time+temp Killing beer bugs

[beermaker]

Looking for a chart with temperatue and time for killing lactobacillus and brettanomyces, any info will be apreciated.

Michael Lalli
choc Beer Co.
Krebs, OK

[Woolsocks]

I haven't ever found such a thing, but the rule I've heard more than once is that 80°C for 15 minutes is enough to be considered "sterile". If you search for "pasteurization units" on this forum, you'll find a way to quantify how much killing you're doing, but I still don't have the numbers for how many lacto/pedio will survive after x min at y temp. If you find better info, please share.

[wiredgourmet]

Graphs here: http://www.foodsci.uoguelph.ca/dairyedu/TDT.html

If you've got infected lines, seals, gaskets, vessels, etc., or a sloppy process, those are problems you need to attack specifically. Otherwise, these organisms should not be much of a concern.

Heat treatment isn't done on a sliding scale; there are various approved regimens for pasteurisation, and one normally chooses from among them. No one wanders about in the gray areas between them, hence the scarcity of scales and graphs.

Brewing is special because true pasteurisation is chiefly concerned with pathogens that don't incubate in beer due to its low pH and its hop acids that above, say, 15 IBU, are fairly toxic to Gram-positive bacteria such as lacto and pedio (acetobacter is G-neg however).

Brett, pedio, lacto, and aceto all tolerate a low pH quite well, but lacto and pedio don't tolerate hop acids well. That leaves brett and aceto as the main candidates for heat treatment, assuming that there is no infection in the system, no sloppy practices, etc.

162 F for 15 seconds conforms to the HTST pasteurisation regimen recognised by most regulatory bodies. This can be hard on flavour. Furthermore, pasteurisation doesn't destroy spores: brett's sporulating twin, dekkera, is unlikely to be affected.

While not recognised as true pasteurisation, 145 F for 30 minutes, followed by rapid cooling, is widely regarded as adequate among "low risk" foods, of which beer is one. Indeed, 145 F (63 C) for 10 mins is probably good enough for beer. You only need a more aggressive regimen if you have a high bacterial/fungal load to begin with (infection, dirty brewery), or if you are trying to achieve shelf stable beer for a year or more. If you are a good brewer in a clean facility, your bacterial and fungal loads should be very small to begin with.

Pasteurisation is not sterilisation: the goal is to reduce the fungal and bacterial load to a point regarded as safe (or not detrimental to quality) throughout the product's anticipated shelf life by killing 99.999% of the reference product's unpasteurised load. The lower the load to begin with, the better it all works.

Remember that heat-treated beer is just like hot wort: it will enter the same temperature danger zone so that a tiny population of bad guys can infect it unless it's cooled very quickly. I often wonder if the additional handling doesn't cancel out the benefits. I suppose doing it makes people feel better.

Sterilisation can be achieved by UHT pasteurisation (250 F for 1 second) which is devastating to the flavour of most foods. For liquids, sterile filtration (1 micron), which also is devastating to flavour in most cases, is an alternative to UHT pasteurisation.

Choose your poison.

Now, as an aside, why would you wish to destroy some of the tastiest fermentation organisms known to brewing?

For further reference: http://www.foodsci.uoguelph.ca/dairy...urization.html

[Moonlight]

Great info!
This is for killing creatures in beer. If you were to simply use the same time/temps for massive metal objects like filters, bottlers, or heat exchangers, consider that the high temp to kill must occur at all possible spots- not just at some random thermometer at some spot in the flow that reaches that temp. The nooks and crannies that will be the last to heat up will be the best refuges for colonies of nasties to wait out the thermal storm and will come out to play when the temp is more to their preference. And they will just laugh.

[JoeV]

Product vs. equipment?

I am not sure if the original question is a Product pasteurization one or an equipment Heat sanitization isssue. Product pasterurization is pretty well established as mentioned. Does anyone have any information on heat sanitization of equipment. Some brewers have told me boiling water is even insufficient and you need steam. I boil my carbonation stones and run boiling water throught my heat exchanger (both sides) for at least 30 minutes as a santizing step. It works great but I wonder if I could get away with less?

[wiredgourmet]

That's a very good point. You have to go above boiling to destroy spores. Whether or not you *need* to is another issue, and opinions vary. My opinion is that if you work clean and take care, you probably don't need to sterilise religiously unless there is evidence of an infection. I'm certainly not advocating this, just expressing a personal bias. Clean gear is not sterile, but it gives microfauna very little to work with.

For sterilising small items, a large pressure cooker or pressure canner is handy (poor man's autoclave). A contact time of 5 mins is effective at 252 F (122 C), which occurs at about 15 psi. You will increase the time depending on the item's mass, naturally, so that it is hot throughout.

Saturated (i.e. "wet") steam is also very effective, btw.

Dry heat is far less effective. You need to hit 320 F (160 C) for about 2 hours to achieve the same effect.

Chemicals are more convenient and economical -- although contact is an issue for asymmetrical little gadgets, seals, gaskets, valves, etc.

There's been a lot of debate on the issues and practicalities of sanitising gear here on the boards. And it seems that there is no ideal solution. http://www.probrewer.com/vbulletin/s...archid=1018219

I assumed the original post was about pasteurising beer, but I was wondering if it might be about something else entirely. I have used brett and lacto to inoculate small batches that I would pasteurise and blend with larger batches. The idea was to cultivate the bugs in their preferred environments and then kill them so they wouldn't continue fermenting after their addition to the main batch. Perhaps this is the direction the thread was meant to take.

PS, that link expired shortly after I posted it. I did check it, but it only worked for a while.

[dick murton]

From memory, lacto is about as sensitive to heat as brewing yeast. Not sure about bretts - as have never seen any info.

But as a guide - 20 minutes at 80 C minimum is commonly used - though people generally actually use 85 C, e.g KG filters. For keg rackers or yeast propagation plant vessels for example they use steam - kegs are steam sterilised using water saturated steam for around 30 seconds, bigger tanks, ofter gross overkill at 20 minutes. As mentioned in one of the other answers, probably found by searching this site, it is the release of the energy of vaporisation as the steam condenses that gives sufficient thermal energy to kill off the bugs.

We use steam for sterilisation of gas filters and associated systems - 10 to 20 minutes saturated steam

Other than that - agree with the other answers - though not totally sure about using dairy data, but I haven't looked at this link yet.

Cheers