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Distilled White Vinegar Contamination

contamination white vinegar vinegar tpc white vinegar

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Posted 28 October 2014 - 04:11 AM



I am first time writing here from Malaysia. I have been following most of the forums and I get lots of informations. Thanks to IFSQN. 


My question is.... We are producing salad dressing and one of the ingredient is distilled white vinegar. We are currently storing the distilled white vinegar in a stainless steel tank. From what I observed, there is formation of slime in the tank after over 1 week of storage. When tested for microbes, there were high TPC and presence of coliform. 


Then, we cleaned up the tank with sanitising cleaner and sprayed sanitiser before storing the second round of vinegar. Exactly a week later the slime formed again. 


Can the vinegar be stored in stainless steel tank? Vinegar supposed to last longer than water or oil ( as we have oil and water tank too). 


Please advice. Thank you.


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Posted 28 October 2014 - 12:21 PM

Hello Mr chrisgal21,

                   please check the acidity  level of distilled white vinegar(should be between 5-6%).Also check the COA (certificate of analysis for physical,chemical , Microbiological parameters for vinegar  received from the vendor.

 If everything okay the contamination may  be from your side for certain microbes being able to grow in vinegar or  vinegar getting diluted from some contamination like starch,dust flowing in s.s. tank in your factory.

 You  can  use /receive your vinegar in plastic drums or make your own vinegar  from the glacial acetic acid.


Ian R

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Posted 28 October 2014 - 05:27 PM


As Sushil as mentioned you need to check the acidity.

Distilled vinegar is normally used at 5-6% but is actually fermented much higher, 10-12% even as high as 15% under the right conditions.


Depending on your local regulations you might find that using acetic acid does make vinegar, it makes NBC non brewed condiment.

I can only comment on UK legislation which requires a fermentation process followed by acetification.

Distilled vinegar or white vinegar is then mage by the distillation of other vinegars normally malt.


The usually contamination in vinegar, especially as a slime, is "mother" or acetobacter, but this harmless and usually an airborne contaminant.


if you are getting high counts on TVC and coliforms this would suggest low acidity and some form of contamination.




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Posted 28 October 2014 - 05:43 PM

Vinegar is acidic, and no matter how good your stainless steel is, the vinegar will slowly attack it.  When vinegar attacks a metal, the acid gets used in the process, which would allow the pH to rise to a more neutral range.  Although you see a scum forming very soon, maybe having a lower acid vinegar and a large surface area of stainless steel to work on, makes you lose the acid quickly.


My advice is to store the vinegar in a plastic container.  Polyethylene is not attacked by acetic acid (the acid in vinegar) and is safe for food.  Glass is also safe, but raises the risk of broken glass.  When you buy acetic acid as a chemical, it is always in glass or plastic.



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Posted 28 October 2014 - 10:22 PM

Hello, actually we have the same situation as u. As we will buy the bulk rice vinegar with acidity at 10 and then stored at the PE tank, there will not be forming the slime however when we dilute the vinegar to 2% and keep in pe tank , slime will be formed very quickly. Acidity of the vinegar is very important and the supplier told us the reason is because of the air contamination and if u can keep the vinegar at around 7%, that would be fine


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Posted 29 October 2014 - 01:46 AM



Thank  you so much for all your comments and feedbacks.

Now I have good understanding on these issue. 


Thank you once again.




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