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Bacteria

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DarrenTheDrunk

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Hi all

Here comes another post only minutes after the previous one. Clearly I am bored but as a new brewer, I think a lot about it and whilst I am light years behind the technical skills and knowledge of someone like DAZ and Grmblz ..I love to learn. Ok, we are all told to be "anal" about sterilization to ensure bacteria does not enter the process but I thought that bacteria needs oxygen to survive and given the "oxygen zapping" Co2 is present, I would have thought that bacteria should not be a problem. This is unless the bacteria is anaerobic but still, surely this type of bacteria would not be an issue until oxygen became present which ordinarily is at drinking time. So my previous post was to the math guru's... I guess this one is for the "Mad Scientists" out there.

Cheers and Beers

darren
 

JDW81

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Hey Darren,

There is a difference between sterilisation and sanitisation. It is virtually impossible to sterilise brewing gear. What cleaning and sanitising aims to do is remove and kill the organisms that are likely to spoil your beer (mostly things like wild yeasts, but there are others).

Remember CO2 Is only present once active fermentation starts, and yeast require oxygen in the initial stages of fermentation. Wort is also never truly an anaerobic environment. CO2 also doesn’t “zap” O2. The yeast initially use the O2 in the wort, and then start to produce CO2 and ethanol further down the track. As fermentation progresses the O2 content will fall, and the CO2 content will rise, but that is due to the metabolic processes of the yeast.

All home brew will have some form of contamination, it just isn’t sufficient to spoil the beer, as the yeast quickly becomes the dominant organism and makes it much harder for other bugs to take hold.

Also worth bearing in mind that aerobic bacteria/organisms can grow in low O2 environments and anaerobic organisms can also grown in solutions with some O2 So don’t be fooled into thinking that the “blanket” of CO2 above the wort or the CO2 in the wort is going to completely protect it.

There’s some good podcasts on the brewing network about yeast/fermentation/bacteria/sanitisation/many other brewing topics which are pretty basic and explain the important aspects. There’s also lots of other great resources around which are worth a read (Yeast: a practical guide to fermentation by Chris White et al is also worth a look at if your really keen). Also worth having a look a Braukaiser (German brewing blog).

JD
 

MHB

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There are a bunch of bacteria and wild yeast that have adapted to living in post fermentation conditions notably; Lactobacillus, Acetobacter, Pectinatus... many more.
CO2 isn't "Oxygen Zapping" it merely displaces it under some conditions but the two can coexist (like in the air) as a mixture.
You really do need to be anal about cleaning and sterilising, if you think bacteria aren't a problem you can be grievously wrong.
Mark

Edit
Go to Google and search for "common beer spoilage bacteria" and there is plenty of good information.
M
 

Grmblz

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Easiest way to "STERALISE" something, put it in your oven @180c and wait for 3.5 hrs, it's now "sterile", of course as soon as it's cooled and removed from the oven, and subjected to the air we breath it becomes contaminated again. As ^ & ^^ point out it's all all about getting the contamination to a level low enough that we can't detect it in our finished beer.
btw I suspect MHB has forgotten more than I know, just sayin.
 

BrewLizard

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Have a look at facultative anaerobes. Many of these bugs can thrive in O2 replete or O2 deplete environments. The lovely Salmonella and Listeria genera are examples of these.

Easiest way to "STERALISE" something, put it in your oven @180c and wait for 3.5 hrs, it's now "sterile"
If only. Air is a very poor conduction medium for heat, especially when sterilising. You could certainly disinfect with this method (and call it sanitised), but it will be far from sterile. Wetting everything before putting it in the oven will also help with heat conduction and steaming bacteria, but it's a far cry from autoclaving. (Nvm; see below.)

Definitely agree that in home brewing, it's all about getting bacterial colony levels low enough, rather than sterile.
 
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Grmblz

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If only. Air is a very poor conduction medium for heat, especially when sterilising. You could certainly disinfect with this method (and call it sanitised), but it will be far from sterile. Wetting everything before putting it in the oven will also help with heat conduction and steaming bacteria, but it's a far cry from autoclaving.
Sorry mate but you're wrong Sterilizing with Steam Versus Dry Heat look at the recommended temps and times and you will see that 170c for 1.5hr kills everything, spores included, so 180c for 3.5hrs is way over the top (on purpose as some ovens may not reach 180c) There are pro's and con's to both dry and wet sterilisation, for example how are you going to autoclave water soluble powders or ferrous metals, on the other hand rubber and some other materials wont handle 180c so as usual it's a horses for courses scenario.
I certainly agree that autoclaving is the preferred method, if for nothing more than speed and efficiency but not everything can be autoclaved and not everyone has one, whereas you'd be hard pressed to find someone without an oven.
 

BrewLizard

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Apologies, Grmblz. Seems I underestimated the simplicity of dry heat sterilisation, and assumed there was more to it (e.g. pressure) than an oven could do. I'm unable to load your link (tried 3 different browsers and just got a white page), but I did some other reading. Mea culpa.
 

Grmblz

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Well that's a bit strange oh well Goggle labmanager.com/product-focus/sterilizing-with-steam-versus-dry-heat-1875
 

Nullnvoid

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Easiest way to "STERALISE" something, put it in your oven @180c and wait for 3.5 hrs, it's now "sterile", of course as soon as it's cooled and removed from the oven, and subjected to the air we breath it becomes contaminated again. As ^ & ^^ point out it's all all about getting the contamination to a level low enough that we can't detect it in our finished beer.
btw I suspect MHB has forgotten more than I know, just sayin.
I tried to sterilise my fermzilla this way. Did not go well! Cannot get the bastard to seal anymore! hahahaha
 

DarrenTheDrunk

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Hey Darren,

There is a difference between sterilisation and sanitisation. It is virtually impossible to sterilise brewing gear. What cleaning and sanitising aims to do is remove and kill the organisms that are likely to spoil your beer (mostly things like wild yeasts, but there are others).

Remember CO2 Is only present once active fermentation starts, and yeast require oxygen in the initial stages of fermentation. Wort is also never truly an anaerobic environment. CO2 also doesn’t “zap” O2. The yeast initially use the O2 in the wort, and then start to produce CO2 and ethanol further down the track. As fermentation progresses the O2 content will fall, and the CO2 content will rise, but that is due to the metabolic processes of the yeast.

All home brew will have some form of contamination, it just isn’t sufficient to spoil the beer, as the yeast quickly becomes the dominant organism and makes it much harder for other bugs to take hold.

Also worth bearing in mind that aerobic bacteria/organisms can grow in low O2 environments and anaerobic organisms can also grown in solutions with some O2 So don’t be fooled into thinking that the “blanket” of CO2 above the wort or the CO2 in the wort is going to completely protect it.

There’s some good podcasts on the brewing network about yeast/fermentation/bacteria/sanitisation/many other brewing topics which are pretty basic and explain the important aspects. There’s also lots of other great resources around which are worth a read (Yeast: a practical guide to fermentation by Chris White et al is also worth a look at if your really keen). Also worth having a look a Braukaiser (German brewing blog).

JD
WoW.. I leaned a bucket load from your reply JD...Thanks Heaps
 

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