Most people think yogurt is made by illegally employed underage fairies somewhere in the deep forests of mainland China. I’m sorry to shatter their idyllic dream but that’s as true as a speed measurement result from an Italian neutrino detection lab.
All you need to make yogurt at home is milk and a starter culture from the bacteria. If it’s difficult to find a starter culture, you can use natural live yogurt from a store. Guessing which types of yogurt on the market contain live bacteria can be hard but most likely they would be brands that are marketed as “natural”, “plain” or “simple”, and without additives like fruits and sugar.
Boil the milk, then leave it to cool to about 40-45 degrees C, which is the optimal temperature at which the bacteria will start to ferment it. You can use a cooking thermometer to determine the temperature or alternatively you can try the classical method of my Balkan forefathers, who used to dip their pinky in the milk and count to 15. If you can endure the hotness of the milk without removing your finger until you finish counting, everything is set. If you can keep your finger longer than that, the milk should be slightly heated again. If it hurts and you’re forced take it out earlier, it needs further cooling.
For 1 liter of milk you need about a table spoon or two of yogurt. Stir the yogurt well until it becomes a homogeneous paste and then mix it with the warm milk. Pour the mixture in a container and wrap it with a cloth that will keep it warm for the next 4 hours. Alternatively, you can put the container in a large pot with a little bit of warm water around it and cover everything with a lid, so the heat loss would be minimal. After 4 hours the yogurt should be ready and you can put the container in the fridge.
Your first attempt may not produce ideal results but that shouldn’t prevent you from trying again. You should also remember that what you’re making is real yogurt – its texture and taste may be different from the one sold on the market because commercially produced yogurt usually has a lot of additives that “improve” its consistency, for example milk powder or cream. By making it at home, you’re getting rid of them and what’s left is a product which is much healthier.
If you intend to continue making your own yogurt at home, it would be a really good idea if you use a table spoon from your previous batch as a starter for the new one. That way each time you’ll end up with higher content of live bacteria and that will improve the consistency and texture.
“Live” yogurt secretes lactic acid, which is a yellowish liquid that forms around the edges of the container. Its presence shouldn’t be alarming, right the opposite, it’s a sign of a job well done. However, if there’s too much of it, it may be an indication that you overheated the milk.
The type of milk you use matters a lot as well. I would advise you to use whole milk. The difference between 4% and 1% fat content is not that much, so whoever told you you’re going to lose weight by consuming skimmed milk lied. You will loose much more weight by removing sweeteners from your diet instead of tiny insignificant amounts of milk fat.
Last but definitely not least – some people with poor knowledge of biology freak out every time they hear the word “bacteria”. This is not only unnecessary, it’s downright stupid. I’ve seen recipes for yogurt online in which people are advised to keep sterile conditions as if they are going to perform a surgery. Don’t get paranoid about it, just maintain the usual hygiene necessary for handling any other food products and use clean utensils, pots and jars. I come from the Balkans where yogurt is a staple food and we have the highest yogurt consumption per capita on the planet. Trust me, my great-grandmother didn’t use aseptic surgical gloves, just soap and water.