How much alcohol % is needed to halt biologiocal decomp. indefinitely?

[NeoPTLD]

Beer is around 5% and it gets moldy on standing. I guess wine turns into vinegar on standing from microbial activity.

Let's say you've got some fresh juice mixed with alcohol. What is the alcohol percentage needed to indefinitely halt microbial spoilage at room temperature in a tightly sealed container?(so alcohol wouldn't be lost through evaporation)

I couldn't find anything online..

 

[MadScientist]

There are certain wines, i.e., the madieras, that have an alcohol content of ~20%, and have a long shelf life. Indefinitely? What's your definition of indefinitely? These wines are fortified, (alcohol content increased), by the addition of brandies. They are are also heated and exposed to oxygen during the winemaking process.

The alcohol in a typical opened bottle of wine will start to oxidize into acetic acid (vinegar) sitting on the shelf within a few days to a week at room temperature.

Most liquors are ~40% alcohol by volume and do not have to be refrigerated. To be on the safe side I would not go any lower than this when mixing fruit juices, i.e., a screwdriver, with alcohol; and I would still refrigerate it due to any bacteria in the juice or the container.

 

[Pandamonium]

I didn't look up the study, but one of the senior scientists at a lab of mine told me there was an study that concluded that 20% EtOH is optimal for sterilizing lab surfaces/glass/etc. Granted this is for short term use.

In your example, if your fresh juice were pasteurized and the container came out of a dishwasher with a heated dry cycle (ie not towel dried or hand-washed), I'd say 20% would be okay for several weeks in a sealed container.

If you're a little looser with the requirements, I'd go with a higher alc. content. A lot of your hard liquors are good pretty much indefinitely, and they're around 40% EtOH.

It's kind of hard to tell though, because there are so many variables. If you took sterile juice (I'm talking fresh out of a pressure cooker sterile) and gave it a final alcohol concentration of 20% by volume in a well sealed sterile container, it would hold indefinitely. It might taste like crap after as the stuff in the juice breaks down, but it wouldn't give you food poisoning. But IRL you almost never see sterile, so I'd adjust real life usage to something like 30% for most cases, 40%+ if you want to be safe.

 

[Gibsons]

I didn't look up the study, but one of the senior scientists at a lab of mine told me there was an study that concluded that 20% EtOH is optimal for sterilizing lab surfaces/glass/etc. Granted this is for short term use.

Typo?

70% is what you usually hear, lots of things can survive a short dose of 20%.

If you're only looking to prevent microbial growth, anything over 40% is probably fine. If you want to preserve tissue structure and integrity of molecules, you probably want to go higher. You might get some dehydration artifacts wrt fine structural details, but nothing major.

 

[NeoPTLD]

I didn't look up the study, but one of the senior scientists at a lab of mine told me there was an study that concluded that 20% EtOH is optimal for sterilizing lab surfaces/glass/etc. Granted this is for short term use.

In your example, if your fresh juice were pasteurized and the container came out of a dishwasher with a heated dry cycle (ie not towel dried or hand-washed), I'd say 20% would be okay for several weeks in a sealed container.

If you're a little looser with the requirements, I'd go with a higher alc. content. A lot of your hard liquors are good pretty much indefinitely, and they're around 40% EtOH.

It's kind of hard to tell though, because there are so many variables. If you took sterile juice (I'm talking fresh out of a pressure cooker sterile) and gave it a final alcohol concentration of 20% by volume in a well sealed sterile container, it would hold indefinitely. It might taste like crap after as the stuff in the juice breaks down, but it wouldn't give you food poisoning. But IRL you almost never see sterile, so I'd adjust real life usage to something like 30% for most cases, 40%+ if you want to be safe.

Canned juice exist and they last almost indefinitely without alcohol. By indefinite, I meant not becoming bad in flavor, but halting microbial spoilage. i.e. meat stored in freezer goes bad because of oxidation and other break down, but last indefinitely in terms of food safe
ty.

 

[jagec]

Canned juice exist and they last almost indefinitely without alcohol. By indefinite, I meant not becoming bad in flavor, but halting microbial spoilage. i.e. meat stored in freezer goes bad because of oxidation and other break down, but last indefinitely in terms of food safe
ty.

But those are pasturized so that they have no living organisms in them, and then sealed. The OP is talking about adding alcohol to something which presumably has not been thus treated.

In my experience yeast is more likely to contaminate something sugary like juice, and it will self-ferment. The flavor is crap after too long, but bacteria doesn't grow...

 

[NeoPTLD]

But those are pasturized so that they have no living organisms in them, and then sealed. The OP is talking about adding alcohol to something which presumably has not been thus treated.

In my experience yeast is more likely to contaminate something sugary like juice, and it will self-ferment. The flavor is crap after too long, but bacteria doesn't grow...

What Pandamonium suggested is basically home canning.

 

[tcsenter]

As evidenced by the fact we use microbes to produce alcohol, alcohol is not really itself considered to be highly or even moderately antimicrobial. Primarily, alcohol kills germs during evaporation. You can use alcohol in solution to INHIBIT bacterial growth, but its not really good at killing many microbes except during evaporation.

 

[Gibsons]

As evidenced by the fact we use microbes to produce alcohol, alcohol is not really itself considered to be highly or even moderately antimicrobial. Primarily, alcohol kills germs during evaporation. You can use alcohol in solution to INHIBIT bacterial growth, but its not really good at killing many microbes except during evaporation.

High concentrations of alcohol are bactericidal for many bacteria. I don't think evaporation is necessary, the mechanism is usually explained as protein and membrane denaturation.

