The first time I ate yoghurt was at the age of 9 or so, at a friend's house. My parents couldn't abide the stuff so there was never any in the house. My mom had always said it was disgusting, so when I finally got around to eating some, I was pleasantly surprised. I think it may have been grape flavored. But then I forgot all about it.
The second time I ate yoghurt was in Year 8 science lab. We did an experiment in bacterial cultures. Unfortunately, due to the class schedule, it stayed in the incubator for 3 whole days and by the time we opened it up, it had gone halfway to cheese. By that time I had so little memory of what yoghurt was supposed to taste like that I didn't even realize that anything was amiss until my Australian lab partner turned her nose up at it.
That episode left me with the impression that you needed all kinds of equipment to make yoghurt. Where was I supposed to get an incubator, or powdered bacteria? I don't even have a cooking thermometer. Today, I found out that all you need is a cup of store-bought yoghurt (one that says it's got live cultures), and a bucket. Or preferably a beer cooler.
First you need to sterilize a jar. And then, you need to sterilize your milk. Bring it up to boiling point, stirring frequently, and then let it cool down to a hot but not scalding temperature.
Wikihow says that the ideal temperature for culturing yoghurt is between 90 degrees F (32C) and 120F (49C). Since the human body is at around 98F (37C), that's about the temperature of hot bath water.
Then you add the pre-bought yoghurt, just 2 tablespoons of it, and then pour the mixture into your sterilized jar. Seal it, then dunk it in a beer cooler or bucket of hot bath water for 4-12 hours. Change the water whenever it starts getting cool.
I covered my bucket with aluminum foil (shinier side down) and wrapped it in several dish towels to keep it warm for longer.
When the yoghurt has solidified, pour off the excess liquid (whey), flavour it, stir, and put it in the fridge. I just added a teaspoon of sugar. Next time I might experiment with little fruit chunks. And the awesome thing about it is that it's self-perpetuating. I can use this batch to start off the next one!
I think I'm going to have some for breakfast tomorrow morning. The little spoonful I tasted seemed all right. Here's hoping that it doesn't make me ill.
My Boyfriend's buddy, who's Indian, says that his family doesn't even bother to incubate the yoghurt. They just leave the jar in the fridge overnight and eventually it yoghurtifies. I'll have to see if this really works. From what I remember of biology, the cold of a fridge doesn't kill bacteria, it just slows it down. So maybe if you leave it long enough, you'll still get yoghurt. Perhaps his family likes their yoghurt on the watery side for cooking? He says he grew up on yoghurt poured over rice. Some people are lactose intolerant; this guy's lactose dependent. He gets ill when he doesn't eat dairy products.