alking - 20-3-2016 at 11:54
I was simply curious about food preservatives and this had me wondering, I couldn't come up with anything doing some research. I know there are non
acidic preservatives in general, but not that I can find that would work for a sugary beverage without either ruining the flavor or having undue side
effects. I'm only talking about preventing biological activity, not taste or appearance preservation (though obviously the preservative cannot
significantly degrade these qualities or it would defeat the point), and only chemical means. In the same vein are there any biological preservatives
that may work? Yeast is the most common, but unless your 'sugary beverage' is alcoholic that's not much of an option. I'm not looking necessarily for
solely what's practical either so much as what's possible, it doesn't have to be something you can do at home or even on an industrial scale.
phlogiston - 20-3-2016 at 12:44
sodium benzoate
alking - 20-3-2016 at 12:58
Sodium benzoate is acid based.
edit: To elaborate, and correct me if I'm wrong, but while sodium benzoate is not acidic itself it increases the ability of an acid to permeate the
cell of pathogens and prevent their growth. In other words without an acid present it is not going to preserve anything.
[Edited on 20-3-2016 by alking]
aga - 20-3-2016 at 15:30
No it isn't : it's Benzene based, mostly, with a Na hanging around, kinda lost.
[Edited on 20-3-2016 by aga]
clearly_not_atara - 20-3-2016 at 18:08
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1152300/
Potassium sorbate is also used.
Pumukli - 20-3-2016 at 22:52
As far as I know they are either acids (acetic acid, lactic acid, propionic acid, salicylic acid) or the salts of acids (sodium benzoate, potassium
sorbate, sodium sulfite, etc.)
These salts are only effective at low pH, when there is chance to the free acid to form.
There is another class, the p-hydroxy-benzoic acid esters (Nipagins), which are supposed to work around pH 7 too. These are also "acid based" but
hydrolysis is not necessary for them to be effective. Some of these esters are banned in some countries but not all.
Tsjerk - 21-3-2016 at 04:07
Benzoate is perfectly active against microbes at neutral pH.
http://www.cibtech.org/J-LIFE-SCIENCES/PUBLICATIONS/2014/Vol...
What is wrong with acids by the way? I wouldn't call a weak acid at 10^-3 mg/ml in a close to nutral (Nutrient Agar/ Sabouraud Dextrose Agar, see
link) exactly acidic... these plates even are a bit basic (pH 7.5ish).
Also, if benzoate is acid based, phosphoric acid is base based 
[Edited on 21-3-2016 by Tsjerk]
alking - 21-3-2016 at 09:39
I haven't read your link yet tsjerk, but I will when I get home. That was how I understood it to work from researching it though maybe I am wrong.
Nothing is wrong with acid based preservatives, I was just wondering.
Aga did you read my edit? It was made before you posted so I don't see how you couldn't have. I'm not saying sodium benzoate is acidic, I'm saying it
requires acidic conditions to work effectively, thus it's bacterostatic activity is 'acid based' not the compound itself.
Tsjerk - 21-3-2016 at 23:57
Ok no problem. I don't know about the mechanism of action of benzoate, but I do know for example the protonophore m-chlorophenylhydrazone (CCCP) which
dissipates membrane potential, depending on protonation of the molecule. It does so however at neutral pH.
CCCP can pass the membrane while protonated and acts like a proton bridge over the membrane, hence abolishing the proton gradient and making
ATPsynthase losing its driving force (bad for any cell). Maybe benzoate does something similar.
phlogiston - 22-3-2016 at 01:12
Here is a recent PhD thesis on this subject, comparing the mechanisms by which various weak acids prohibit the growth of microorganisms:
http://dare.uva.nl/search?join=and;field2=keyword;field1=key... physiology of weak organic acid stress in Bacillus
subtilis;docsPerPage=1;startDoc=1
Apparently, some of these compound work as a proton uncoupler, interfering with oxidativ phosphorlylation like Tsjerk mentions, and others work by
lowering the the intracellular pH. Some do both.
There are numerous compounds that do these things, but for them to be useful in drinks there is ofcourse the additional requirement that they are safe
for human consumption. There is an ongoing discussion about some of these compounds, whether that is actually the case.
Spectrochemical order
morsagh - 22-3-2016 at 01:24
Hi, I can´t find some bigger spectrochemical order (where would be ligands like sulfate or COOH). Thank you for help.
Tsjerk - 22-3-2016 at 06:08
ATPsynthase will even start to work as a proton pump, using ATP as energy source to get the proton gradient back up again (any enzyme can work in
opposite direction, often less efficient though).
I used ATPsynthase knock out strains when I was looking at the effects of protonophores to exclude the ATP draining effect.
[Edited on 22-3-2016 by Tsjerk]
PHILOU Zrealone - 22-3-2016 at 15:44
High levels of suggar, erythritol, sorbitol, salt or a mix of those or whatever increases the osmotic pressure.