and best-before dates
Packaged foods with a shelf life of less than two years must have a label showing the use-by or best-before date.
Use-by dates are about food safety. The date’s determined by the time required for the pathogens in food to grow to levels above which illness might occur. As long as the food is stored correctly and isn't opened, it should be safe to eat before its use-by date. After the use-by date, a food can't legally be sold and shouldn't be eaten.
Use-by dates usually appear on perishable food like meat, poultry and deli products.
Best-before dates are about food quality. Food can be sold and eaten after its best-before date as long as it’s been stored according to the instructions on the label. But it may have lost quality and some nutritional value.
You'll find best-before dates on less perishable foods such as cereals, flour and canned goods.
As soon as you open any packaging, the shelf life becomes the same as if the product was unpackaged. For example, a packet of vacuum-packed smoked salmon may have a use-by date that’s one month away – but once you’ve opened it, you should keep it in the fridge and eat it within two days (see How long will it last?).
How long will it last?
How long it is safe to keep a particular food depends on many factors: its water and protein content, its freshness and quality when you bought it, the temperature at which it has been stored, the type of pathogens likely to grow on the food, and your immune status.
Also, use-by dates should be treated with caution if you are pregnant or have lowered immunity due to illness or medical treatment.
Always take note of the use-by date and storage instructions if there are any. As a general guide, here's how long you can keep food in your fridge once the packaging is opened.
|Product||How long it lasts|
|Smoked salmon||2 days|
|Smoked chicken||3 days|
|Cooked chicken||2 days|
|Pasta sauce||2 days|
|Long-life milk||3 to 10 days, depending on brand|
|Camembert or brie||1 week|
|Cottage cheese||5 days|
|Cream cheese||2 weeks|
|Sour cream||1 week|
|Soy milk||5 days|
|Tomato sauce||8 weeks|
|Sliced ham||5 days|
|Canned fish||2 days|
|Mayonnaise (store-bought)||8 weeks|
|Pickles and chutney||8 weeks|
|Canned baked beans||3 days|
|Canned whole peeled tomatoes||3 days|
- Always wash and dry your hands thoroughly before and after preparing food.
- Use separate cloths for wiping hands and dishes – and make sure they’re clean.
- Use different coloured cloths for the dishes, the bench and the floor – ideally, use paper towels to wipe up floor spills.
- Change your dishcloth regularly. For a quick fix, rinse well then microwave it for 2 to 4 minutes on high … that’ll kill most of the bugs.
- Keep raw and cooked foods separate at all times.
- After cutting raw meat and poultry, wash your chopping board and your knives thoroughly in hot soapy water or in the dishwasher.
- Use separate chopping boards for raw food and food that’s not going to be cooked before eating (such as salads).
- Cook chicken, mince and sausages right through. If in doubt, the best way to tell is to use a meat thermometer to check these meats are cooked to the safe internal temperature of 75°C.
- Marinate food in the fridge – and cook the marinade before pouring it over cooked food.
- Make sure your fridge temperature stays in the safe zone between 2°C and 4°C.
- Cover food before putting in the fridge.
- Always cover raw meat and store on the bottom shelf of the fridge so that juices don’t drip on other food.
- Freezers should be between -15°C and -18°C but food is safe as long as it is frozen solid. Anything that defrosts should be cooked, refrigerated or eaten within two hours. If in doubt, throw it out.
- Defrost food in a covered container in the fridge overnight or on the defrost setting in the microwave. Make sure it’s defrosted right through before cooking.
- Perishable food can be left covered at room temperature for up to two hours. Then it should be eaten, refrigerated or thrown out.
Another important factor in food safety is how it's stored in your fridge. Here are the basic rules:
- Keep your fridge between 2 and 4 degrees Celsius. Older fridges frequently run at higher temperatures. You can check the temperature with a fridge thermometer, available from hardware stores.
- Replace poor door seals - they stop a fridge from maintaining its temperature.
- Don't jam in the food. Air should be able to circulate, to maintain an even temperature.
- Keep raw meat in the chiller or on the bottom shelf, separate from other raw and ready-to-eat foods.
- Defrost food in the fridge, not on the bench. Avoid thaw drips getting onto other foods.
- Keep foods in the fridge covered with cling film or in containers with watertight lids.
- Throw out refrigerated leftovers after two days unless they've been frozen. Once thawed, frozen leftovers should also be thrown out after two days.
- Keep your fridge clean.
- Choose products with informative labels that list storage instructions. Look for products with the longest use-by dates.
- Never taste food that looks or smells strange. If in doubt, throw it out.
- Buy food in quantities appropriate to your household usage. If you live alone, buy small packages to avoid lengthy storage, or divide perishable food into small portions and freeze for later use.
- If you get sick, take to your bed and drink plenty of fluids. Water is fine, but rehydrating fluids like sports drinks may be better: you're trying to make up for the fluids lost in the diarrhoea. See your doctor if the symptoms are severe or persist beyond a couple of days. Babies and small children with severe diarrhoea should always be taken to a doctor. If you think you know which food made you sick inform your local public health service.