Making yogurt without a machine is very easy if you accept a slight degree of unpredictability, as yogurt cultures can be temperamental. The tricky part is keeping the yogurt at the right temperature while it sets, and this is where a yogurt maker helps, but it’s by no means indispensable (I don’t own one and I have been making yogurt for years).
Like many people interested in making yogurt at home, I knew it was easy – theoretically. But it wasn’t until I witnessed it that I realized how ridiculously simple it really is. The main steps are very straightforward: heat milk – let cool – stir in a spoonful yogurt - let set; but of course, the devil is in details.
Step 1: Scald milk
In a saucepan, heat milk until bubbles begin to form. Remove from heat.
Step 2: Let milk cool to just above body temperature
Yogurt cultures are most active just above body temperature, at 110°F (43°C). A good way to gauge the temperature without a thermometer (I don’t own one, either) is to place your little finger in the milk and count to 10. It should feel warm but not burn. If the milk is too hot it will kill the yogurt cultures. If it is too cold the yogurt will take forever to set or not set at all.
Step 3: Stir in 1 tablespoon “starter” yogurt per quart (liter) milk
Any commercial plain yogurt works, as long as it contains live cultures (specified in the ingredients).
Using more “starter” yogurt will not help, on the contrary. Think of it as overcrowding; too many live cultures make the yogurt thinner and more sour.
Stir well so the starter yogurt dissolves into the milk.
Step 4: Pour milk into container(s)
Any container will do, large or small, jar, bowl, storage container, etc.
Preheat container(s) with hot water to maintain as much heat as possible. Cover with lid, cloth, or parchment paper (this makes a difference; left uncovered the yogurt doesn’t set as well).
Step 5: Let set in a warm place
The temperature should stay as close as possible to 110°F (43°C). This is the tricky part, the one for which the yogurt maker was invented, but there are a number of other ways to maintain heat. I have tried the following methods, they all work, it’s a question of choosing the one most practical for you:
- Place containers in a cooler bag (space permitting, add a bottle of hot water to maintain heat)
- Wrap a towel around the containers and place in the warmest place in the house
- Preheat oven to 200°F (90°C), turn off oven (very important!), and place yogurt containers in the preheated oven. (Don’t forget the yogurt and accidentally turn the oven on for another use. I must admit it has happened to me. More than once…)
Do not disturb the yogurt until it is set – anywhere from 3 to 12 hours. (It happens that the yogurt doesn’t set, in that case the same milk can be reheated to repeat the process.)
Yogurt keeps in the refrigerator for weeks.