Any microbiologists here?

[sao123]

Wife is a microbiologist and a forensic scientist. She agrees the autoclave is the way to go.

She says 60C is enough to kill off yeast, they are easiest to kill off.
Most molds are killed of at 84C.

However, spore creating bacteria (C Botulinum) are the challenge, as the spores can survive in temperatures up to 100C to 116C depending on Ph and Aw.
Generally more acidic Ph = Lower temp to kill the spores.


Instead of sterilization, you might consider pasteurization...
UHT -> 138C for 2 seconds.

 

[linuxboy]

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.

Pasteurize it (legal standards for log 5 as in CFR 21 p 133, or legal-ish through cheaper heat exchanger as HTST can be expensive) and you should be fine. Low motility in syrup. Only zygosaccharomyces even stands a chance among the yeasts as saccharomyces usually has poor osmotolerance. Your concern should also include plan for post-treatment risk prevention to avoid contamination. EG pump system and SSOP for the connection, backflow prevention, etc.

Also re pathogenic bacteria. Is a concern. Not only about bacteria, also about toxins they may produce.

 

[CoachB]

I'm curious...corn syrup is a common food industry product. It is common to see rail cars full of the stuff in transit as well as tanker trucks for local delivery. Logically, contamination/spoilage concerns would have already been addressed by the industry. Either your application is unusual or your client has unrealistic expectations??
Additionally, my experience in the water industry tells me that without a persistent disinfectant, long term sterility is very, very difficult especially in situations where there is constant product turnover.
My $0.02

 

[CZroe]

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

Found it:
http://forums.anandtech.com/showthread.php?t=2227820&p=33038338