We eat a lot of yogurt in our home, and so when our friend Mathieu taught us a cheap way to make our own we were all ears. You can buy yogurt culture in most health food stores, but do the math and it works out to be only slightly cheaper than buying the yogurt available in those same stores (which is probably not a coincidence). Buy the culture wholesale, and the price drops to about 1¢/litre, meaning your yogurt is basically the same cost as the equivalent volume of milk (generally around half the price of yogurt where I live).
We buy yogurt culture online from Glengarry Cheesemaking in Ontario. The trickiest part is learning how much yogurt culture to add. Glengarry sells the culture in packages of 60 grams, which they say does 60 gallons (~230 litres), and you’re supposed to use ¼ tsp per 3-4 gallons (12-15 litres) for a “small” batch, which works out to about 1 gram per litre of milk. I don’t have a scale that accurate, so I just do it by eye on the tip of a butterknife. After a few tries you’ll get a sense of how to do it, too. If the yogurt is too thin, use more culture; if too thick, use less. If it doesn’t work at all, you probably added the yogurt culture when the milk was too hot.
Method 1: Stovetop
You’ll need a thermometer capable of reading temperatures from 40°C to 85°C, and a large thermos able to contain the jar you want to make yogurt in with lots of room left over.
- Heat milk to at least 85°C
- Allow to cool to 40°C and 45°C
- Pour into glass jar and stir in small amount of yogurt culture
- Place glass jar into a large thermos filled with water at 45°C
- Let sit 4-7 hours (without moving or shaking the container), or overnight
Method 2: Electric Pressure Cooker
After years of making yogurt on the stove, we bought ourselves an Instant Pot model with a yogurt making option, which makes this process even simpler. I wouldn’t buy one just to make yogurt (there are much cheaper options for that) but if you’re buying one anyways and eat lots of yogurt I’d definitely suggest getting a model with this feature. No thermometer or thermos is needed with this method.
You need to use a mason jar since they’re made to withstand heat. Find one that fits inside your instant pot. If you have to squish the lid down, you’ll place too much pressure on the jar and it might break (that happened to me once). I use an old 1 quart jar (smaller than the new 1 litre jars) and bent the steaming rack slightly so that it would fit. Don’t open the pressure regular either; that causes the jar to cool down too fast, which will also break it. Just let the pot cool until the pressure is released (about 20 to 30 minutes).
- Place steaming rack and 2 cups of water into the instant pot
- Fill a mason jar up to the ring underneath the threads with milk, and firmly screw on a lid
- Place mason jar into the instant pot and set to “Steam” for 1 minute with the regulator on the lid set to “seal”
- When cycle completes, turn the pot off, and wait until it cools down to room pressure (the “natural release” method)
- Remove the jar, and wait for the milk to cool to under 45°C, either by using a thermometer or by waiting until the jar is no longer warm to the touch
- Stir in small amount of yogurt culture and seal the jar again
- Place jar in the instant pot (no need for the steaming rack or any water)
- Set to “Yogurt”, and let sit 4-7 hours (without moving or shaking the pot), or overnight