- Cool box (and optional blanket and polystyrene board for added insulation)
- Sealable glass containers (avoid narrow opening and bare metal !)
- Large, heavy-bottom saucepan (to prevent milk burning at the bottom)
- 2 or 3 big heaped tbs (i.e. 1 big heaped tb per litre of milk) of natural yoghurt
- 2 to 3 L of milk (qty depends on the size of your containers) (I have always used semi skimmed milk so cannot comment on other types)
- 2 or 3 heaped tbs powdered milk (it makes it creamier), (i.e. 1 heaped tb per litre of milk)
- 1/2 tp salt (otherwise it tastes pretty bland.)
- 1 tb sugar (to help the bacteria grow)
Important note: I based my recipe on a simple scientific rule: yogurt-making bacteria will not multiply below 33˚C and will die above 55˚C.
First, find enough sealable containers.
Work out how much milk you need. If you don’t know how much your jars contain, work it out as follows: fill a container with water and weigh it (not including the weight of the pot of course!) then convert into ml, i.e. if it says 500g, count as 500ml of milk. Add all the other measurements together to know how much milk you will need to use in total.
Heat up the milk (with the sugar and salt) until it reaches 85˚C (you will notice some frothing appearing on the top)
While the milk is cooling down, start preparing the rest:
- take the yogurt pot out of the fridge to warm to room temperature.
- Sterilise your glass containers: wash with hot, soapy water and rinse. Place upside down on a grill in a cold oven. Switch oven at 150˚C. When the temperature has been reached, i.e. the little orange light disappears (~10mn), switch off the oven and leave the containers in there until required.
- Pour boiling water over the lids and leave to drain.
- Put hot water in the cool box to start warming it up (about 4 or 5 kettles worth). You will want it to be just below 55˚C by the time you place the containers inside it).
- Optional: Put hot water in a jug. My saucepan does not pour very well, so I pour the yogurt mixture into a jug (and above the sink!) and then use the jug to fill the containers so that it is not too messy a job.
- Put the yogurt into a mug, add powdered milk and mix. When the milk temperature has dropped below 55˚C, add milk slowly and stir until you get an evenly mixed and liquidish consistency (the cup should be about 3/4 full unlike the picture below that was taken a bit too early).
- Take the containers out of the oven (they should still be hot but not burning to the touch). Pour milk into the jug then fill containers (Tip: fill the jars to the top otherwise the excess air will make them float and topple over when you place them inside the cool box) If the lids are still wet, dry them with a paper towel. Tighten lids and place jars inside the cool box (you might need to add some cold water first if still too hot)
Tip: Although the thermometer in the picture above reads “43”, I now use water at just under 55 degree Celsius.
Wait 7 to 8 hours. I make my yogurt in the evening and leave it to do its magic overnight. Tip: place a thick blanket over the cool box and stand it on top of a polystyrene board to retain heat for as long as possible. The following day, take containers out of the cool box and place in fridge to chill. Sealed pots should easily keep 2 to 3 weeks.
P.S. Delicious with Maple syrup! Yum!
Below is what 3 litres of yogurt looks like:
You can also notice that I now use different pots as the ones I used originially started to rust…