Depends on the bacteria, the surface, time of exposure, etc etc.. You probably won't kill many endospores, but normal vegetative bacteria can be killed.

Ye olde paper

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2059524/pdf/brmedj03844-0005.pdf

 

[CycloWizard]

A few things:
70% ethanol in water is used in labs because this formulation is optimal for breaking down cell membranes, as Gibsons mentioned.
Bacteria don't grow in juice because juice is too highly concentrated in sugar such that they can't grow.
I'm not sure what fraction of alcohol is needed to prevent growth. We usually use sodium azide for such things in the lab, but obviously you don't want to drink anything with any of that in it. I would speculate that the level required is between 10-20%, depending on the bacteria. There are likely bacteria that have been designed to survive above 20%, but these are obviously the exception.

 

[MadScientist]

I think we are getting a bit OT and forgetting the OP's question:

"Let's say you've got some fresh juice mixed with alcohol. What is the alcohol percentage needed to indefinitely halt microbial spoilage at room temperature in a tightly sealed container?(so alcohol wouldn't be lost through evaporation)"

Yes, sugar, as someone mentioned, in high concentrations, i.e., jellies, is a good preservative; but depending on the juice (orange, grape, tomato, lemon, etc.) the sugar concentration can vary greatly.

And even though it's to be sealed in a "tightly sealed container", the juice and container (sterile?) have already been contaminated with oxygen.

There are numerous references (Google them) that ethanol's maximum antimicrobial activity is between 60%-70% alcohol. I think that's already been established here.

Back to his question, everyone's just guessing, so let's experiment.

OP, as someone suggested, start by mixing your fruit juice with 10-20% ethanol by volume (vodka's a good choice) and let it sit at room temp (70-72F min) for 1 to 2 weeks, taste it, and get back to us.
Before you taste it make sure your medical insurance is paid up.

 

[BladeVenom]

10% alcohol and you might end up with vinegar. You already mentioned fortified wines which are usually around 20%, and keep better.

 

[MadScientist]

10% alcohol and you might end up with vinegar. You already mentioned fortified wines which are usually around 20%, and keep better.

I suspect the same, but it's an assumption not a proven fact. That's why I suggested to start at 10% alcohol to prove this.

 

[jimhsu]

Normal strains of S. Cerevisiae (considered ethanol tolerant given its use in industry) tolerate around 14%. http://www.springerlink.com/content/bl47322u0303x120/. No idea if higher concentrations simply inhibit growth, or actively kill. Again, 70% is good for lysis in MCB experiments.

Then again we thought everything died in boiling water, yet we know of bacteria that actually GROW at 121C (incidentally, it also freezes to death at 85C).

 

[PlasmaBomb]

Normal strains of S. Cerevisiae (considered ethanol tolerant given its use in industry) tolerate around 14%. http://www.springerlink.com/content/bl47322u0303x120/. No idea if higher concentrations simply inhibit growth, or actively kill. Again, 70% is good for lysis in MCB experiments.

Then again we thought everything died in boiling water, yet we know of bacteria that actually GROW at 121C (incidentally, it also freezes to death at 85C).

That's interesting...

 

[gsellis]

34%. I have a bottle I bought in Spain with this on the label "Wuzhou Ma Zong She Jiu". And the internet is strangely silient with only this:

Wuzhou Ma Zong She

"Wuzhou Ma Zong She Jiu". Liqueur asiatique à base de sorgho et de "lézard" titrant 34°. La bouteille contient 1 ou 2 lézards baignant dans le liquide jaunâtre...

The french says it all, but if you want it in english... it is 2 lizards in 34% alcohol I bought it in Estepona, SP at the Supermercado about 15 years ago. Those lizards are still doing fine in the bottle. Well as fine as they can be gutted and pickled.

 

[jimhsu]

121C is significant in that it is the typical autoclave temperature "guaranteed to kill all life" in medical waste disposal. Of course, now we know that is not the case...

 

[Gibsons]

121C is significant in that it is the typical autoclave temperature "guaranteed to kill all life" in medical waste disposal. Of course, now we know that is not the case...

As long as they aren't contaminated by bacteria from deep ocean hydrothermal vents, it should be okay. There's about a zero percent chance that they can cause disease anyway.

Actually their is one class of pathogen that can survive standard autoclaving, but it's not very infectious.

 

[jimhsu]

True, that's why you don't see lawsuits being flung around. These bugs die of hypothermia in humans anyways.

 

[Veramocor]

121C is significant in that it is the typical autoclave temperature "guaranteed to kill all life" in medical waste disposal. Of course, now we know that is not the case...

http://en.wikipedia.org/wiki/Hyperthermophile This bad boy can live for two hours at 130 degrees C

 

[NeoPTLD]

True, that's why you don't see lawsuits being flung around. These bugs die of hypothermia in humans anyways.

This isn't ATOT. What does this have anything to do with the original post?

 

[darkamulets]

And even though it's to be sealed in a "tightly sealed container", the juice and container (sterile?) have already been contaminated with oxygen.

Wouldn't boiling the product in a mason jar type setup cause all the air to be pushed out of the jar and kill anything left behind?

 

[MadScientist]

Wouldn't boiling the product in a mason jar type setup cause all the air to be pushed out of the jar and kill anything left behind?

We're back to canning. Boil it before or after you add the ethanol? If after you are going to boil off the ethanol.

OP, where are ya. Have you tried any juice/ethanol combos yet?

I'd say skip the 10% and try 20% ethanol/juice mixture first, since madiera wines (~20%) have a long shelf life at RT.