Any microbiologists here?

[Howard]

Can someone tell me if what (range of) temperatures should be used to sterilize osmophilic yeast strains, e.g. Zygosaccharomyces, Saccharomyces, etc.

 

[MagnusTheBrewer]

Can someone tell me if what (range of) temperatures should be used to sterilize osmophilic yeast strains, e.g. Zygosaccharomyces, Saccharomyces, etc.

Boiling (212 f.) for thirty minutes.

 

[shortylickens]

Get a home autoclave.

 

[Rakehellion]

I'm not a microbiologist, but I am a microbe. Ask me anything.

 

[William Gaatjes]

Ask Gibsons.

 

[alzan]

I think zinfamous is a microbiologist.

 

[Cappuccino]

Why don't you ask your lecturer?

 

[PlasmaBomb]

Autoclave is the way to go - 121C for 30 minutes?

 

[Ichinisan]

I think zinfamous is a microbiologist.

Yeah. Really really micro. Molecular even.

 

[Ruptga]

Immerse in liquid tungsten, that always does the trick for me.

 

[Mr. Pedantic]

Some fungal spores aren't autoclave-able. For fungi that infect humans, heating at around 80C for 30 minutes should kill everything.

 

[linuxboy]

Standard sterilization process applies here with autoclave.

Are you looking for a lethality curve instead of straight sterilization guideline? n log reduction per specie/strain?

 

[Printer Bandit]

Any mycologists here?

 

[Howard]

Why don't you ask your lecturer?

Man, every time I ask a technical question it seems someone has to be as clever as you.

I've been out of school for many years and am now in industry, thank you. This question pertains to a practical application of a corn syrup storage and processing application.

 

[Howard]

Boiling (212 f.) for thirty minutes.

To this and a few answers along the same line: high temperatures (over approx 60 degrees C is my guess) are not acceptable due to colour change of the corn syrup. I'm looking for more of a log 5 reduction, or maybe even log 4; the micro limit on the manufacturer's TDS is quite low. The QA department of the client hasn't expressed the need for absolute sterility. To be honest, they're not 100% on their particular needs...

I believe that a long-term holding temp of 57 degrees C is enough to pasteurize most everything, but there are some spoilage bacteria/spores/yeast that may survive this, hence the question. As for pathogenic bacteria, they are not a concern as the final product comes to near-boiling temperature.

The primary concern is that the syrup does not spoil or ferment while in storage. A full turnover of the tank may happen 1-2 months. There will be germicidal air conditioners for the tank head space to control post-loading contamination... and other details I don't necessarily need to go into just now.

 

[Gibsons]

Saccharomyces will survive ~minutes (if that?) at 60C. I'm assuming vegetative (growing) cells. Schizo is probably similar. If they've stopped growing and are in stationary phase, they'll likely be harder to kill.

How long you need to heat depends on how many you have to start with, what media they're in etc. i.e. If your media is acidic, they'll probably die much faster.

Should be very easy to test...

 

[Gibsons]

I believe that a long-term holding temp of 57 degrees C is enough to pasteurize most everything,

I suspect this is correct wrt saccharomyces.

Clostridial spores would be another matter.

Thermophiles would of course survive, but I doubt they're of any concern.

 

[Howard]

I suspect this is correct wrt saccharomyces.

Clostridial spores would be another matter.

Thermophiles would of course survive, but I doubt they're of any concern.

We're on the right track, I think.

We don't need to worry about any non-sporulating pathogenic bacteria as they will certainly be wiped out at >90 C for over 15 minutes, and the two big ones, salmonella and e. coli, are not supposed to be in this stuff at all.

Sample TDS:

Microbiological Characteristics:
Bacteria/g <100
Mold/g <20
Yeast /g <20
Coliforms/g <10
E.coli/30g negative
Salmonella sp./100g negative

The pH is roughly 4.8, which unfortunately is not low enough to inhibit botulinum. I have to assume the syrup will be an anaerobic environment as there is no recirculation of the syrup within the tank. Worst case for the treatment of botulinum spores is to run the syrup through an inline thin-film UV filter, I suppose.

