CNA Explains: Should you throw away food that is past the 'best before' date?
How are date marks on prepacked food decided and how do you tell if food past such dates is still edible? CNA talks to a nutritionist, food science expert and manufacturer.
SINGAPORE: If you are confused about the multitude of date marks on food packaging and what they mean, you are not alone.
Believing that these "expiry" dates are the be-all and end-all, consumers often bin edible food that has gone past the dates.
At the same time, a movement to reduce such food waste is emerging in the form of food rescuers and social enterprises that redistribute food to people willing to look past these dates.
In December last year, CNA trailed one family that collected and gave away packaged food such as popcorn, coffee powder, pudding and oat milk – all past best-before dates.
More recently, a social enterprise aimed at reducing food waste gave away food past date marks ahead of its closure in February. The enterprise, known as MoNo, aims to change consumer mindsets on food past their best-before dates that are still safe for consumption.
But is such food truly safe to consume? If yes, why the date marks?
CNA spoke to a food science expert, a manufacturer and a nutritionist on the differences between the date marks, how they are formulated, how they should be interpreted and whether food items past date marks can be consumed.
What do date marks mean officially?
Under Singapore's Sale of Food Act, these are dates permanently marked on prepacked food signifying the expiry date of that item.
Expiry date in this case means that food – when kept under storage conditions instructed – may not "retain its normal wholesomeness, nature, substance and quality" past the date.
This can be labelled as "use by", "best before", "expiry date" or "sell by". It is illegal to sell food that has passed these dates, according to the Singapore Food Agency's website.
What's the difference between "use by", "best before", "expiry date"?
“Use by" dates are stricter than other date markings as they can refer to the safety of the food, particularly for infant formula, or fresh produce like meat, fish and poultry, a Singapore Institute of Technology associate professor said.
"These items should, as much as possible, be consumed by the dates indicated as they tend to turn bad, spoil or (become) rancid at a quicker rate than other types of food," said Dr Siti Noorbaiyah Abdul Malek, an expert in food safety and quality.
“Best before” dates, on the other hand, indicate how long food will last before it starts to lose its quality.
"For instance, a packet of biscuits may be found soft instead of crisp after the indicated 'best before' date, but they can still (be) edible," Dr Siti said.
But this is provided that the food was stored properly, under the right temperature and environment, she added.
The Singapore Food Manufacturers' Association said a "best before" date is akin to a recommendation based on the manufacturer's experience. After the date, the food could still be edible but might have lost its texture or flavour.
"Expire by" and "use by" date marks can be taken as "hard deadlines", after which a product might be contaminated, said the association's IT director Ang Khim Whee, who also sits in Enterprise Singapore’s Food Standards Committee and the National Codex Committee.
How do manufacturers determine such dates?
Through lab tests, experts said. According to Mr Ang, the lab will test five different parameters, including total plate count and escherichia coli (E. coli) bacteria.
Total plate count measures the bacteria count of the product over time, said Mr Ang. A small sample of the product is diluted, then placed in a petri dish and tested.
Dr Siti said manufacturers may also conduct shelf-life studies on products through a real-time or accelerated approach. For real-time testing, manufacturers keep food at storage conditions specified on their label and evaluate the food intermittently to see how it has deteriorated throughout the study.
"When the extent of deterioration has compromised the quality of the food ... they can then indicate the shelf life of the food,” she said.
In the accelerated approach, manufacturers keep food at elevated temperatures to speed up deterioration.
"Similarly, once they determine that the quality of the food has been compromised, they can extrapolate the shelf life based on certain mathematical models that can be used to predict results."
Food manufacturers usually choose "best before" dates conservatively well before the time food would spoil and become inedible, Dr Siti said.
So can food past "best before" dates be eaten?
In a nutshell, yes – but at your own risk. Using your senses to judge whether a product has gone bad is key, experts said.
They advised to visually check if anything is growing on the product in addition to using your sense of smell and taste.
"Food that is spoiled ... sometimes (during) the earlier phase you may taste alcoholic, acidic or bitter notes," said accredited nutritionist Chan Joy Seng.
The director of Alive Nutrition Consultancy pointed out that food could undergo physical, chemical and microbiological spoilage, all of which could manifest visually.
Chemical spoilage is when chemical reactions occur to spoil the food. Whether such food can still be eaten depends on the kind of chemical spoilage.
“Some of them could be just affecting appearance, taste and texture. Some of them could have long-term health effects, (like the) oxidation of oil (rancidity), even though we may not get direct food poisoning from it,” he said.
Microbiological spoilage is caused by the growth of microorganisms on the product, such as mould, bacteria and yeast. Consuming such food may result in food poisoning.
There is a chance that the food has not changed in appearance but has already gone bad.
"So that's why sometimes it's actually quite difficult to assess. For example milk ... so if you actually put it in the fridge for a long time and it's gone beyond expiry date, it could still look the same without any significant change in flavour at the beginning," said Mr Chan.
"But there could still be micro-organisms that ... grow to spoil and change the flavour of the product. For example, lactic acid bacteria present will ferment and produce acids that cause milk to curdle and also have a sour taste."
As such, Mr Chan does not recommend that people consume food past expiry dates.
Dr Siti said that in such cases, consumers may refer to credible websites that provide databases of food storage guidelines, such as the United States government's food safety website.
Does food beyond "best before" dates still have nutritional value?
Mr Chan said that for plant produce, nutrients usually degrade slower than the product's appearance.
"So even for fresh produce that may look quite dry and start to wrinkle ... while they could have some nutrient loss compared to really fresh ones, it's still not as great of a decrease compared to the differences in appearance," the nutritionist said.
The most sensitive nutrients for foods are generally vitamins, with vitamins C and B more sensitive to heat and oxidation. Minerals, carbohydrates and proteins are more stable.
"Vitamins are usually sensitive ... minerals are all the way at the other end, even if you throw something in the furnace, burn it into ash, the minerals are still there," said Mr Chan.