Once you make your own yogurt, it's hard to go back to store-bought. This method is so simple that it will quickly become a regular routine. Once a week I make a quart while waiting for the coffee maker at breakfast, and by bedtime it's ready to refrigerate for the next morning.
I originally started making yogurt as a science experiment with my kids, while we were studying micro-organisms. In order to turn fresh milk into yogurt, you need to introduce acidophilus and other beneficial bacteria. The bacteria ferments the yogurt by converting milk sugar to lactic acid. The milk is heated to kill off bad bacteria and to alter the proteins to give it a better consistency.
To start, you'll need to buy some yogurt to introduce the bacteria into the milk. After that, just save a couple tablespoons of yogurt from your last batch to use in the next batch. In a pinch, I have even used crushed acidophilus pills with good results.
(This recipe appears in my book Edible Inventions from Maker Media.)
Step 1: Ingredients
To make your first batch of yogurt, you will need:
- 2 tablespoons store-bought yogurt
- 3 3/4 cups milk
- a candy thermometer
- a medium-sized saucepan
- a large-sized saucepan
- a quart-sized insulated mug with lid (or other closed container)
- insulated lunch box or bag that can hold the container (or in a pinch, a thick dish towel)
I have found that regular yogurt -- if you can find it -- makes a better starter than Greek yogurt. You will get more consistent results with a big name brand as opposed to an artisanal specialty yogurt
The mug or other container should be as clean and sterile as possible. If it has not been run through a hot dishwasher recently, you may want to fill it with boiling water while you do the other steps.
Step 2: Heat the Milk
Pour the milk into the medium saucepan. Insert the candy thermometer so it sits in the milk without touching the bottom of the pan. Over medium heat, warm the milk until the thermometer reads 180 degrees Fahrenheit. The millk may start to bubble but do not let it boil!
Step 3: Cool the Milk
While the milk is heating, fill the large saucepan with cold water. When the milk has been heated, cool it off by placing the medium saucepan in the large saucepan, being careful not to get any water in the milk. Allow the milk to cool down to 120 degrees Fahrenheit.
Step 4: Add the Starter and Pour the Milk Into the Mug
When the milk has cooled, stir in the starter yogurt and mix well. Then pour the milk into the mug (or other container) and close the top.
Place the milk in the insulated lunch box or bag to keep it warm while the bacteria does its magic. Try not to jostle the yogurt while it's doing its thing, or it may lose its structure and come out runny.
Let sit for 12 hours or until firm. Remove the mug from the lunch box and refrigerate.
Step 5: Open and Enjoy!
Yogurt is great with dried or cut-up fresh fruit and nuts. I usually eat it mixed with muesli-style cereal. For a special treat, I like to serve it over crumbled up muffins with fresh berries on top. It's also great on apple pie or pancakes!
While I prefer my yogurt as is, it's also easy to make Greek style yogurt. Just line a strainer with a coffee filter and scoop some of your finished yogurt into it. Cover with another coffee filter and let sit for a couple hours until most of liquid whey has run out, leaving thickened yogurt behind. Refrigerate.