Darren, I'm a Molecular Biologist (Ph.D. in Biochemistry & Cell Biology) by trade.. but with no official microbiology major (other than being a Molecular Biologist and using various forms of E.coli and S.cerevisiae as my work tools). I wonder if you can help flesh out the Botulism point further -- not just from a NC perspective..
#1 Prevalence - is it out there, are we likely to encounter it here in Australia?
"http://en.wikipedia.org/wiki/Clostridium_botulinum" said:
Clostridium botulinum type A was found to be present in soil samples from mountain areas of Victoria.[22] Type B organisms were detected in marine mud from Tasmania.[23] Type A C. botulinum have been found in Sydney suburbs and types A and B were isolated from urban areas. In a well defined area of the Darling-Downs region of Queensland, a study showed the prevalence and persistence of C. botulinum type B after many cases of botulism in horses.
Sounds to me like it's soil borne on land and at sea.
#2 How can we minimise exposure to it, so it doesn't come into contact with our brew gear?
Don't brew on dirt or in the ocean. Keep dogs away... keep your brew area rodent-proof.
#3 How can we destroy it?
As far as I can tell, the only way to kill them is by Autoclave for 20min @ 121C..
I've emailed Five Star Chemical Co. to clarify, but I don't think any of their products will be active against Clostridium botulinum endospores. But I'll wait and see what they have to say about that.
#4 What situations in a brew house could anaerobic conditions be produced.
Wikipedia tells me that C.b. is isolated from samples with <2% O2. Does NoChill get O2 down to <2%? Could a blast of filtered air put enough O2 into NC wort to stave off any C.b. infection *and* avoid hot side aeration? What about fermenting wort? What is the % oxygen in a fermenting wort once fermentation has ceased?
#5 What regular practices in brewing would destroy it or inhibit its growth?
Obviously aeration of the chilled wort prior to fermentation will help, providing a significant infection/sporulation hasn't already happened.
I see this on Wikipedia, which has me wondering if we have little to be concerned about, but it is not referenced:
"http://en.wikipedia.org/wiki/Clostridium_botulinum" said:
Growth of the bacterium can be prevented by high acidity, high ratio of dissolved sugar, high levels of oxygen, very low levels of moisture or storage at temperatures below 3C (38F) for type A. For example in a low acid, canned vegetable such as green beans that are not heated hot enough to kill the spores (i.e., a pressurized environment) may provide an oxygen free medium for the spores to grow and produce the toxin. On the other hand, pickles are sufficiently acidic to prevent growth; even if the spores are present, they pose no danger to the consumer. Honey, corn syrup, and other sweeteners may contain spores but the spores cannot grow in a highly concentrated sugar solution; however, when a sweetener is diluted in the low oxygen, low acid digestive system of an infant, the spores can grow and produce toxin. As soon as infants begin eating solid food, the digestive juices become too acidic for the bacterium to grow.
NC and Chilled worts are high in sugar but without a reference from that Wikipedia entry for the above statement, I don't know what "highly concentrated sugar solution" actually means. That might be enough to inhibit growth, which would certainly help me sleep better at night because disinfecting it at home, sounds like an impossible mission.
Cheers for any additional insights..
