Hi everyone, I'm new here.
I'm just starting out with mesophilic yogurt (specifically matsoni from a Japanese starter and viili from Gem Cultures). The instructions from Gem Cultures for the viili make it clear that they do not recommend sealing the viili into an airtight container -- neither during active culturing nor in the refrigerator. They suggest culturing with waxed paper or a saucer over the yogurt bowl and refrigerating in a container with the lid loosely in place. Instructions for the Japanese culture suggest that their matsoni be cultured in a sealed container, saying that the headspace in the container should provide enough air, and that keeping a closed container is important for preventing contamination.
My main question: does matsoni not require oxygen? Viili seems to (and that makes sense, given its history, its association with a mold, and the common advice to culture it in bowls -- so with plenty of surface area). The idea of an anaerobic jar of fermenting dairy sitting on my counter seems... well... potentially more dangerous than the possibility of wild house-dwelling bacteria getting in my yogurt. Am I wrong? Can I just cover the matsoni with a clean cloth, as I had planned? Or should I keep it sealed?
Secondary question: If I seal these in containers in the refrigerator, leaving some head space in the containers, would that damage the cultures? If I should NOT seal the containers, how to prevent cross contamination in the refrigerator? Aside from the two types of yogurt, there is also obviously cheese, etc, in there.
Thanks for any answers or experiences you might have!