How to Make Yogurt in a Lab

Yogurt starts with an active bacteria culture and milk.

Yogurt isn't just a tasty, calcium-rich treat or part of a refreshing parfait. It's also an interesting lesson in science. This fermented milk product actually contains a ton of bacteria, giving yogurt its signature sharp flavor and smell. These bacteria help break down food in your stomach and intestines, aiding and toning your digestive system.

Creating yogurt in a lab not only demonstrates how bacteria and fermentation work, it also gives the students a rewarding treat when the lab is finished.

Things You'll Need

• 1 pint low-fat or skim milk
• Small saucepan
• Spoon
• Candy thermometer
• 4 ounces plain, live-culture yogurt
• Glass mason jar
• Heavy towels

Instructions

1. Heat a pint of low-fat or skim milk in a small saucepan over medium heat, stirring it every few minutes with a spoon. Warm the milk until your candy thermometer reads 160 degrees Fahrenheit.

2. Turn the heat to medium-low, letting the milk cool down to 110 degrees. Heating the milk this way kills bad bacteria that may cause it to spoil before your yogurt is ready.

3. Scoop 4 ounces of plain, active culture yogurt into a large mason jar. Using yogurt to make yogurt may seem redundant, but you need the live bacteria to create your own yogurt starter culture.

4. Pour just enough warm milk over the yogurt to cover it. Stir the yogurt into the milk with a spoon; this is your starter culture.

5. Add the rest of the warm milk to the jar and cap it tightly. Wrap the jar with heavy towels and let it sit for 12 hours. You should be able to easily scoop the gelled milk, now yogurt, from the jar with a spoon.

References

• Yucky Fun and Games: Make Your Own Yogurt
• Makezine: Jeff Potter's Yogurt Lab
• Probiotics- Love that Bug: How to Make Probiotic Yogurt