Introduction: The Fermentation Process of Making Yorgurt

In this Instuctable, you will learn, not only how to make yogurt, but the science behind it!

Step 1: Gather Your Materials.

You will need:

A stove

A sauce pan

A spoon

A kitchen thermometer

Powdered skimmed milk

Whole milk

Live, active yogurt


Step 2: Make Your Mixture!

In a saucepan, add 2 teaspoons of powdered, skimmed milk to 1 pint of whole milk. Whole milk is recommended to make the yogurt turn out thicker then fat reduced milk. Powdered, skimmed milk is recommended to help thicken the yogurt as well.

Step 3: Bring Your Mixture to a Boil Over Medium Heat for 30 Seconds, Stirring Constantly.

This will kill all unwanted bacteria that may be presents.

Step 4: Cool Your Mixture to 46-60 Degrees Celsius!

At this point you should sterilize a spoon and you jar(s) by placing them in boiling water.

Step 5: Place 1-2 Teaspoons of Live & Active Yogurt in Your Milk Mixture!

Stir the mixture well with your sterilized spoon. The live and active cultures found in most yogurts are referring to the live organisms, Lactobacillus bulgaricus and Streptococcus thermophilus.

Step 6: Pour Your Mixture Into the Sterilized Jar(s) and Cover!

Step 7: Incubate Your Mixture for 9-13 Hours!

The temperature should be about 32-43 degrees Celsius. You can try putting your jar(s) in a cooler with other jars of boiling/hot water, personally, I just used my microwave. While your mixture is incubating, the main sugar found in milk, lactose(C12 H22 O11), is being broken down by bacteria and turned into lactic acid(C3 H6 O3). The acid in the mixture now causes it to coagulate/curdle into yogurt.

Step 8: Add Fruits, Nuts, Granola, or Other Flavorings If You'd Like!