I've never bothered with sterilisation to a great deal (just hand washing with washing-up liquid), I just use UHT milk (I think it tastes better for yogurt, and

I've never bothered with sterilisation to a great deal (just hand washing with washing-up liquid), I just use UHT milk (I think it tastes better for yogurt, and it's already obviously more sterile than fresh milk). I just add a spoonful of yogurt to 1-2 L of milk (I don't bother heating it beforehand), leave it in my PID-controlled crock pot [1] overnight at about 42°C, then it's done. I usually leave the yogurt in some coffee filters for an hour or two to get more of the whey out and make the yogurt thicker. If you leave it for 2-3 hours it's essentially solid, and absolutely delicious. [1] No write-up yet I'm afraid, but it's a custom PCB I made with a simple temperature sensor, Atmel microcontroller and mains relay that switches on and off my crock pot. It's powered from the mains via a cheap board-mount switch-mode power supply, so no extra power required. Board files here: https://github.com/SeanDS/slow-cooker/tree/master/hardware/v2 https://github.com/SeanDS/slow-cooker/tree/master/hardware/v....