Sudden problem with goat milk kefir

[bonwillow]

Hi ~ I love the Yemoos site and send everyone who wants to know about kefir here! I have been making kefir from low-pasteurized, unhomogenized, local goats milk for about two years now. I love it, and love watching my little grains grow and change. Last week I bought a different brand of low-heat-pasturized, unhomogenized, local goats milk. Everything else in my process was the same. On the third day, it had totally separated, with water (whey?) at the bottom and a thick, stinking, putrid mass on the top. It smelled horrible!

What in the world happened? Any ideas?

I rinsed my grains thoroughly, cleaned the jar, and put the grains back in. They look plump and white and healthy, and smell nice after being rinsed. They don't appear to be dead. Not having any other options, I poured a little layer of the same (new brand) goats milk over them. Should i just try again? Maybe a bug flew into the kefir and made it turn bad??? Other ideas...?

[AlexP]

A couple thoughts. What you are describing sounds like kefir that is over fermented (All the whey at the bottom and tons of curds on the surface). It's unlikely that any kind of contamination could cause that. You mention that you used a different brand. When you use raw milk or milk that has a lot of good bacteria, it tends to ferment much more bacteria rich and slower and is less likely to separate into curds and whey quickly. So perhaps that new brand is significantly more pasteurized or lacking the good bacteria that the last brand had. It shouldn't cause any issue with your grains and they will probably adapt to the new milk. Try using less grains or more milk and see if that helps.

Alex

[bonwillow]

Thanks so much, Alex. That was helpful. UPDATE: As mentioned, I cleaned the grains and poured more of that new brand of goat milk over them. Three days later... totally separated, and a stinking horribly smelly mass on the top. Once again I cleaned the poor grains, and put them in a jar of purified water. Today I got some of the original brand of goat milk. I'm betting that it will be just fine this time.

Alex, I have one more question: You suggest that the new milk probably was more pasturized and/or had less good bacteria. I understand that, and agree that probably that's the case. But why the stinking spoilage of the top layer? I don't understand why it was ruined. Maybe... because it didn't ferment very effectively, it just spoiled like any unrefrigerated milk would do?

[AlexP]

No problem at all. When it does separate quickly and it over ferments like that it tends to give off a strong yeasty smell and if its goats milk, it can contribute to some even stronger smells. I'm not sure if I would say that its typical to smell like spoilage or rotten milk though. Sometimes if the ferment or grains are imbalanced, it can smell really horrible. Hopefully the change to the old milk will fix it. If the grains are a little imbalanced now, it may take a couple or so batches to get back to normal. Keep us updated!

Alex