# Sterilization Agents



## mark500 (Feb 4, 2009)

Potassium Metabisulfite seems to be the most common chemical used for wine equipment sterilization. What aren't hydrogen peroxide ordiluted bleach used more, as long as the equipment is allowed to dry?


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## grapeman (Feb 4, 2009)

I'm sure PeterZ will give you a complete explanation for this since he has more of a chemist background. I use k-meta because it works well and is relatively inexpensive. The sulfates in it are the same as is produced naturally by the fermentation and is used as a preservative and anti-oxidant.


Generally bleach - chlorine - is not used in winemaking at any stage. Any residue in the wine can lead to TCA or cork taint.


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## Tom (Feb 4, 2009)

mark500 said:


> Potassium Metabisulfite seems to be the most common chemical used for wine equipment sterilization. What aren't hydrogen peroxide ordiluted bleach used more, as long as the equipment is allowed to dry?








Mark 
I use k-meta also BUT it will *not sterlize*. It sanitises. 
One reason not to use what you asked is they all need to be fully rinsed. If you don't this fully it will react with off flavors. We try to avoid that because tap water can have "buggers" then nothing is sanitised.
K-meta is cheap so it's not a $ savings by using bleach.


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## smurfe (Feb 4, 2009)

Tepe is on the money. We don't sterilize, we sanitize. There is a difference. Look at it this way. We clean and then we sanitize. You can use diluted bleach to sanitize but it must be rinsed thoroughly. Once you rinse the item with water that is not sterile or sanitized the surface isn't sanitized anymore. Now will it still be safe to use? Probably if you clean very very well and then sanitize. I know many beer brewers that use bleach to sanitize and then rinse and have no issues. Some cleaning agents such as B-Brite are chlorine based. Beer is extremely more sensitive to infections than wine is. As stated, for the price of K-Meta or Na-Meta (which I use) it is a very cheap and proven effective sanitizer that doesn't have to be rinsed.


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## Tom (Feb 4, 2009)

Smurfe,


I don't use bleach because it may pit the stainless kegs. Rather I use the brandX oxygen cleaners for cleaning and Idophor for sanitizing when I make BEER.


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## grapeman (Feb 4, 2009)

To expand a bit on my reference to Cork Taint, here is an article from WineSpectator Magazine. All credit for the following is to them and here is a direct link 
http://www.winespectator.com/Wine/Features/0,1197,3568,00.html



<H1 ="title">Wine Flaws: Cork Taint and TCA</H1>
<H5 ="postdate">_*James Laube* and staff_</H5>
<H5 ="postdate">Posted: Tuesday, January 09, 2007</H5>


You've opened a bottle of wine that's supposed to be outstanding. But when you put your nose to the glass, it smells like something you pulled out from a forgotten corner of a damp basement. What's the problem? Most likely it's TCA.


*What is it?* 
TCA stands for 2,4,6-trichloroanisole, a chemical so powerful that even in infinitesimal amounts it can cause musty aromas and flavors in wines. The compound forms through the interaction of plant phenols, chlorine and mold. It most frequently occurs in natural corks (TCA can even form on tree bark) and is transferred to the wine in bottle--which is why wines with these off-aromas are often called "corky." But the taint can originate elsewhere in wineries, where damp surfaces and chlorine-based cleaning products are commonplace; barrels, wooden pallets, wood beams and cardboard cases are all sources of phenols. If TCA goes undiscovered, it can spread and eventually taint the wines.


*How do I recognize it?* 
Although TCA taint poses no health concerns for wine drinkers, it can ruin a wine. At higher levels, it makes a wine smell moldy or musty, like cardboard, damp cement or wet newspapers. At its worst, the wine is undrinkable. At lower levels, TCA taint merely strips a wine of its flavor, making normally rich, fruity wines taste dull or muted, without imparting a noticeable defect. This can leave drinkers disappointed in a wine without being able to pinpoint why.


Experts say people vary widely in their ability to perceive TCA in wine, depending on their genetics and experience. Some cork producers claim that levels of 6 or even 10 parts per trillion (ppt) are acceptable, as many people won't notice TCA at this level. However, research in Europe and at the University of California, Davis, indicates that some tasters can detect TCA at 1 ppt to 2 ppt, and a rare few can perceive it at even lower levels. People with higher threshold levels may perceive an off characteristic without being able to identify it.


