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| Lunch box survey
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So what did the NSW Food Authority do?
The Food Authority’s scientists thought it would be interesting to see just how warm lunch boxes without frozen poppers or ice blocks can get on a warm summer’s day compared to those with ice blocks or frozen poppers.
Just like parents across NSW do every school morning, our scientists made up a range of sandwiches. They then packed them into identical lunch boxes.
They made sure some boxes had a “temperature control device”, which is just a fancy term our microbiologists use for a frozen popper or ice brick!
Our scientists also used lunch boxes that didn’t have poppers or ice blocks, while some sandwiches went into nothing more elaborate than a brown paper bag. No temperature control device there!
This way they could compare all three to find which was best at keeping food cool.
Time and temperature are important factors behind bacterial growth. Kid’s lunches can sit in school bags for up to five hours from when the food is prepared to when it’s eaten at lunch.
We all know kids often leave their school bags outside the class room, so we left our sammies outside in a shady spot on a day when the temperature reached 25 degrees.
One of the Authority’s Food-Borne Illness investigators took careful temperature readings each hour for five hours. These were then plotted on a graph, which you’ll find below.
Our science team then sent all the sandwiches off to the lab to see how many food germs were growing. We’ll get to that shortly.
What did the lab find?
Our graph clearly shows how the sammies in the paper bag were up to 12 degrees warmer than the lunch box with a frozen drink. The lunch box with an ice block did pretty well, while the lunch box without a frozen popper or block wasn’t much cooler than the paper bag.
You’ll notice there were bacteria in the sandwiches first thing in the morning, after they were freshly made. There’s no need to worry, as nearly all food has some bacteria present and is still safe to eat.
In fact most bacteria are harmless. It’s only when certain types of bacteria grow and multiply that we can become sick.
You’ll see there were lots more bacteria in the sandwiches in the paper bag and lunch box without a frozen popper or block than in the lunch boxes with the frozen block and popper.
What can we learn from all this measuring?
Simple! The warmer it is, and the longer food stays warm, the more bacteria grow. If there are disease causing bacteria present they might grow too and that’s bad news as they can potentially make us sick.
What are kids actually taking to school?
We also looked at the type of lunch box kids take to school.
Our Food Authority Lunch Box Survey examined the lunch boxes of 598 children aged four to 12-years-old at schools across Sydney.
Teachers were provided with a “School Lunch Box Survey” form and asked students if they had a frozen drink or ice block in their lunch box and if they had foods that needed to be kept cool.
We found ...
| Common Lunch box contents | Numbers |
|---|---|
| Number of children with a frozen drink or ice brick: | 68 |
| Number of children with sandwiches for lunch: | 159 |
| Number of children with sandwiches with meat, fish, chicken or cheese: | 92 |
The Food Authority would like to thank the following schools for participating in our survey:
- Cambridge Gardens Public School
- Kenthurst Public School
- Lindfield East Public School
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