April 12, 2012

Fun with probiotics and sour mashes

A handful of people on HomeBrewTalk.com have mentioned using various sources for lactobacillus with good results, including using acidophilus probiotic tablets (acidophilus is lactobacillus acidophilius) or the liquid part of unpasteurized yogurt, which also includes acidophilus. Internet sources say the acidophilus strain can survive up to 10% ABV and low pH so it's a good candidate for getting noticeable sourness. I wanted to give this a try and see if it produces any off flavors. My wife has some multi-strain probiotic pills that include lactobacillus strains brevis and acidoplihus along with a bunch of other lacto strains and yeast.

My goal was to produce something oud bruin-like without the time delay. I thought there was a chance the multitude of strains would produce enough complex flavors and survive long enough to get some good solid sourness. If it turned out ok I could use it to keep a less-sour beer in rotation. I could save the cake and try souring different kinds of beers to get a good mixture of tart beers. It could make for interesting blending experiments.

I brewed up a quick one gallon batch of brown ale and tossed in some WLP575 and the contents of one of the multi-probiotic tablets. I got good fermentation out of the WLP575 but then things seemed to calm down. No pellicle or funky krausen. I got some bubbling from the trub for several weeks. I gave it a taste. It tasted fine but no sourness whatsoever. I added the contents of another tablet and let it sit. Still more bubbling. No sourness. Experiment failed.

So I decided maybe I could get a sour mash going with this stuff and then blend it into the brown ale. So I first tried (boiled) water and straight table sugar to see if I could get fermentation going. I added the contents of a tablet. Nothing. Kept hitting it with heat. Nothing. A hint of an off flavor. I could see that there was some growth on the bottom of the container because small white masses would grow larger each day. But still no change in flavor or aroma. I added more sugar, thinking maybe I just didn't add enough. Nothing. I tasted it a couple of weeks later. It was very sweet so nothing happened. I tried adding some yogurt liquid from unpasteurized yogurt. Still nothing. Experiment failed.

I wasn't too surprised, it's usually very difficult to get good fermentation on straight sugar because bacteria and yeast need certain nutrients (this is why mead fermentations require nutrient additions to ferment out in a couple months rather than a year). So I made a small amount of wort with some pale malt and added boiled and cooled wort to the existing liquid. After a day, nothing. I keep trying to keep it warm to increase activity. So far, I still have nothing going on. This morning I added another tablet.

At this point I'm completely surprised I'm not getting any visible activity. My sour worts usually get strong, visible krausen after a day or two but I've got nothing. No weird smells. I know the strains selected for probiotic pills tend to survive in warmer climates than I'm giving it and to break down complex sugars but I've never read that lactobacillus won't break down simpler sugars. I'll probably give what's in there a couple more days to get busy. If it doesn't work, I'll toss some grains in and let more aggressive strains dry it out. Then I'll boil it clean and try blending.


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