There is no legal standard for acceptable TCA levels in wine.


*How common is it?* 
As with thresholds of perception, estimates of TCA-taint frequency in vary widely. The number typically ranges from 1 percent to 15 percent of all wines, depending on whether it comes from closure manufacturers, vintners or another source. _Wine Spectator_'s Napa office tracks the number of "corky" bottles in tastings of California wines, and the percentage of defective corks routinely runs at 15 percent. At the magazine's California Wine Experience in 2004, the team of sommeliers who screened the wines for the seminars reported that the occurrence of “corky” bottles was 4 percent to 12 percent. The cork industry has a different estimate of cork failure: typically 1 percent to 2 percent.


*Are there other causes of "corky" wines?* 
Yes. When repeated bottles of the same wine, multiple wines or multiple vintages from a winery show the same flaws, the problem is not likely due to a few bad corks. There may be widespread cellar taint.


Many cases of taint are caused by other environmental problems at wineries, such as moldy cellars, antifungal treatments and flame-retardant paints. Like TCA, a compound called 2,4,6-tribromoanisole (TBA) gives off musty, papery aromas; it is used in preservatives to treat wood. Contamination from chemically treated woods in renovated cellars plagued many estates in France, particularly in the 1990s. Some properties had to tear down and reconstruct buildings to eradicate the problem.
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## smurfe (Feb 4, 2009)

Diluted bleach is OK on stainless but you need to rinse well. You don't want to use it on aluminum pots though as it will pit. I have used it many times on stainless pots after boiling shrimp,crabs, and crawfish with no issues.I use the Oxy Clean products to clean as well and use Star San to sanitize. I have started using it for wine to.


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## Tom (Feb 4, 2009)

Smurfe,

OXY also does a great job on carboys and plastic buckets. It takes all the "crud" off the walls for both Beer and Wine. Just make sure you rinse well.


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## smurfe (Feb 4, 2009)

If you don't rinse very well you do stand a chance for TCA. Does anyone know if you can get TCA with the Agglomerated cork most use? I always thought it was a risk with real, natural, traditional corks.


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## smurfe (Feb 4, 2009)

tepe said:


> Smurfe,
> 
> OXY also does a great job on carboys and plastic buckets. It takes all the "crud" off the walls for both Beer and Wine. Just make sure you rinse well.




Yup, I know. I use it to clean everything. Some good stuff. I had a flask here a while back I burnt DME in making a starter. I was gonna toss it but threw in some OXY and the next morning it was spotless clean. I still think Oxy and One Step is the same stuff.


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## grapeman (Feb 4, 2009)

smurfe said:


> If you don't rinse very well you do stand a chance for TCA. Does anyone know if you can get TCA with the Agglomerated cork most use? I always thought it was a risk with real, natural, traditional corks.




I am not sure if the extra density of the cork would prevent TCA Smurfe. Agglomerated corks are still real cork just shaved tolike a sawdust consitency and glued together. Since it is still real cork I would suspect that it could still be susceptible to TCA.


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## PeterZ (Feb 4, 2009)

Bleach, hydrogen peroxide, and organic peroxides like Oxyclean are all sterilizing agents at the proper concentration and contact time. All of them will also have the same effect on wine as exposure to oxygen - it will ruin the wine. That is why we don't use them.


If you see some mold or bacterial growth in your primary buckets or carboys then a rinse with one of those agents is appropriate. They are "hard surface sanitizers" - a term with legal and regulatory significance - and will kill off the infestation when used as labeled for that purpose.


Once you have done that, however, it is necessary to remove the oxidizing agent so it does not oxidize the wine. Potassium metabisulfite (K-meta) (and all sulfite compounds) are reducing agents, the opposite of oxidizers. They will cancel each other out.


From a practical standpoint the reason we use a solution of K-meta to "sanitize" our equipment is that the organisms that can harm our wine all require free oxygen for their metabolism. The K-meta consumes all the oxygen, so they are forced into dormancy. 


Once the yeast in a must takes off it out-competes any other organism. After the wine is finished, the presence of SO2 from the K-meta inhibits any of the bad organisms.


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