Make your own yogurt

Like most things homemade, yogurt you make yourself is better for so many reasons:

• It's better for you (no preservatives, sugar or chemicals added) 
• The bacteria are active, so you can be sure that your yogurt has active probiotics 
• It's less expensive 
• It tastes amazing 
• There's no packaging to waste (or to try to find ways to save and reuse) 

Plus, you only need a cooking thermometer and a container with a tightly fitting lid. There's no need to buy any special equipment.

Ingredients:

• 1 Half gallon of milk 
• 2-3 Tbs of plain yogurt (as a starter) 
• 1 8-10 Qt stock pot 
• 1 4-5 Qt pot with lid 
• 1 Metal or plastic spoon (so you can sterilize it) 
• 1 Dial thermometer (it should have a range of at least 100°-185°F, and ideally, a clip for your pot's rim) 

Notes:
However much milk you use, is how much yogurt you will get in return: using 1/2 gal milk gives you 1/2 gal yogurt. You can use regular, reduced or non fat milk, but with nonfat milk, your yogurt will likeky turn out too watery. My sister adds whey protein powder to thicken the fat free milk during cooking and add extra protein.
For your first batch, you will need to purchase plain yogurt with active cultures, like Dannon, Pavels, or Stoneyfield (all future batches you will use your own). Alternatively, you may use freeze-dried yogurt starter cultures.

Step 1-- Make a Double Boiler:
You can skip this step and boil the milk directly in a pot-- but if you do, you have much higher chances to burn the milk on the bottom before it has the chance to heat fully.

1. Create a double boiler by putting the smaller 4-Qt pot inside the larger 8-qt one, and fill the larger one about halfway with water to create a water-jacket effect. 
2. Put a lid on the smaller pot, and heat the water in the big pot (surrounding the smaller pot) until boiling. 
3. Sterilize your thermometer and a tablespoon by putting them in the boiling water for about 15 seconds and removing them. 

Step 2-- Sterilize Your Milk:

• Fill the small pot with milk. Make sure the level of water is at about the same line as the level of milk in the smaller pot. This will ensure the milk is heated evenly. 
• Clip your thermometer to the inside of the milk pot, stir frequently, and wait until the temperature reaches 185F. 
• Once the temperature reaches 185F, remove it from the double boiler and let it cool. 
• Note: The milk will naturally create a type of skin on the top of the milk as its heating and cooling. Try to leave the skin as intact as possible (this skin is like a natural barrier against airborne bacteria from getting inside the milk, so if you don't have a lid on the pot as its heating or while it cools, this layer becomes super helpful)

Step 3-- Cool Your Milk:

• While the milk is heating, you can prepare a cold water bath in your sink using another 8-qt pot or extra large bowl. You may want to add ice to help the cooling process. 
• After the milk has reached 185F, remove it from the boiling water, turn off the heat, and transfer the hot milk to the ice water bath. 
• Keep the thermometer inside, and continue stirring the milk until the temperature reduces to 110F. At this temperature, the bacterial cultures will be able to consume the lactose and grow. 
• Remove the sterile milk from the ice water bath. 

Step 4: Prepare and Add Your Yogurt Culture:

• Prepare your yogurt culture by removing some of your warm, sterile milk and adding it to your yogurt starter to dilute it. This makes the yogurt more watery so it disperses better in the milk. 
• Add your diluted yogurt culture to the pot of 110-degree milk. 
• Stir the yogurt culture and warm milk with your sanitized spoon. 

Step 5: Incubate it and Give it Time:

• Place the lid on the pot, making sure it fits tightly so heat will not escape. 
• Wrap the pot in warm towels to help ensure that the mixture stays a more constant temperature or decreases in temperature more slowly. 
• Place your newly cultured milk in a warm, consistant-temperature area (I use the oven when off and barely warm as the incubator in my house). 
• Hold the pot in this situation for 6-8 hours, or overnight. Refrigerate your finished yogurt for use! 

* to make a second batch, just reserve a small amount of yogurt from this successful batch so you don't need to buy yogurt cultures again from the store.