The expiry date is naturally your best indication. But when you look closer at the stamped date, it actually reads “Sell by”, “Use by” or “Best before” instead. Do they mean the same thing as the expiry date?
No, according to Consumer Reports. The sell-by date is to inform retailers when to take the item off the shelves. But it isn’t the same as the expiry date. Milk, for one, could last five to seven days past its sell-by date before turning sour, said the website.
Meanwhile, the best-before date indicates “how long the food will be at its best quality,” said Goh. For example, chips may not be crispy past this date but the lao hong snack may still be edible. But if you have any doubt, do not eat it even if the food is within the date, she said.
HOW EXPIRY DATES ARE DETERMINED
“The expiry dates of food products are determined by a combination of factors, such as the types of the ingredients used, the manufacturing process, the type of packaging used, and how the food product is stored,” said a spokesperson from the Agri-Food & Veterinary Authority Of Singapore (AVA).
It can be dangerous to eat foods that have passed their use-by dates.
Some food companies commission microbial challenge studies, which deliberately introduce harmful micro-organisms such as Listeria moncytogenes into the food that is being tested, according to Londa Nwadike, assistant professor of Food Safety, Extension Food Safety Specialist at University Of Missouri, Kansas State University.
The contaminated food is kept under conditions that it is likely to encounter during transportation, in storage, in the store and at home – and tested at various lengths of time, wrote Asst Prof Nwadike in her article in The Conversation. This helps to determine the point at which the level of micro-organisms present is too high for safety.
Sometimes, micro-organisms are not added at all, and the test simply monitors the taste, smell, texture and appearance of the food to determine the longest possible time it can be kept without compromising its quality and safety, wrote Asst Prof Nwadike.
Food companies then remove at least several days from this duration to set the use-by date. However, there is no “standard for the length of this safety margin” and the margin is “set at the manufacturer’s discretion”, noted Asst Prof Nwadike.
The testing isn’t a once-off affair either. According to the HACCP Mentor, food manufacturers should submit their food products for retesting every time they introduce new equipment to the manufacturing process, or change the recipe, formulation or even the pack size.
To ensure that the manufacturers – both local and overseas – comply with Singapore’s food safety standards and requirements, the AVA “monitors, inspects and samples” the food products. However, the onus of setting the expiry dates lies with the food manufacturers,” said the spokesperson.
EXTENDING FOOD’S SHELF LIFE
Whether it’s sardines or orange juice, the same tricks are generally used to extend the product's life span: Less moisture and/or more acidity, sugar or salt levels. Sometimes, heat and preservatives such as benzoates are used, too.
As a result, the shelf life of foods such as eggs, bread and milk can be extended from days to months, depending on the food, processing and packaging techniques, said Dr Matthew Zhao, packaging technologist with Singapore Polytechnic’s Food Innovation And Resource Centre.
Even for food products that are still within the expiry dates, if you suspect any spoilage, just discard. Don't risk food poisoning.
Jarred items such as jam, peanut butter and sauces can be extended for months, while juices and stock in tetra packs can last from months to years, he said.
That canned food and convenient frozen bites, including fish balls, fish fingers, crab sticks, nuggets and dumplings, which you stash in the freezer for emergencies? They should be good for a couple of years, said Dr Zhao.
WHAT TO THROW OUT, WHAT TO KEEP
What if the can of fruit cocktail in your larder has just exceeded its expiry date by a mere few days? Seems like a waste to chuck it.
Chances are, you can go ahead and dig in as canned foods can still be eaten a few days after their expiry date, said Toby Amidor, a nutrition expert and author of The Easy 5-Ingredient Healthy Cookbook. That is provided the can looks fine and you have stored it properly in a cool, dry, dark place, he said.
Dairy products such as yoghurt, milk and cheese are generally safe a few days past their sell-by dates, unless you see signs of spoilage, said Amidor. Milk, for instance, is drinkable up to five days past the sell-by date, he said. Cheese, especially the hard varieties, can last a little longer.
Obviously, rusty and/or bloated cans as well as anything that has sprouted mould belong in the bin. Other signs to look out for include badly dented cans; leaking or bulging cans/lids; cracked jars or jars with loose lids, or those that appear to have been opened, said Goh from Mount Elizabeth Novena Hospital.
But what about food such as cereals, chips, biscuits and other foods that have lost their crunch? Is it still ok to eat them if they are just a little after their expiry dates? The rule of thumb: If the packaging’s appearance is different from the norm, or it has an unusual odour after opening, do not eat its contents.
Still undecided? You're better off skipping food you're not sure of, said Goh. “Even when it comes to food products that are still within the expiry dates, if you suspect any spoilage, just discard. Don't risk food poisoning,” she said.
For a second opinion on how long a food stays safe to eat, you can check the free app created by the US Department Of Agriculture.
What if you only realise the food has passed its expiry date after eating it? Wait and see if there are any symptoms, said Dr Reuben Wong, gastroenterologist from Gleneagles Hospital. These would include diarrhoea, vomiting and/or fever. You should seek medical help immediately if you do.
“The body has a defense system in the form of strong acid in the stomach that will help kill incoming germs. It is believed that taking activated carbon or probiotics might help, but there is no firm evidence that this would prevent food poisoning per se," he said.
