There are lots of sites out there with yogurt recipes. Here’s the one I ended up using:
- At least 1 litre milk (I use whole)
- 1–2 tbsp sugar per litre of milk
- 1/4 cup powdered milk per litre of milk
- 2–3 tbsp starter per litre of milk
- (optional) 1 tbsp vanilla per litre of milk
- Heat milk in a double boiler or in a bowl over a pot of boiling water until it reaches 180F, stirring frequently.
- Remove from heat and let cool (either in an ice bath or just resting) until it reaches 110F (no hotter than 120F and no cooler than 100F), again, stirring frequently (so it cools evenly).
- Pour in remaining ingredients and stir for a solid minute or two to disperse the bacteria throughout.
- Pour the mixture into jars/bottles (I use 250 mL mason jars).
- Place the jars/bottles in a cooler and fill with hot tap water at least half-way up the jar/bottle.
- Close the cooler and let rest for 8–12 hours.
- Put the jars/bottles in a fridge to chill for a few hours and then enjoy!
Yield: 1 gallon (4 litres) of milk gives me exactly 19 250 mL mason jars of yogurt.
- For a starter, either use some yogurt from your last batch or buy a little bit of plain yogurt from the store. Be sure it includes live bacterial cultures, though!
- The longer you let it ferment, the thicker (and more tart) the yogurt will be. (It also thickens as it chills.)
- Be sure to leave the bottles undisturbed during the fermentation period. It’s best not to open the lid or move the cooler once you place it the first time.
- I haven’t tried, but I understand it is difficult to make yogurt set if you put fruit purées in at the beginning. I prefer plain and vanilla yogurt anyway. I usually just add some purée to the yogurt in a bowl and stir it up. (I’m trying dulche de leche yogurt next time. I’ll let you know how it goes!)
- One flavouring technique I’ve read (but not tried) is to put the fruit and the plain yogurt in a blender, re-bottle the yogurt, and let it chill. They say it will set at least a little.