Homemade Yogurt

The most important concern with yogurt is to maintain a constant incubation temperature of about 110ºF (43ºC). This is the temperature that those friendly bacteria become the most active. There are several ways to do this depending on the season and where you live in the world.

Simply use as much milk as you want yogurt. I generally like to make a couple large jars as I use yogurt for many things-primarily a morning fruit smoothie to keep the bacterial garden in my intestines growing in a healthy manner.

Generally, I measure the milk into the jar intended for incubating and then pour this into a pan, and heat.

If you are using fresh raw milk it is best to not allow the temperature go too far above 110ºF unless you are trying to kill any bacteria in the milk. Enzymes start to die off at a temperature of 108ºF. I like to heat my raw milk to about 120ºF. At this temperature I use a little more yogurt culture and allow the yogurt to incubate longer than 8 hours. Experiment, and find out what works best for you with the conditions you are bound by.

Yogurt made from fresh raw milk that is not first scalded and then allowed to cool may have different textures than yogurt most of us are accustomed to.

In order to get the creamy texture of yogurt the milk should be heated gently to 180ºF and allowed to cool. This will provide a clean slate for the yogurt cultures to take over and colonize. If it is milk that is pasteurized and homogenized it is better to let it come to a boil and then cool down to around 110-115ºF, before adding the culture.

One method for checking the temperature that my mother taught me was to put your finger in it and see if you can hold it for ten seconds. The results should be…counting 1, 2, 3,…9,10, ouch!

Unfortunately, it seems my years as a chef have killed some of my sensitivity to heat in my fingers. I was constantly killing the bacteria in the yogurt using this method and had to resort to a thermometer for a while until I recognized the correct temperature with my finger again.

Once the milk is heated you only need to add about a tablespoon of yogurt per 4 cups (or one litre) of milk. The best way to do this is to temper the yogurt with a little warm milk before adding it into the jar.

Also prepare the jars by keeping them full of hot or warm water before adding the milk and yogurt to them.

If you have a warm spot in your home all you need to do is to wrap up the yogurt in a towel and keep it overnight in that spot.

Other Methods for Incubation
I found making an incubator over our heating vent was an excellent place to make yogurt in the winter. In the summer all I have to do is wrap up the warmed jars of yogurt in towels and leave them overnight. In the spring and fall it is more complicated and I have to resort to using our cooler filled with hot water. You have to be careful with this operation. Depending on the size of the cooler, how many bottles of yogurt you are making it is important to get the warmth of the water in the cooler hot but not too hot. I like to have the water about half way up the jars of yogurt. Another way to do this might be to put water into a hot water bottle and add it to the cooler. I generally add more hot water to the cooler after a few hours with this method to make sure the temperature remains warm enough.

Yogurt cultures do not like to be moved much or shaken as they are growing.

Yogurt needs about 8 hours to complete growing although it won’t hurt it if it is longer than this. The longer the yogurt is incubated the more sour it will become, if there is too much yogurt culture in the milk it will come out more sour as well.

The more sour the yogurt the more a lactose intolerant person will enjoy the yogurt as lactose is converted into lactic acid by the lactobacilli.

More info about yogurt and live cultured foods:
Wild Fermentation by Sandor Ellix Katz
To Heat or Not To Heat: A Yogurt Question by Mother Linda
Cream Cheese and Whey Video

Meet the goats who provide the milk in this demonstration of different incubation methods: