Milk power works actually better when making yogurt.

Thank you all for the advises. I see the problem with keeping constant 37C for 8hours. Need some special heater with thermometer. Also the yogurt culture , where you can get that thing? Any ratio suggestions? how much of yogurt culture on 1l or something. Thanks again;-)

.

I think that Chinese (and many foreigners in China) have a healthy tendency to not trust anything that is supposed to come through cold chain, even if it is sold to consumers from cold storage.

Chinese do not really consume as much milk as some other people. They too feed it to babies though, and given the above mentioned risks (combined with other issues surrounding babies in China), they use almost exclusively powdered formula.

As for acquiring fresh milk, when our Chinese neighbour's son was a bit older (todddler), they arranged a mailbox-looking container on the wall outside their apartment, into which they had (supposedly) fresh milk delivered daily or so. I don't know what company provided this service, or whether it's fake or not.

I have good results from this supplier which has several different cultures. If you buy several pouches (each of 10 files each for 500ml to 1 l) you can get a free yogurt maker as well which has a build in timer and temperature control.

chaoshi.detail.tmall.com/[...]

Keeping a constant temperature is what a yogurt machine does. Basically it acts like an incubator for the bacteria. The temperature is not critical, as bacteria will breed as soon as they start to warm up, the warmer it is the faster they breed, until you get to about 47 degrees C, when the heat starts to kill them.
I also use pre-packed cultures, which is basically in a dried powder form and comes in sachets. I use one sachet for each 1 Liter batch.

Thanks guys for the tips. Definitely will check the yogurt machine with those pouches.
I went to Metro today, no imported natural yogurt, but got a Chinese one which says "0% sugar". To my surprise , it is real one. No sugar and tastes naturally, but price tag is not much natural - almost 29kuai for 135g
so can't wait to make mine much cheaper ;-)

thanks again!

One note here; some yoghurts are pasteurised or sterilised after fermentation in order to give them a longer shelf life. Because the bacterial cultures in them have been killed these yogurts are not suitable to use as your starter culture. Most imported yoghurts are sterilised and therefore unsuitable as starter culture.
A lot of recipes in China for yoghurt tell you to add sugar. There is of course no need for this. In general the cultures you can buy in China are of the mild acidic type because that is what is preferred here and since yoghurt is mainly given to children they tend to be too sweet. If you like more acidic yoghurt then apart from leaving out the sugar you can let them ferment a bit longer which tends to make them more acidic. Using previously made batches over and over again as starter culture usually results in more acidic yoghurt as well.

@Alexez I now have an Instant Pot, which has a yogurt setting. But I also used to have pretty good luck with rice cooker: add milk and turn on "keep warm" setting for 20 or 30 minutes. Add culture (I use unsweetened, unpasteurized yogurt purchased from Salvador's), close the rice cooker, unplug it, and cover it with some towels or an old blanket for insulation.

I think the "keep warm" setting itself may be too hot, hence just bringing it up to heat and then trapping the heat in there. It doesn't have to be at exactly 37 degrees the whole time.

With the current temperatures, it works perhaps without machine, just may take a bit longer. Wrap a blanket around. Thermos also will do. Guess this is how our grandmothers did it anyway... :)

I recently run out of culture, so I bought a flavoured yogurt from a Kunming convenience store, it also worked.