I have read and reread all the Yogurt recipes but haven't seen an answer for 'runny' Yogurt, but I believe I have found the answer to this problem and possibly other whey problems.
We have been producing Yogurt for some time in a machine, tried a variety of recipes but still find it's runny. I happened on Ms Carrol's web site where someone asked for the answer to 'thin' Yogurt and her answer is to heat the milk to 185F and hold it there for 10 -20 minutes.
In her own words 'to take advantage of the whey proteins which help to make it firm'.
Yesterday we made up another batch using this idea and it worked. For the first time ever a good batch of firm creamy Yogurt. At the same time we took some to make drained Yogurt cheese and the whey was clear as water, with no cream runoff.
Recipe as follows:-
1 litre of Homogenised whole milk.
1/2 cup of Skim milk powder
2/3 cup of active Yogurt starter from the store
Method. Heat the milk to 185F and hold at that for 20 minutes.
Cool to 110F
In a bowl add starter and milk powder and stir to cream together,
slowly add a cupful of milk at 110F and stir to incorporate. When creamy and smooth, slowly add the remainder.
Add the whole mixture to the machine and time for 10 hours.
This has to be the finest Yogurt we've ever tasted, slightly tart, smooth and creamy with no graininess. Add a small amount of your favourite fruit after cooking for the tastiest treat ever.
The next question I have. What effect would pre-heating the milk and holding it have on cheese making? Would it help prevent the cream leak into the whey?