[levi86]

As a winemaker i use citric acid in the winery to neutralize cleaning agents like sodium percarbonate.
I keep a 50 pound bag in a sealed rubbermaid trash can that isn't airtight. Recently, in the past two weeks i noticed a noxious (kinda felt in the back of my throat with mucous) smell coming from the bag. Also the granules in the top of the bag semi melted in to a semi sticky layer about an 1/8 inch thick.  Keeping in mind i use a combination of Potassium Metabisulfite and citric acid 4:1 ratio in barrels with water to keep them fresh and inhibit yeast/bacteria growth. It is possible that someone accidentally got the KMS in the bag of citric but everyone denied this. Any thoughts on why this would happen? Does humidity chemically alter the makeup of the acid even at 40%  and 50 degrees F?
 Thanks for any help.

[Borek]

No idea. Can you describe the smell? AFAIR citric acid is not that hygroscopic, so I doubt air humidity alone was a reason for changes.

[Arkcon]

It could have gotten wet, and then spoiled.  As you well know, at low pH (acid) bacteria are inhibited, but fungi (your brewers yeast and common molds are examples) can thrive.  And thrive they will, even in moist powders that seem noxious at high concentrations.  Citric acid is a great nutrient for all living things - plugs right into the metabolic pathway called -- google for it - the Citric Acid cycle.

You can save as much of the bottom portion of the bag as you can -- whatever is still crystalline and dry.  Otherwise, it's back to the supply shop for you to replenish your older supplies.

Chemistry is my job, winemaking is my hobby.

[Borek]

It could have gotten wet, and then spoiled.

You mean wet like splashed with water? Could be. I was referring just to the situation as described - citric acid sitting in a sealed can.

[levi86]

Thank you for your replies.

No idea. Can you describe the smell? AFAIR citric acid is not that hygroscopic, so I doubt air humidity alone was a reason for changes.

Its not so much a smell as much as it is a feeling in my nose. Mucus forms in the back of my throat. I guess the only descriptors that comes to mind are metallic and pungent.

It could have gotten wet, and then spoiled. 

I don't think a significant amount got in there. The only possible way for it to get wet is if someone grabbed a wet plastic beaker to scoop the powder.

You can save as much of the bottom portion of the bag as you can -- whatever is still crystalline and dry.  Otherwise, it's back to the supply shop for you to replenish your older supplies.

You might be right about that.
thanks

[Arkcon]

It could have been contaminated with your potassium metabisulfite, as you originally guessed.  That sounds more to me like your symptom of a choking feeling, its what I experience when I dissolve pot-meta to sanitize something.  The melting to a sticky layer sounds more to me like some water splashed in.  Its all your call.

*EDIT* gotta spell that right

[levi86]

I put Potassium Metabisulfite next to citric acid and they look nearly identical. I believe someone accidentally put the KMS into the citric bin.
Thanks for all your help.