Thursday, June 25, 2009

Do consumers understand “Use-by” and “Best-before” dates?

I think that many consumers don't understand these package marks.

I recently received a message from a very distressed reader. She'll recognise herself, but I'm sure she won't mind my writing this.

The reader had a 16-month-old son and had fed him a jar of organic apple, pear, blueberry and blackberry with vitamin C. The young man had eaten it all and was apparently bouncing around, as 16-month-olds tend to do. The jar and contents appeared normal, with a suitable vacuum in the headspace.

After the meal was over, the mother looked at the jar and found the “best before date was 29th July 2008!” (her exclamation mark). She went on: “I am very concerned that he could get Botulism from this - is there a way that I could get the remains of the food in the jar tested to make sure that he is not in any danger? Please, I am happy to pay for this and your time.

“I have spoken to a few people and they have all said that we will have to wait the 10 days to be on the safe side. Is there anything else I can do to protect my son? or help to prevent anything really nasty making him sick from this?”

This mother was obviously very frightened. Her concern was triggered by the best before date, which is an advisory to the consumer about quality. Chemical changes can occur slowly in cans or jars of food during storage. These changes may be accelerated if the food is exposed to sunlight or high temperatures. These changes may make the food less appetising, such as giving a "cardboardy" or flat, oxidized taste. The changes are not harmful. If the food is outside the Best Before date, it does not necessarily indicate that it is unsafe to eat, though that might be the case with something like ham or egg salad, which are much more perishable.

I didn’t have any further information on the product, but would expect that it would have been processed either as an acid food (pH less than 4.6) and pasteurised, perhaps hot-filled, or processed as a low acid food (pH above 4.6) and thus be given a 12D process (sterilised). In either case, Clostridium botulinum toxin would not be produced. Any changes occurring after the best before date would be quality deterioration only, not safety issues. There are several other points to come out of this discussion, but I'll cover them in a future posting.

Extrapolating from this, it is probable that consumers and perhaps retailers don’t fully understand the significance of “use-by” dates. I have certainly seen products in supermarket display cabinets with the original “use-by” date covered with a second label bearing a later date. The latter is illegal in New Zealand.*

And the boy? I had a message from his Mum today - this is the 11th day since he ate the food, which had actually been made in 2006. He didn't get sick and is now toddling around the home at high speed. Well, some food stories have happy endings!

* You can find an article "Date Marking - Standard 1.2.5" on the NZFSA website at


Anonymous said...

On many boxes I see the best before dates are in numbers and letters. How do I comprehend this?

John said...

Which country are you in? Will you post an example of the code, please?

Curry Barking Mad said...

Hello John,
This may be a long shot but I make curry sauces without chemical preservatives etc. here in the UK.
I don't know how I would go about getting a Best Before date legally. I assume I can't do my own tests and then put a date on a sticker.
Any advice would be appreciated.

John Brooks said...

Hello Mick
You can indeed do your own tests. Remember, the Best Before date is a recommendation to the consumer about the quality aspects of your product. If you do storage trials and find that your sauces retain their sensory qualities for 14 weeks, then you could put that information on your package. Perhaps give yourself a margin and say "Best before 12 weeks". Beyond that date, your consumers might see some deterioration in colour or flavour etc.
Check the local regulations regarding Use By dates. That tells the consumer not to consume the product after that date and the retailer is not permitted to sell it after that date. In some countries, this date is called "Sell By Date".

John Brooks said...

Further to Mick:
If you think that your products are unstable or could potentially become dangerous, e.g. they are low acid, packed in hermetically sealed containers, like glass or barrier plastic pouches, and not given a 12D process, you should contact a food consultant, such as Campden BRI ( They will be able to advise you and conduct safety tests to establish a Use By date.

Curry Barking Mad said...

Thank you John, a great help.

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