Re: [CH] Re: Cleaning/Sanitization
Jim Graham (spooky130@cox.net)
Wed, 20 Feb 2008 11:31:26 -0600
On Wed, Feb 20, 2008 at 11:00:37AM -0500, Cameron Begg wrote:
> At 8:25 AM -0600 2/20/08, Jim Graham wrote:
> And the gas you produce is hydrogen. Very spectacular results are
> possible!
Ah, now that I didn't know. (I'm not a chemist...my degree is
electronics/telecommunications.)
> Weight for weight the sodium salt has more bang, but in practice I
> doubt you will notice the difference.
For all but the worst in dirty equipment, I agree 100%. And don't
mistake my referring to KOH as "safer" to mean that it is 100% "safe"
(i.e., you should still be wearing protective clothing---rubber gloves
and eye protection at a minimum).
>> Or Iodophor,
> Do not put chlorine containing chemicals like sodium hypochlorite
> (bleach) into stainless steel or aluminum.
That's another reason why iodophor is used instead of many other
sanitizers in the brewing industry---used at the proper concentrations,
it is safe for stainless steel, where bleach causes pits in the walls
of stainless vessels, leaving a nice breeding ground for bacteria.
Note the key words (echoing what Cameron said): "at the proper
concentrations."
> For brewing beer it won't matter. (De Clerk in the "Textbook of
> Brewing" was probably talking about sterilizing equipment and culture
> media for yeast propagation.)
Yes, he was. My reason for pointing that out was, once again, to make
the distinction between merely sanitizing and actually sterilizing. I've
been taught never mix those two up.
> You actually need oxygen to ferment beer
Well, taken exactly as written, that's not true (it's missing some bits).
When you pitch brewing yeast, you're pitching a quantity that is not
sufficient to ferment the wort (unless you're overpitching, which can
result in a number of different flaws that adversly impact the flavor
of the beer). Once pitched into the wort, the yeast (which, if you've
made a good starter, is at high kraeusen---never can remember how to
spell that one) switches from its anaerobic fermenting cycle back to a
reproductive cycle, during which they require oxygen. After the O2 is
all used up, they stop reproducing and start feeding (fermenting). And
if you don't think anaerobic bacteria survives that, think again...back
when I was first starting out with all-grain, and my cleaning/sanitizing
procedures weren't as strict as they are now *AND* I wasn't doing yeast
starters *AND* I was relying on shaking the fermenter instead of cranking
in pure O2, I had some Pediococcus-infected batches...the infection was
the result of bacteria from the grain itself that survived not only the
90 minute boil, but also the aerobic cycle. Because the yeast wasn't
strong enough to beat out the Pediococcus, they "shared" the wort, and
the result was horribly phenolic, infected beer.
Now, I do realize that the above is not directly CH related, but it is
directly related to this topic: the point being, some types of bacteria,
or should I say, some strains of probably any genus/species of bacteria,
are HIGHLY resistant to all of our attempts to kill them. If your
requirement is "sterilized" material (e.g., when handling yeast), you
have to consider absolutely everything. If you're only interested in
"sanitized" (say, 99.99995% kill---ok most of the time), there's still
a lot to consider (scratches in plastic serving as a nice breeding
ground, etc.), but the discussion gets a lot simpler.
So for the other CH folks who aren't brewers, please bear with us as we
go momentarily to a related, but still off-topic, subject, because it
all rolls right back into this topic. :-)
> and this means that anaerobic bacteria will not survive.
See above. Most of it is killed in the boil. A lot of it probably
won't survive while the yeasties are making more little yeasties.
And if the yeasties are strong, healthy, and reproduce to a large
enough quantity, the few remaining cells of Pediococcus and/or
Lactobacillus that came in with the grain and survived to get that
far will be starved out as the yeast chews up all of the fermentable
sugars (well, ok, actually only to the % attenuation of the strain
you're using). As long as your cleaning/sanitizing practices are
good, and your nice, healthy yeast beats out the bacteria, you really
don't need to worry about it. Since I learned proper cleaning and
sanitizing in the brewery, started up my own yeast bank on agar
slants (which is where "sterile" comes into play---this is where you
have to get really crazy about everything being truly sterile), and
started using pure O2 instead of just shaking the fermenter around,
I've never had an infected batch.
> One other class of sterilizing chemicals comes to mind - the quaternary
> ammonium compounds
Quat! Yeah...good stuff for the walls and floors in the brewery, as
well as the outside of the hot liquor tank, mash/lauter tun, brew kettle,
fermenters, brite tanks, etc.....
Fun discussion! Hopefully this is useful info for the group.
Later,
--jim
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