Yoghurt is basically milk fermented with a specific strain of bacteria (usually Lactobacillus acidophilus and Streptococcus thermophilis), that turns the lactose into lactic acid and so the milk into yoghurt.
This is a simple process in theory, milk is just heated to a warmish temperature, the starter bacteria culture added, and its left at a constant temperature for the bacteria to do their thing.
In practice, it might be simple, but there are lots of slightly different ways of doing it.
How I discovered this method
I’d been wanted to start making my own cheese for a while, and yoghurt making seemed the 101 place to start to get the hang of the very basics (ie it has three main steps in the process, instead of fifteen).
So I looked online for how to make it, and then got very confused by the millions of recipes and methods people used.
Some used powdered yoghurt strains, some used frozen, some mixed in milk powder, some used hospital levels of cleanliness with consistent results, some didn’t. Some people heated their milk, others didn’t.
Then there was keeping it warm – some kept it warm in the oven, others wrapped towels around it, put them on heating pads or hot water bottles, and yet others were put in a cosy bath in an esky and topped up with hot water.
Then there’s what seems to be the most popular method, a brand name set up called the Easi-yo. I’ve heard they work pretty well, but I wanted to try it without buying specialised equipment, thermometers or sachets etc (and I couldn’t find an Easi-yo for less than $30). So I combined bits of all the recipes to find the easiest way for me to make it.
Which starter to use
I use Jalna Biodynamic as my starter. I bought a 200g container of their yoghurt for about 4 dollars, and froze it up in ice cube trays to keep as a starter.
Some people say you can’t use frozen starter and its needs to be fresh each time, but it works for me. I think cleanliness comes into it – ie don’t handle the cubes with your fingers.
One jar of starter makes enough starter for me for about 10 batches of yoghurt, so it works out pretty economically. I worked out that it costs about $1.50 for the milk, 40 cents for the starter and 50c for the powdered milk, so you get a litre for less than $2.50, and you know exactly what is in it.
- 1 litre milk
- 5 tablespoons of powdered milk
- 2 tablespoons of fresh yoghurt (or roughly 4 ice cubes of frozen yoghurt starter)
- Boiling water
- Double boiler (or a mixing bowl over a saucepan containing boiling water)
- Measuring jug (for pouring milk into the thermos)
- Thermos (preferably wide-mouthed)
- Towel (to wrap the thermos)
- Take out the starter to defrost on a saucer if you’re using frozen starter.
- Fill the thermos with boiling water to sterilise it and pre-warm it.
- Use some boiling water to pour over the jug, and any saucers or utensils you’re using. Set them aside in a clean spot.
- Mix the milk and powdered milk. This is optional but I do it because I like thick yoghurt and it increases the calcium content. You can also use gelatine apparently.
- Put it over the double boiler. You can heat it directly but this way you don’t have to stir it constantly or worry about it burning, just check it occasionally.
- Heat it up to near boiling – ie once the milk starts steaming and collecting bubbles around the edges.
- Take the saucepan off the heat for a few seconds so you don’t burn your fingers with steam and transfer the bowl to the sink.
- Let it sit for 20 minutes or so to cool down. The technical temperate is 41 – 48 degrees C, but ‘comfortably warm’ is the non-technical temperature and the one I use. Just check the bowl now and then until it feels nice and warm – not uncomfortably hot or cold.
- Don’t worry too much if it cools down too much while you’re watching tv – just heat it back up again and let cool to the right temperature.
- Pour a bit of your warm milk into the measuring jug and add the starter. Mix well without frothing it up too much to get rid of any lumps.
- If using frozen starter – drain off the excess water from the starter – don’t mix it in.
- Pour the yoghurt-y milk into the rest of the milk. Mix well.
- Pour into the thermos to a level below the seal and close it up. Don’t let it touch the seal, they’re hard to clean and if it has any mould it will affect the yoghurt.
- Wrap it in a towel and leave it in a quiet spot without disturbing it for 6 – 12 hours. Times vary a bit depending on the temperature you added your starter – if it’s on the cool side it will take longer – and the amount of starter you used – if you use more it won’t take as long.
- You can tell if it’s done by the feel – it will have a more solid feel in the thermos.
- After that time it should be set. Scrape or pour it out of your thermos depending on thickness (if you bought a wide-mouth this will be much easier!) and put it into the fridge to chill. It will get a little bit firmer once it cools down as well.
That’s it. It’s a simple process but can take a bit of experimentation to find out how much starter you need balanced with the right amount of time and right taste.
Possible Problems in Yoghurt Making
Onto possible problems you might encounter with yoghurt making. The two major problems that I’ve found to cause failures are the lack of cleanliness and old starter.
This is because what you’re really doing with all this heating, cooling, and keeping warm is providing the right environment for the culture of the yoghurt bacteria to breed for a few hours – and not any other bacteria strain.
Cleanliness is REALLY important, as you don’t want to breed other strains of nastier bacteria in there with your lactobacillus. If you do, you get runny yoghurt or strange tasting yoghurt.
As for old starter – yoghurt usually only lives for ten days or so, so if your batch is old it isn’t going to work. You can also only use the same strain a few times before it gets contaminated, meaning you can only make yoghurt from your yoghurt a few times before you need fresh starter.
Leaving it too long can cause issues too – it will get too tangy with some strains, the whey will start to separate, or with the Jalna, which doesn’t have as strong a taste, will just form small chunky bits instead of being a really nice smooth thickness like custard.
Uses For Yoghurt
If you’re keen and have heaps of yoghurt, you can also make a yoghurt ‘cheese’ called Labneh, which is used a bit in Middle Eastern dishes and can be a dip or dessert or cream replacement.
All you need to do is have a fairly thick yoghurt and then draining it in cheesecloth over a bowl (to catch the whey).
This isn’t really like cheese in my opinion, but more of a heavy-cream with a yoghurt flavour and less of a fatty taste. It’s absolutely delicious with desserts and I’d guess a lot better for you than real cream.
Though you do lose a lot of the weight of the yoghurt in the whey (the liquid that drains out) and it makes a surprisingly small amount of cheese.
Anyway, there are a million ways to make yoghurt; this is just mine. Feel free to experiment and tweak the method to whatever suits your equipment and taste.
Other People’s Ways to Make Yoghurt (Or Yogurt)