I made a batch of homemade yogurt. It is nearly finished.
The necessary ingredients are two tablespoons of fresh plain, unflavored yogurt that has just been opened, and one quart of whole milk. Don’t use skim milk. Skim milk might work, but will be an inferior product after culturing.
I made my yogurt using the haybox method. Since I don’t have a haybox I used a cooler instead of a haybox. They both work on the same principle of insulation trapping in the heat.
Here are the steps I followed:
1. Heat milk to 180 degrees F.
2. Skim the skin off the top of the milk.
3. Pour the milk into mason jar.
4. Put lid tightly on mason jar.
5. Set mason jar in cold water bath and bring temperature down to 120 degrees F.
6. Drop two tablespoons of yogurt into the jar.
7. Stir the yogurt into the milk.
8. Heat at least a gallon of water to 115 degrees F.
9. Set the yogurt jar with lid tight, upright in the cooler.
10. Pour the water into the cooler until the cooler fills up about 1 inch below the mouth of the jar.
11. Double check the water temperature with a thermometer. If it is not right around 112-117 Fahrenheit, scoop out some water and add hot or cold water to adjust the temperature range to the sweet spot.
12. Close the lid tight on the cooler.
13. Allow to sit for 5-10 hours.
14. Refrigerate the yogurt when done.
It is a good idea to check the cooler every couple of hours, and if the water has cooled below 110 degrees F. scoop some water out with a cup or jar and add back some hot water, a little bit at a time, until the temperature is back up to 115 degrees.
The yogurt must be kept at or above 110 degrees, up to 115 degrees Fahrenheit. The bacterial cultures thrive and reproduce quickly in this temperature range, preventing milk spoilage.
The longer the yogurt cultures, the tangier the final product will be.
This is a really cheap way to eat all the yogurt you want. Where I live milk is about $3-$3.50 per gallon, so I can make yogurt less than $1 per quart.
You can use your homemade yogurt as the starter for the next batch, so you only need storebought yogurt the first time. Thereafter, just transfer a few tablespoons of yogurt from each batch into a small jar and refrigerate until you need it to start the next run.
Depending on the size of the cooler, many mason jars can be done at once. Next time I may run 6 quarts of yogurt culture at once.