Food can be eaten for up to six months after the best-before date and weeks beyond its use-by date, according to consumer watchdogs.
The research also found that ignoring some of the recommendations on best-before and use-by labels could save millions of tonnes of produce from being unnecessarily sent to landfill sites.
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However, while the rules can be bent for some products, those on fresh and processed meat, poultry and fish should not, said Which? Similarly, anyone classed as vulnerable and with underlying health conditions should also adhere to the dates on the labels, it added.
The consumer champions enlisted microbiologist and food safety consultant Dr Slim Dinsdale to look at the best-before or use-by dates on popular products. The government advice is that food is safe to eat past its best-before date but not after a use-by date.
But Dr Dinsdale, of Food Safety Experts, said: "We are far too ready to throw foods away because we go by the use-by date, when, in fact, they're absolutely fine to eat beyond this point.
Dr Dinsdale said eggs could be eaten one week after their best-before date if kept at room temperature and for one month beyond it when refrigerated.
Opened milk can be consumed up to a week after the use-by date for opened or two weeks unopened. Long-life, nut, soya and oat "milks" follow the same rules as cows' milk.
Hard cheese can be eaten three months after the best-before date or until mould growth becomes unacceptable - mould can be sliced off and thrown away. Soft cheese can be consumed up to a week after the use-by date if pasteurised. Those bought in markets or cheesemongers may not be pasteurised so should be eaten by the use-by date.
Butter lasts up to six months, he added, after the best-before date if refrigerated. Low-fat spreads are OK up to two to three weeks after the use-by date.
Fruit and vegetables, meanwhile, can apparently be used for weeks after its purchase if they look fine, albeit with some exceptions. Prepared salads that are unopened should be eaten no more than one week after the use-by date, because of the potential for the growth of listeria. The bits of potatoes which turn green should be cut out because that is the result of the chemical activity of solanine, which is toxic in excess.
Brian Smith, of Booth Smith Food Technology, confirmed that the food industry was cautious when setting use-by dates to protect people, but warned consumers not to take risks with fresh food.
"The food industry bills in a good margin of safety when they carry out their testing on food to give their consumers a safe margin," Smith said. "The guide to the sell-by date is: look at it, but don't be ruled by it. If it looks and tastes bad, it is likely to be bad. But with fresh food or perishables it is best not to exceed the best-before date."