After my experience with WLP672 Lactobacillus Brevis, I’ve wanted to explore some other methods for quick souring wort. The first and most obvious choice was to try using grain. I’d also heard of others trying yogurt cultures to sour wort. Since I had just gone to the grocery store I had fresh yogurt on hand.
Though I’ve read that taking certain precautions such as lowering pH and purging the headspace with carbon dioxide can yield better results, I decided to try without this time. I’m ultimately looking for the simplest most repeatable method.
I set the containers up on a heating pad with a controller in one of my fermentation chambers set at 95F (35C).
1/29/15, 48 hrs:
The yogurt starter didn’t look too exciting, just like the yogurt has separated out of the wort.
I’ll be tossing out the grain starter to try again. Next time I’ll purge with co2 and start off with an acidic environment. That may prevent the bad phenols from forming. I will continue to monitor the yogurt starter to see how acidic it will get.
1/30/15, 72 hrs:
The yogurt culture has reached pH 3.34 within 72 hrs. Still tastes clean with more tartness now and is getting to the point where you can feel it just a tiny bit in the back of your cheeks.
1/31/15, 96 hrs:
No further drop in pH on the yogurt culture. It is considerably more tart than my result with WLP672 and reached this level in 3 days. Through further experimentation I may be able to find the ideal conditions for the yogurt culture to perform better. I will definitely consider this method for my next quick sour beer. It produced a very clean and significant amount of tartness using a readibly available culture. Its less expensive than buying a culture at around $4 a tub, and I can eat what I don’t use. Also, due to food industry standards, I probably don’t have to worry about the quality and viability of the culture.