Bleach and vinegar

[Dave S]

Hi guys

I read recently, on another forum I think, that household bleach only works as a steriliser if an acidic such as vinegar is added to the bleach/water dilution. I've never heard of this before. Can anyone verify/refute?

[Andy]

Diluted bleach will work as a sanitiser, it's effectiveness can be increased by acidification of the solution I believe. Need to be careful however as nasty gases can be released and never add the acid to the bleach in undiluted state, always dilute the bleach first then add the acid (see nasty gas comment for reason ).

Most people just use a diluted bleach soln without adding any acid though and get on fine.

[Dave S]

Diluted bleach will work as a sanitiser, it's effectiveness can be increased by acidification of the solution I believe. Need to be careful however as nasty gases can be released and never add the acid to the bleach in undiluted state, always dilute the bleach first then add the acid (see nasty gas comment for reason ).

Most people just use a diluted bleach soln without adding any acid though and get on fine.

Thanks, Andy. Yes I'd read about the nasty gases and associated precautions.

I think I'll leave the acid out and, like most people I'll probably get on fine

[jonnyt]

You can kill yourself easily mixing bleach and vinegar. I wouldn't even consider it even diluted.

[adomant]

bleach is a biocide and will sanitise on its own.(see the domestos advert) the only problem is the chlorine residue is destructive to yeast and beer flavour. to remedy this mix up some metabisulphate (campden powder) in a sterile water solution with a pinch of citric acid and rinse. bleach and vinegar with water mixed between is useful for rinsing lead away from brass thermowells and fittings, dont ever mix them directly.

[Graham]

Bleach or, more correctly, sodium hypochlorite is most effective at pH5. At that level 100% of the hypochlorite is present in the form of hypochlorous acid. It is the hypochlorous acid that is the powerful bug killer. Commercial breweries or any industry that uses hypochlorite as a disinfectant will adjust the pH of their solution to pH5 before use. It is still 97% effective at pH6; indeed anything around or below about pH7 is good enough.

Hypochlorous acid molecules have a neutral charge which easily diffuse through the cell walls of bacteria, thus getting directly to the heart of the matter, so to speak. This makes it several hundred times more powerful, and much faster than hypochlorite itself. It enables very low concentrations of just a few ppm to be very effective and the kill time is reduced to a second or two rather than tens of minutes. However, there is a snag. Dropping below pH4 causes a different reaction to take place, whereby the hypochlorous acid itself begins to be dissociated, evolving chlorine gas, which will come out of solution, so we do not want to go much below pH5. Gassing off the chlorine just makes the solution ineffective; one is unlikely to gas themselves or even notice the gassing off at the typical concentrations that we use.

[Morrisoff too]

Hi there

Just been looking into this bleach and vinegar malarkey.

Had a listen to the original Charlie Tally interview, where he says the pH for the vinegar/bleach solution needs to be about 8 at 80ppm, but then later agrees with Graham and says that commercial breweries use hypochlorite at pH5. Is that because they use straight hypochlorous acid rather than bleach? Is it possible to get a dilute vinegar/domestic bleach solution down to pH5?

Cheers

[Morrisoff too]

Just found this whilst searching for an answer. Seems to pretty much sum it up scientifically:

http://oregonstate.edu/dept/larc//sites ... -sheet.pdf

[hart5823]

I wondered if anyone had a good 'recipe' for this. I have seen 30ml thin bleach and 30ml white vinegar in 23L water numerous times as this is the suggested amounts from the inventor of starsan for a no-rinse bleach and vinegar soln.
. Only issue is that this is for US bleach which is specified at 5%, the thin bleach from British supermarkets is '>5%' ...
Just mix up at the US levels given that bottles are very clean as they are and just need a quick sanitize before having beer in them?