Making your own yogurt is very easy and the final product is delicious. You can use the type of milk you want — from full cream milk to skimmed milk, and even soy milk if you wish to go vegan. And what more is: with a bit of practice you can get exactly the tanginess you want by adjusting the fermentation time (and to a certain extend, the temperature).
Strictly speaking, yogurt is milk cultured with the lactic acid bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Milk cultured with other lactobacilli or bifidobacteria have other names, e.g., acidophilus. For the sake of ease, I will refer to both types as “yogurt” unless we're talking about real yogurt, in which case I will use the term “yogurt proper”.
The effective time for making a batch of yogurt is around half an hour. However, heating and cooling the milk takes time, so does the fermentation and the final “maturing”: Starting one day before noon, the yogurt is ready for consumption the next morning.
- 1 L milk (cow's, goat's, soy)
- 1 dL starter culture
Make sure your hands and utensils are impeccably clean!
Heat the milk to 85°C in order to denature the proteins. If this step is omitted, the final yogurt tend to separate into curd and whey. If you overdo the temperature significantly, the final product will have a faint taste of boiled milk.
Let the hot milk cool to 41°C if you wish to make yogurt proper, or around 37°C for other cultures.
Mix in starter culture. If you haven't made yogurt before, buy some unsweetened, unflavoured, and unpasteurized yogurt, otherwise use some yogurt from a previous batch. Alternatively, use one or two probiotic capsules (you can easily separate the gelatine capsules and use the freeze dried culture inside).
Cover with a lid and let the mixture sit at the required temperature (41°C for yogurt proper, 37°C otherwise) for 6-8 hours. The longer the fermentation, the more tangy the final product will be. If you're using soymilk, the fermentation will take approximately 50% longer: 9-12 hours.
Place the yogurt in the fridge and let it set for 12+ hours before using it.
Set aside some yogurt for your next batch before adding fruits or flavouring.
We're culturing bacteria here, so keep your hands and utensils clean at all times!
You can heat the milk in the microwave oven. When my microwave operates at full power, it takes 2×5 minutes to reach 85°C if the milk is taken from the fridge, and 2×4 minutes when the milk has room temperature (e.g., soymilk that hasn't been refrigerated). If you plan on making yogurt regularly, knowing your microwave can be a real timesaver.
A good yogurt machine that holds one litre cost €25-30 and is totally worth it. Otherwise it can be difficult to keep a stable temperature for a prolonged time. These yogurt machines almost always come with one setting only, 41°C, which is too warm for other cultures than yogurt proper. To solve this problem, connect the yogurt machine to a plug-in timer of the type that has a dip-switch for every 15 minutes. Switching the machine on and off for 15 minutes at a time keeps the temperature at an average 36-37°C, which is just perfect for other cultures.