[kiowes]

I soak my towels, which I use for one week, taking daily showers, in a white vinegar solution of 500ml in 14 litres of tap water.

I measured the pH of the white vinegar (Acetic Acid : 4.5%) before adding any water, where it remained until it turned pH4-5 around the five litre mark, and then to pH5 at 8 litres.

I only soak the towels in an acid bath (vinegar), washing the vinegar away in a short water only cycle in the washing machine, followed by a bicarbonate of soda rinse to remove the oils and balance up the towels pH.

I read that hydrogen bonds holding together strands of DNA break up at high pH (alkaline), but I also understood that low pH (acid) can neutralise pathogens such as Escherichia Coli (E. coli), Salmonella and Listeria Monocytogenes, so which bath should I place the towels in : acid or alkaline ?

Before, using commercial soap powder, I found that it wouldn’t take long for a smell to develop on my towels, and that was because the perfumes in the powder were only masking the odour, and the remaining bacteria ate them and the resulting poo was the smell. With the vinegar soak I found that the smell would not return i.e. the bacteria would be neutralised, so what is going on ?

I can only imagine that the bacteria on my towel must have been neutrophile, or alkaliphile ?

It seems that pH 5 is enough to kill them over the course of a 10hr+ soak, but I would like to know what bacteria they are to be sure that an alkaline bath is best to neutralise them, at what pH and for how long - how do I begin to figure this out ?

[Corribus]

The only way to know for sure is culture the bacteria and then use a variety of analytic methods to classify. Of course, you are assuming it is only bacteria, likely also fungi are present. All of which, by the way, in most cases aren't harmful.

As you guess, each organism has its own pH viability range. Detergents and cleaning temperature also make a difference. So does the community makeup (i.e., biofilms, etc.). And whether you're killing them, inactivating them, or whatever is also a matter of uncertainty. But short of doing cultures it's hard to know what is there, what you're killing, and so on. Besides, as soon as your towel becomes wet during use, you're growing organisms again. And the microbiological makeup may change each time, depending on season, local conditions, and what your skin ecology is at any given time.

Microbiomes are complex. Sounds to me like you're overthinking it.

[rolnor]

If you wash at 90°C you will get rid of the smell.

[kiowes]

I never wash above 40º, I don't just wash towels.

I find that for my personal clothing (pants and socks) and towels a vinegar bath works well enough to avoid having to use a commercial option.

How do I go about classifying cultures, I suppose that I would need to send samples off to a laboratory, what about Amazon, is there a home kit I could use ?

[Corribus]

So you wash your towels in cold water with no detergent and only diluted vinegar, and you wonder why you arent killing off microorganisms?

[rolnor]

You need sterile equipment in a labb to do this and you have a mixture of many bacteria+funghi, its really a very strange thing alltogether to be doing. Just wash your towels separat att 90° with normal detergent, it can really not be to hard.

[kiowes]

Put you hand under 40º water and tell me that is cold water. 90º temperatures have adverse affects on some textiles, so vinegar is a far safer solution to managing bacteria.

What can normal detergent do that vinegar cannot, it cannot be both acid and alkaline at the same time. I am trying to find out a method that I can use to test for the measure of vinegar I need, and to test if it is working.

[wildfyr]

What's so wrong with soap? Soap is much more lethal to bacteria than vinegar. It breaks up their cell walls. I think many bacteria can grow just fine in 500 mL vinegar in 14L of water. heck, vinegar is a food source for some bacteria.

And who gives a crap what the pH of your bath towels are after drying... they work just as well at pH 6 as at pH 8.

To a bunch of scientists your cleaning method is very odd.

[Corribus]

I'm no microbiologist, but consider:

The pH of your solution I estimate to be in the range of 3-3.5 depending on how strong your vinegar is. E. coli can survive several hours (without growth) at pH down to 2. (Reference: https://www.nature.com/articles/s41467-020-15350-5). This makes sense because you can still get sick from eating pathogenic e.coli, even though they get exposed to stomach acid at pH 1-2. Once they pass to small intestine, where pH is higher, they start to grow again you're done for. Of course, you're speaking as though you know which bacteria are there and responsible (or that bacteria are the problem in the first place), but it's safe to generalize here: Microorganism lifecycles are not binary (dead or not dead), they go dormant under adverse conditions, then grow again when conditions change. Using vinegar might be enough to pause bacterial growth, but it probably isn't enough to kill them, even if you use pure vinegar, and even if you soak them for hours. It isn't even close to sufficient. Enough survive, you're back to exponential growth again after you put your clean towels back in the humid environment of your bathroom.

There's a reason people use detergents and hot water. Most odor-causing organisms have not evolved to deal with strong detergents, which rapidly lyse cell membranes.

