How to make home-made yoghurt Easy and a whole batch will cost you little more than one small single shop-bought yoghurt.
- Cool box
- Sealable glass containers (not less than 400g otherwise too fiddly and avoid narrow opening! 800g mayonnaise pots are great.)
- Large, heavy-bottom saucepan (to prevent milk burning at the bottom)
- ~1/4 to 1/2 of 150g pot of natural yoghurt (depending on how much milk you use, i.e. about 1 big heaped tb per litre)
- 2 to 3 L of milk (qty depends on the size of your containers – I always use semi skimmed milk so cannot comment on other types)
- 2 heaped tb powdered milk (optional. It is meant to make the yoghurt creamier, i.e. Greek style)
- 1/2 tp salt (otherwise it tastes pretty bland…)
- 1 tb sugar (to help the bacteria grow)
Important note: Yoghurt-making bacteria will not multiply below 33˚C and will die above 55˚C. So, safe working temperatures are roughly 38˚C-50˚C. I like to start work at 50˚C so it gives me plenty of room for manoeuvre. It is amazing how quickly the temperature goes down.
First, find enough sealable containers to fill the bottom of your cool box.
Work out how much milk you need. To do this, weigh one container filled with water (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. Tip: best underestimate quantities as there is nothing more annoying than making too much yoghurt and have nowhere to put it !!!
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 yoghurt pot out of the fridge to warm up.
- 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 & rubber rings (if any) and leave to drain.
- Put hot water in the cool box to start warming it up (you will want it to be between 50˚C and 54˚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 yoghurt mixture into the jug (and next to the sink!) and then use the jug to fill the containers so that it is not too messy a job.
- Put the yoghurt into a mug, add powdered milk and mix. When the milk temperature has dropped to 50˚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. If the lids are still wet, dry them with a paper towel. Tighten lids and place containers inside the cool box (you might need to add some cold water if still too hot)
Tip: If you have a battery-operated thermometer, don’t immerse the whole sensor, just the tip otherwise you might spoil your thermometer like I nearly did the first time I made yoghurt!
Wait 7 to 8 hours. Take containers out of the cool box and leave them out to reach room temperature. Then, place in fridge to chill. Sealed pots should keep 2 to 3 weeks.
P.S. You will need to keep an eye on the temperature inside the cool box (hence the use of a battery-operated thermometer!). If it goes below 38˚C, fill with more hot water. Hopefully, you should only need to do this once.