Again, the main concern is to prevent any spoilage of the syrup in storage. This means controlling yeasts, molds, and spoilage bacteria.

 

[fralexandr]

I took introductory microbiology, microbial ecology, and food microbiology in college.

typical food safety involves storing cooked food at temperatures either below 40F (4C) or above 140F (60C).
These temperatures are meant for preventing or at least greatly slowing growth of most food related microbes (Most of the ones that can grow in those ranges aren't food health related).
Cold slows down chemical/cellular activity, in general, so any organisms that can grow in extremely cold environments will do so slowly.
Heat can denature proteins, but there are some proteins that are stable to relatively high heats.
Microbes are capable of "building" up a limited tolerance to temperatures if given enough time to acclimatize.
One of the reasons why pasteurization and flash freezing work so well.

Why not just store the corn syrup in a really cold freezer?

if the water content can be reduced further, that might be a good way at slowing/preventing growth.

autoclaves are probably best, but somethings can't be autoclaved.

Zygosaccharomyces lentus
http://www.ncbi.nlm.nih.gov/pubmed/10583679
Some Zygosaccharomyces can grow at 4C apparently

C botulinum survives in the corn syrup as a spore right? So there shouldn't be any issues with growth (not enough water content).

 

[Howard]

I took introductory microbiology, microbial ecology, and food microbiology in college.

typical food safety involves storing cooked food at temperatures either below 40F or above 140F.
These temperatures are meant for preventing or at least greatly slowing growth of most food related microbes.
Cold slows down chemical/cellular activity, in general, so any organisms that can grow in extremely cold environments will do so slowly.
Heat can denature proteins, but there are some proteins that are stable to relatively high heats.
Microbes are capable of "building" up a limited tolerance to temperatures if given enough time to acclimatize.
One of the reasons why pasteurization and flash freezing work so well.

Why not just store the corn syrup in a really cold freezer?

if the water content can be reduced further, that might be a good way at slowing/preventing growth.

autoclaves are probably best, but somethings can't be autoclaved.

Zygosaccharomyces lentus
http://www.ncbi.nlm.nih.gov/pubmed/10583679
Some Zygosaccharomyces can grow at 4C apparently

C botulinum survives in the corn syrup as a spore right? So there shouldn't be any issues with growth.

The syrup needs to be kept at 48C minimum, otherwise it thickens up too much to be easily pumpable.

 

[fralexandr]

Is the syrup stored in a diluted form? There's not much you can do if you're limited to <=60C . Are you allowed to add lots of salt? hah

various extremophiles that probably don't matter, but cover most of the things that limit growth.
http://www.nhm.ac.uk/research-curation/research/projects/euk-extreme/

Is it safe to use UV light? Hmm I guess not. Something about furans from fructose or something.

 

[Howard]

Is the syrup stored in a diluted form? There's not much you can do if you're limited to <=60C . Are you allowed to add lots of salt? hah

various extremophiles that probably don't matter, but cover most of the things that limit growth.
http://www.nhm.ac.uk/research-curation/research/projects/euk-extreme/

Is it safe to use UV light? Hmm I guess not. Something about furans from fructose or something.

No, the syrup is stored as it comes from the tanker, and no, it's not diluted.

Salt cannot be added.

UV light is safe, but costly for this application.

 

[biostud]

Autoclave is the way to go - 121C for 30 minutes?

This.

I'm also a real microbiologist Although with focus on genetics and bacterial resistance.

 

[Ichinisan]

This.

I'm also a real microbiologist Although with focus on genetics and bacterial resistance.

I'm a fake microbiologist. Focus on icky and gross.

 

[CZroe]

Paging Texashiker (I hear he has a plan for eliminating AIDS).