(Regarding textile quality - agreed, the washing process damages textiles. In my experience, mechanical agitation and the high heat of the dryer is far worse for textiles than detergents, though. And water hardness impacts how soft they feel after drying. Use a delicate cycle (cold water, low agitation, low spin speed), or hand wash, and dry over low heat (or air dry) if you want your textiles to last longer. This will preserve your textiles far better than going without detergents.

[Borek]

What can normal detergent do that vinegar cannot, it cannot be both acid and alkaline at the same time.

pH is not the only parameter that is important here. Soaps and detergents contain strong surfactants which are much better at destroying the lipid bilayers (that the bacteria cell walls are mostly made off) than the low or high pH solution is.

[kiowes]

What's so wrong with soap? Soap is much more lethal to bacteria than vinegar. It breaks up their cell walls. I think many bacteria can grow just fine in 500 mL vinegar in 14L of water. heck, vinegar is a food source for some bacteria.

And who gives a crap what the pH of your bath towels are after drying... they work just as well at pH 6 as at pH 8.

To a bunch of scientists your cleaning method is very odd.

My understanding of is that a protein molecule covered by a protective layer of lipid (fat) can be broken down with Bicarbonate of Soda, just as with soap. I give the washing a second separate rinse after the vinegar wash, to remove the oils and anything else.

The reason I am testing the pH is to see how far it is diluted in the water, and with the understanding that certain bacteria perish (or become disabled) at certain pH levels, that measure was a good point to begin testing to see what was actually going on.

You're quite emotional for a scientist. I'm not here for that.

[Borek]

My understanding of is that a protein molecule covered by a protective layer of lipid (fat) can be broken down with Bicarbonate of Soda, just as with soap.

Then your understanding is wrong.

Not even sure why you refer to a "protein molecule covered by a protective layer of lipid". Is that your bacteria model?

I give the washing a second separate rinse after the vinegar wash, to remove the oils and anything else.

Water rinse doesn't remove oils. Earlier you stated your second wash is with bicarbonate - it doesn't remove oils either. At best it neutralizes the acetic acid.

The reason I am testing the pH is to see how far it is diluted in the water, and with the understanding that certain bacteria perish (or become disabled) at certain pH levels, that measure was a good point to begin testing to see what was actually going on.

As you you were told (but decided to ignore), while some bacteria can be killed by the pH change, most won't be bothered much with pH changes that won't destroy your towels.

Sorry, but your approach doesn't make much chemical nor biological sense.

[kiowes]

The model I had in mind was that of a virus, different to bacteria perhaps, but I don't know much about that.

The idea was that the vinegar would kill the bacteria, and the bicarb would remove the oils. And no, I'm not going to use them at the same time so they cancel each other out.

The towels are soaked in White Vinegar over night, which mostly gets washed away in a washing machine cycle. Then the towels are washed in a second cycle with Bicarbonate of Soda (not soaked), perhaps I didn't make that second phase clear enough.

I can assure you that oils definitely do get washed away with the Bicarbonate of Soda. I use a bicarb wash my hair i.e. my scalp, and can definitely confirm that it does remove oils, there's no doubt about that in my mind.

Contrasting towels with my bed sheets, I noticed that they smelt musty after the vinegar soak method and a bicarb wash i.e. not clean. But after a second attempt, this time soaking them in a bicarb (pH 9-10) bath, the result was that the musty odour was banished, which must have been oil based ? So for bed sheets it makes more sense to use bicarb, as body oils will most likely be in contact with them, whilst towels mostly deal with water, after the oils have been washed away during the shower.

I was compelled by the heat based argument, but it cannot be applied universally, and worrying about which solution to use for which garments adds complexity. Even if the bacteria are only disabled by the vinegar, as with towels, which I can confirm do stop smelling with a vinegar bath, that should be reason enough to do it because who wants a smelly new towel ?!

Perhaps I could wash the towels in a 90º wash, but would I then need anything other than water, if the bacteria is killed in the heat ?

You say that pH doesn't matter, but I have proof that towels stop smelling with a vinegar bath, and bed sheets with a bicarb bath, so something must be working.

In order to be sure, I was thinking about artificial UV light exposure, as I cannot guarantee strong sunlight, after the garments were dry. This I am sure will kill the bacteria, but in that event is there any need for a hot wash, or any vinegar/bicarb, or even soap ?

[rolnor]

Virus has no metabolism so they cant produce smell.
Could you att least try to wash at 90°C with detergent? I think you will be happy with the result.

[kiowes]

I've used detergent on all my clothes all my life, until the last few years.

I could try 90º, but that would only be for a few garments, and even then would I need the powder ?

Anyway, I can see that you're all out of patience, which is a real shame. I thank you for your help. But I shall move on.