Yoghurt making

[Bugs]

I am a newy to this forum but my daughter and I have been making yoghurt in our Thermie regularly, at least twice a week for over 4 years without a failure BUT the last three my daughter has made have not set, can anyone please throw a light on the problem?? We use the similar recipe, I do 800mls full cream milk, 50grms powdered milk, heat at 90 for 10 mins., cool until 37 add 3 tablespoon of previous yoghurt 'cook' for 10 mins at 37 allow to set in easiyo equipment (prewarmed) for at least 6 hours and always sets perfectly, my daughter does almost the same except she has NEVER included powdered milk but she heats at 90 for 20 mins, the rest the same as mine, until the last three no dramas HELP please

[judydawn]

Hi Bugs, welcome to the forum. I don't make a lot of yoghurt, in fact I've only made a couple of batches in 7 years but I'm just wondering if your DD is still using a previous batch of her home made yoghurt as the starter. If she is, it may be time to start afresh with a new starter. Find  the most natural, pot-set yoghurt you can find and give it another go.

[cookie1]

Greetings Bugs. I have only recently started making yoghurt, even though I have had my thermomix for 7 years. Judy's idea may well be what is needed.
Is your daughter' scowl scrupulously clean?  I have had failures when I have had traces of yeast in my bowl.
I have been draining my yoghurt to get a thicker result. However it has set before I do this.
Hopefully some frequent yoghurt makers will be able to help.

[KristySpiegl]

I have found even a brand change in my ingredients can make my yoghurt fail to set properly.
If cleaning the bowl and using a new starter don't work, heat could be a factor. The easiyo loses heat quickly in cold weather, I wrap mine in a towel to add insulation in winter.