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Study shows lunches can never be too cool for school

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The NSW Food Authority have undertaken a survey which found sandwiches and cut fruit are the main food of choice for school lunches and research has confirmed keeping them cool is key stopping the growth of bacteria.  

The numbers of bacteria in cut watermelon, without an ice brick to keep it cool on a hot day, were 13 times higher by 2pm.  

NSW Food Authority CEO Dr Lisa Szabo said survey results showed the majority of children were showing great food safety behaviours, such as keeping their lunch in the shade or inside (85 per cent) and using insulated lunch bags (63 per cent). 

“Pleasingly 51 per cent of respondents said they used an ice brick or frozen drink to keep their lunch cool – a marked improvement on the Food Authority’s 2009 survey result of 29.3 per cent,” Dr Szabo said.  

“We know time and temperature are critical factors for bacterial growth. The warmer food is, and the longer it stays warm, the more bacteria grow.”  

“The study showed the temperature inside the lunches with the ice brick were six to 10 degrees cooler than those without.  

“Investing in an insulated bag and ice brick – or packing a frozen drink or water bottle – will help keep foods cool and reduce the risk of food poisoning.”  

Sandwiches continued to be the main food of choice for children at 63.5%, followed by cut fruit (5.6%) and pasta (4.9%). About 66% of respondents used a reusable container for the lunch, 14.4% a sandwich bag or plastic wrap and 8.2% a thermal container.  

To view the survey results, visit

Safe school lunch tips  

  • Remember the ideal temperature for bacteria growth is between 5°C and 60°C. 
  • Use insulated lunch boxes or cooler bags and frozen water bottles or drinks to keep lunch cool.   
  • Some food is safe without a cold source, such as whole fruit and vegetables, hard cheeses, meat and fish in cans, bread, crackers, pickles and some spreads.   
  • If lunches are made ahead of time, keep them in the fridge until leaving for school or freeze them in advance.  
  • Ask children to keep packed lunches out of direct sunlight and away from heat sources. A cool, shaded place, like a locker, is better.  


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