Whey: Lacto-fermentation Fail

Unfortunately, my ginger bug passed away due to neglect: I forgot to feed it a few times and sometimes just fed it sugar because I didn't feel like cutting up ginger root.  

So, I decided to try making lacto-fermented soda the easy whey (pun intended).  I drained off half a cup of whey from the most recent batch of my Matsoni yogurt (I LOVE Mesophilic yogurt cultures), and added it to some sweetened ginger tea and waited for it to become fizzy.

Five days passed and it did not become fizzy, but it did become moldy. Perhaps I should have sterilized my jars directly before (they were run through the dishwasher, so I thought that was good enough). I had poured the mixture into four different jars and three ended up growing mold in them, which leads me to believe it was a problem with the whey.  Maybe I need to use whey from Bulgarian yogurt?

I did sample some of my concoction on day three even though it was not fizzy, it had a weird milky taste, not just the slight fermented taste that I had ended up with when making soda with my ginger bug.

I may try this experiment again in the future either using different whey or sterilizing the jars directly before.  Anyone have any success with making soda using whey?

I ordered some water kefir grains finally after reading about all the crazy health benefits of kefir, so I will be attempting kefir soda in the next few weeks. Wish me luck!