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I've seen a lot of references on the Internet stating that vinegar mixed with baking soda is an effective way to disinfect mold, bacteria, etc. I'm skeptical that it has a significant effect because vinegar (and the result of mixing baking soda: sodium acetate) is not a particularly strong acid, and I expect that the acidity is the only disinfectant activity in this mixture.

However, many people tout the magic of vinegar and baking soda as a household cleaner.

Here's a sample quote:

Wikipedia

Vinegar, historically, has been reputed to have strong antibacterial properties. One test by Good Housekeeping's microbiologist found that 5% vinegar is 90% effective against mold and 99.9% effective against bacteria,[45]

And another:

White distilled vinegar is a popular household cleanser, effective for killing most mold, bacteria, and germs, due to its level of acidity. Cleaning with white distilled vinegar is a smart way to avoid using harsh chemicals. You’ll also be glad to know that it is environmentally friendly and very economical.

And another

Baking soda and vinegar kills all food germs and bacteria including E-coli and salmonella, naturally and safely.

A report from the University of Florida suggests that a mixture vinegar + lemon juice + baking soda results in a statistically significant reduction in tested bacteria, though it appears to be significantly less effective than the other cleaners tested.

How effective is vinegar & baking soda as a disinfectant?

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You've posted at least two things I'd call reliable sources (UoF's report, and Good Housekeeping's report) saying it does work. Major cleaning products (e.g. Windex) have vinegar-based product lines. What further evidence will convince you? –  user792 Oct 31 '11 at 13:26
    
@JoeWreschnig, Well, Windex is a window cleaner - I wouldn't use it to clean the kitchen top. Is there a sodium acetate product line for general household cleaning? I'd like to see a number of studies from reputable Universities demonstrating anti-bacterial and anti-mold properties of vinegar with (or without) baking soda. Given that this claim has been around since time immemorial, you'd think a few people would've looked into it. :) –  Brian M. Hunt Oct 31 '11 at 14:48
    
I've done this on shower mildew in a controlled way--spraying parts of the shower stall and not others, waiting ~30 minutes before washing off--and have noted a difference in the time the (parts of the) shower remains mildew-free. This doesn't say how effective it is, but the vinegar-soak was definitely doing something beyond the brief scrubbing with household cleaners (at least on the mildew in this particular shower). –  Rex Kerr Oct 31 '11 at 23:58
    
On the subject of University studies to scientifically show the effectiveness of vinegar and bicarb stuff on bacteria. It usually costs money for such studies, and who is going to fund those studies more than the companies who make the 'poisonous' products. And if the big companies pay for the funding, will there ever be an independent no-nonsense umpire who would oversee that study? Has there ever been such and independent judgement??? –  user8405 Sep 1 '12 at 12:18
    
@BrianM.Hunt - I use Windex to clean all kinds of stuff ... it's quite good –  warren Jul 12 '13 at 19:10
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2 Answers

up vote 7 down vote accepted
+50

There's a study here from the US National Library of Medicine National Institutes of Health website (Lukasik J, et al) entitled "Reduction of poliovirus 1, bacteriophages, Salmonella montevideo, and Escherichia coli O157:H7 on strawberries by physical and disinfectant washes."

This study describes the anti-bacterial effects of a "vinegar wash". Apparently using a vinegar based solution was 95% successful in removing bacteria from bacteria treated strawberries.

The efficacy levels of different physical and chemical washing treatments in the reduction of viral and bacterial pathogens from inoculated strawberries were evaluated. Escherichia coli O157:H7, Salmonella Montevideo, poliovirus 1, and the bacteriophages PRD1, phiX174, and MS2 were used as model and surrogate organisms. Chemicals readily available to producers and/or consumers were evaluated as antimicrobial additives for the production of washes. The gentle agitation of contaminated strawberries in water for 2 min led to reductions in microbial populations ranging from 41 to 79% and from 62 to 90% at water temperatures of 22 and 43 degrees C, respectively. Significant reductions (> 98%) in numbers of bacteria and viruses were obtained with sodium hypochlorite (50 to 300 ppm of free chlorine), Oxine or Carnebon (200 ppm of product generating "stabilized chlorine dioxide"), Tsunami (100 ppm of peroxyacetic acid), and Alcide (100 or 200 ppm of acidified sodium chlorite) washes. Overall, 200 ppm of acidified sodium chlorite produced the greatest reductions of microorganisms. Hydrogen peroxide (0.5%) was slightly less effective than free chlorine in a strawberry wash and caused slight fruit discoloration. Cetylpyridinium chloride (0.1%) was effective in the reduction of bacterial species, while trisodium phosphate (1%) was effective against viruses. The consumer-oriented produce wash Fit was very effective (> 99%) in reducing the numbers of bacteria but not in reducing the numbers of viruses. Another wash, Healthy Harvest, was significantly less effective than Fit in reducing bacterial pathogens but more effective for viruses. The performance of automatic dishwashing detergent was similar to that of Healthy Harvest and significantly better than that of liquid dishwashing detergent. Solutions containing table salt (2% NaCl) or vinegar (10%) reduced the numbers of bacteria by about 90%, whereas only the vinegar wash reduced the numbers of viruses significantly (ca. 95%).

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Blending vinegar (a dilute acetic acid) with baking soda (a base) essentially produces a neutral (neither acidic or basic) The chemical equation for the overall reaction is:

NaHCO3(s) + CH3COOH(l) → CO2(g) + H2O(l) + Na+(aq) + CH3COO-(aq)

where s=solid, l=liquid, g=gas, aq=aqueous or in a water solution. In other words, after the two compounds combine they first produce CO2 gas, water, aqueous sodium ions and aqueous acetate ions. The sodium and acetate ions eventually combine in the water to form a very mild sodium acetate solution (NaC2H3O2 + H2O).

According to one study you would need 1 gram of sodium acetate per 100 ml of water for the mixture to be effective to suppress aflatoxin produced by aspergillus parasiticus. Stachybotrys chartarum and aspergillus are two common household molds of which only certain strains of which are known to produce toxigens.

Assume the concentration of a liter of standard household vinegar (~5%) is combined with an appropriate amount of baking soda (~4 tablespoons). The yield should be around 2.3 grams per 100 ml of sodium acetate solution (assuming my math is correct) and would be sufficient as a mold suppressant.

The only issue might be any residual vinegar smell. You can buy anhydrous sodium acetate online and blend it with water for a cleaner, perhaps cheaper, solution.

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