As soon as the yogurt hits 112*F, I will add culture. You can get culture several ways. You can purchase it from a yogurt supply company, which can be a bit tedious and pricey. I prefer to just use a yogurt from the store. My role of thumb is more bacterial strains = better. This is one I like:
I have a strainer set up to strain the yogurt before putting it into jars. If you skip this step, you will have lumpy yogurt.
Now the yogurt is at 114*F, and I will mix in the yogurt culture. I am adding one 5 oz container. Then I pour the yogurt culture mix through the strainer and pour into warmed mason jars.
I pack the space with a towel. The temp of the yogurt is now at 110*F and will remain in the closed “incubator” for 12 hours.
Since it is currently 4:30 pm, I’ll take it out at 5 in the morning. You must be careful about what time you start your yogurt. I have had get up at 3 am on occasion to put the yogurt in the fridge.
Tomorrow we will have fresh, delicious, full fat (a cream line even) yogurt to eat. You should try some. Although I’ll warn you: