by gazaah on Sat Sep 09, 2017 6:11 pm
I've found most freeze dried cultures from Amazon work well. I sometimes shop at my local "natural foods" store, which I love for some items. But their starter had been on the shelf for quite some time when I bought it. The first box was a dud and the second box, with a much newer date on it, worked fine.
The freeze dried cultures if stored and shipped properly can be nice because you can load your batch with huge numbers of microbes and get a strong set quickly. I go for several batches in a row and then start fresh when the process changes, indicating that my culture's make up has changed. Sometimes I accidentally evolve my culture and select for bacteria that like being in the fridge by accident. Then I find my yogurt sets completely 2 days after incubation. That is not my goal but weird things happen when you go from batch to batch with fridge and heat in the equation.
I have had great results with "live and active cultures" plain, unflavored store yogurt if I used half to a full cup per 5-6 cup batch. I did NOT have great results trying with drinkable yogurt with 12 species listed on the side. I'd suggest using a starter yogurt that has only has one or a few species on the label. The simpler you keep your source the better you can troubleshoot what part goes wrong in a failed batch if you are the experimenting kind.
Once you have a couple really reliable recipes, then you can mess with the started culture and know where the failure lies, in my experience.