Author Topic: Lactobacillus and sugar water = gloop?  (Read 373 times)

Offline ccfoo242

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Lactobacillus and sugar water = gloop?
« on: January 09, 2014, 07:46:44 AM »
My son's biology project was to compare attenuation of brewers yeast and lacto using wort, apple juice, and sugar water. We prepared samples of nearly identical starting gravities if each and fermented in one-gallon growlers. The results were mostly as expected except for the sugar water. We used table sugar and filtered rap water and boiled for 10 minutes just like we did the wort.

But the one fermented with lacto (wlp677) came out with the consistency of hand sanitizer. Like a thin clear jelly. Also it smelled like nail polish remover.

Any ideas why it came out like this?




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Online mtnrockhopper

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Re: Lactobacillus and sugar water = gloop?
« Reply #1 on: January 09, 2014, 07:57:27 AM »
Nail polish remover might be ethyl acetate which I think you normally get from bacterial action on acetic acid and ethanol. That doesn't fully answer the question though. Hmm. Sugar water probably has a high pH compared to worry and juice. Lacto may not have been active due to pH and something else took off. There are organisms that cause "ropiness" in cider.

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Offline majorvices

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Re: Lactobacillus and sugar water = gloop?
« Reply #2 on: January 09, 2014, 08:36:31 AM »
Ropiness is the first thing that came to mind to me, too. Can't remember which organism causes that. Pedio?

Otoh Lactic acid is pretty thick and slimy.
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Offline morticaixavier

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Re: Lactobacillus and sugar water = gloop?
« Reply #3 on: January 09, 2014, 08:39:01 AM »
Ropiness is the first thing that came to mind to me, too. Can't remember which organism causes that. Pedio?

Otoh Lactic acid is pretty thick and slimy.

yes pedio. maybe others. But yeah, lactic bacteria produce a gel from milk, it's called yogurt. There are a lot more proteins in milk though. (like... some)

weird. can you test the pH? is the entire volume like that or is there different strata/textures?
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Offline ccfoo242

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Re: Lactobacillus and sugar water = gloop?
« Reply #4 on: January 09, 2014, 09:01:42 AM »
Starting ph was 7.19, ending was 4.07. I thought about the strata thing. Will have to pour it all out to see. We didn't know about the ph tolerance before starting. I've emailed white labs to get their thoughts also.




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Offline kylekohlmorgen

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Re: Lactobacillus and sugar water = gloop?
« Reply #5 on: January 09, 2014, 10:01:18 AM »
Ropiness from pedio usually takes quite awhile to develop in beer - pedio is a slow mutha, especially if its an infection (not a  cultured pitch).

Maybe the WL lacto strain can produce ropiness? Take a look at Wild Brews. I know it can produce a kind-of-pellicle, so that may be what you're seeing. I've only used the Wyeast culture, but I understand the WL version to be more akin to what you can culture from grain.

Side note: This is an awesome biology project. High School? Is he using Wild Brews as a reference?
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Offline ccfoo242

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Re: Lactobacillus and sugar water = gloop?
« Reply #6 on: January 09, 2014, 10:10:41 AM »
9th grade. He did it on my suggestion. Haven't looked at wild brews book though. I just told him that the typical homebrewer assumes that bacteria will ferment more of the sugars than yeast and the results bear that out.


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Offline kylekohlmorgen

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Re: Lactobacillus and sugar water = gloop?
« Reply #7 on: January 09, 2014, 11:05:10 AM »
9th grade. He did it on my suggestion. Haven't looked at wild brews book though. I just told him that the typical homebrewer assumes that bacteria will ferment more of the sugars than yeast and the results bear that out.


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Definitely a great source for report material. Deep topics, broken down in no-nonsense explanations.

Do you mind sharing the experiment and results when its done? I would have thought the opposite (yeast attenuates more than lacto).
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Offline ccfoo242

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Re: Lactobacillus and sugar water = gloop?
« Reply #8 on: January 09, 2014, 12:58:58 PM »
Yeah I'll post the tables this weekend.


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