Science and Our Food Supply: Investigating Food Safety from Farm to Table

SAFETY 

FIRST

• 

NEVER DRINK ANY JUICE USED IN THE LAB. 

• 

Wash hands thoroughly before and after the lab. 

• 

Disinfect all lab surfaces before and after working in the lab 

(see page 8). 

• 

Wear safety gloves. 

• 

Seal inoculated Petri dishes using Parafilm (see page 8). 

• 

Remind students never to open a dish with organisms 

growing in it. Some organisms could be dangerous  

pathogens. 

• 

After the lab is completed, discard all disposable dishes 

using safe techniques (see page 7). 

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MIDDLE LEVEL

ADVANCE PREPARATION

• 

Do some juice “scouting” and find pasteurized and unpasteurized juice 

made from the same type of fruit. (If available, unpasteurized apple cider and 

pasteurized apple juice work well.) 

• 

If unpasteurized juice is not available, you can prepare your own (see below). 

• 

Use 2 pint jars or other clear containers that have lids. Wash and sterilize the 

jars and lids (see page 8). 

• 

Mark one container “A,” and pour in 1 to 2 cups of the unpasteurized juice. 

Close the lid. 

• 

Mark the other container “B,” and pour in 1 to 2 cups of the pasteurized 

juice. Close the lid. 

• 

Keep the containers closed and refrigerated until class time.

• 

On activity day, place the equipment that students might use on a lab table.

 

GETTING STARTED

MATERIALS

For the Class 

• 

Pasteurized and unpasteurized juice  

(1 to 2 cups of each) in clear containers 

For Each Team 

• 

2 to 4 sterile Petri dishes with nutrient 

agar and covers 

• 

Sterile swabs 

• 

Parafilm to seal dishes 

• 

Safety gloves 

MYSTERY JUICE