This is the veranda outside in the sun where the class put their bags(and lunches) for the whole day.

SCIENCE FAIR 2009 Another winning science fair project. What were the factors making her school lunch taste so awful? 10 year old Kimberley Fenton demonstrates you are never too young to think like a scientist...

My problem

In the summer (mostly) I have found that the bags on the outside hooks at my school are getting way too hot for too long. People’s sandwiches were going soggy, yogurts turning sour and parents were coming in complaining. I understand that the temperature that bad bacteria grow in is called, ‘The Danger Zone’. Food stored for a long time in the Danger Zone can cause food poisoning. I wanted to find out what was making my lunch go off when I had my bag stored outside the classroom on the hooks.

Aim

Method

I used a sensor system called RIGEL which was programmed to act as a thermometer. The thermometer was tested against mercury thermometers and was accurate to 1 degree. I plugged in two temperature sensors and put one in my lunch box and the other outside my bag to measure the air temperature.

Later on I added an infra-red heat sensor as I noticed that when my hand was in the direct sunlight it was the sunlight that had all the heat in it. The final experiments use three sensors:

• An Infra-red heat sensor outside my school bag
• A Temperature sensor outside my school bag
• A second Temperature sensor in my lunchbox

I took readings all day from about 8:30am to around 3:30pm every ten seconds.

The sensors collected about 2,500 readings each day.

I did my experiments in December, February & March as these are the hottest months of the school year.

Once my data collecting was finished for the day, I plugged the sensors into a desktop computer and all the readings were uploaded into Microsoft Excel.

I then used the Chart wizard to display the data in a line graph. I also used Excel to work out the maximum, minimum, and average temperatures.

Results

Maximum Temperature 75oC Minimum Temperature 15oC Average Temperature 30oC

I found out that our lunches were being kept in the Danger Zone (between 15 - 45oC) for a few hours a day!

I then needed to know what was causing the heat. So I put, just sticking out of my bag, an infra-red light sensor. Infra-red is a type of heat energy. I noticed that the heat inside my lunchbox followed the Infra-red heat energy better than the outside air measurements.

I found out that it was the direct sun light that was making the heat so intense. The heat from the outside air and the lunchbox sort of follows the pattern that the infra-red makes.

I discovered that while the outside air did warm up the lunch box, it was the infra-red heat energy from being in the direct sunlight that had the greatest affect on the temperature of the lunchbox. My food was in the Danger Zone for quite a few hours.

Discussion

I noticed that in the summer my school lunch had gotten to a rather high temperature, whereas in the winter, I had never had a problem like this.

Also, now my bag is in a Cloak bay, I can take sandwiches, cake, or even yogurts to school without them getting soggy or sour.

I think this is because my bag is not in direct sunlight, so it is not getting affected by its infra-red heat energy.

 

My recommendations

I have also found that now I have a Cloak bay, I can take yogurts and sandwiches to school without them getting sour or soggy. Although all of these solutions work, my research recommends putting lunches in the shade or, ideally, a Cloak Bay.

Kimberley Fenton, 10

 

Common Food Poisoning Illnesses

 

Salmonella
Foods involved	Meat, dairy products and salads.
Generation time	20 minutes at 37OC
Main Symptoms	Fever, headache, aching limbs, abdominal pain, nausea, diarrhoea, and sometimes vomiting.

 

Staphylococcus
Foods involved	Meat, diary food, eggs and fish products.
Generation time	30 minutes at 30OC
Main Symptoms	Abdominal pain, severe vomiting, diarrhoea, abdominal cramps, and sometimes collapse.

 

Campylobacter
Foods involved	Meat especially chicken, water and milk.
Generation time	1 hour at 37OC
Main Symptoms	Diarrhoea, abdominal pain, fever, nausea, and vomiting.

 

Listeria
Foods involved	Meat, raw milk, seafood, chicken and vegetables etc (eg coleslaw).
Generation time	1 hour at 30OC
Main Symptoms	Acute/mild fever, influenza-like symptoms.

 

Yersinia
Foods involved	Meat, seafood, water, seafood and raw milk.
Main Symptoms	Under 5 yrs diarrhoea, (sometimes bloody). Over 5yrs abdominal pain (like appendicitis), also fever, joint pain sore throat and rash.
Generation time	1 hour 30 minutes at 37OC