Problem with culture..

[Bernardsmith]

I have been using my kefir to ripen milk for my cheeses for about a year or so. Last night I started a feta -type cheese (1 gallon of milk) and I used about 1 cup of whey I had collected from some kefir (collected over a few weeks). Normally, I use about 1/2 cup of the day's kefir but after about 60 minutes of ripening I saw that the milk had already significantly curdled - the rennet I added did not give me any additional coagulation. I did not check the pH of the whey last night but the other day I did and it was down to about 4.3. Is that the reason why the milk curdled? Should I avoid using this whey for ripening? Should I use far less whey? Should ripening time be reduced considerably? The "feta" is currently still draining for another half hour (12 hours) but I checked it earlier this morning (around 5 hours ago) and it did appear to be hanging together adequately.. but I have yet to try to slice and salt it. Thoughts? Thanks. 

[River Bottom Farm]

For sure the acidic whey curdled your milk. If you use whey again use less and see how it goes. It may just not be suitable. What cheeses have you been making with kefir as the starter?

[Bernardsmith]

Squeaky curd, "Feta", Caerphilly, Cheddar, Mozzarella.  I used David Asher's process (though not his recipes) as found in Making Cheese the Natural Way. But typically, I use a batch of the day's kefir as my starting culture. What I used for this batch of "Feta" was the whey I had collected after making a cheese from the kefir itself. I checked the pH of the kefir whey this morning and it was about 3.9 - significantly lower than the kefir I usually use