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headmaster

Cube Sour™

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Some craft breweries simply sour the beer with 88% lactic and skip the trouble, doesn't take much, for eg, to sour to 4.5 I needed about 13ml, to sour to 3.3 I think I calculated 28ml, not even a nip. 

But they say it's akin to microwaving a steak. No complexity whatsover, which probably translates to a very boring drinking experience

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19 minutes ago, headmaster said:

Leaving 23 litres of sugary wort at 40c for a day or three could be quite risky as some of the bad bacteria would find that to be a good holiday destination!

which is why i bring it to a boil and then cube it. oh well, see how i go.

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1 minute ago, Ben 10 said:

which is why i bring it to a boil and then cube it. oh well, see how i go.

Good point, quite possibly this cube method may well be so much more sanitary than the kettle sour, that you really don't need to do the pre-acidify step. I had a bottle of lactic, and quite cheap and easy to do it for me I guess. 

Your lacto source ideally would need to be sterile, like the capsules. If using yakult or yoghurt maybe less so, although these will be below 4.6 in ph anyway.. 

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I guess the problem lies with cracking open the cube to add the lacto at sub 50c temps, being temps where contamination can occur. theoretically posing a risk. 

Because this is a bit of a new frontier, I don't want to take any chances. 

Botulism poisoning is so rare it might be jumping at shadows though... 

If botulism is active, and then the ph drops below 4.6, it will kill botulism spores, but the toxins from the botulism actually remain in the liquid, it's not like the drop in ph eradicates the toxins. 

I don't know what the subsequent boil would do to those toxins, that would be interesting to know actually. 

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https://www.fsai.ie/faq/botulism.html 

Does cooking kill Cl. botulinum and its toxin? 
Normal thorough cooking (pasteurisation: 70°C 2min or equivalent) will kill Cl.botulinum bacteria but not its spores. To kill the spores of Cl.botulinum a sterilisation process equivalent to 121°C for 3 min is required. The botulinum toxin itself is inactivated (denatured) rapidly at temperatures greater than 80°C . 

 

So that may mean that if contaminated, the spores may survive the boil, but not the toxins. 

Next to find out what PH the spores can tolerate

Edited by headmaster

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From here:  https://www.who.int/news-room/fact-sheets/detail/botulism

C. botulinum will not grow in acidic conditions (pH less than 4.6), and therefore the toxin will not be formed in acidic foods (however, a low pH will not degrade any pre-formed toxin). Combinations of low storage temperature and salt contents and/or pH are also used to prevent the growth of the bacteria or the formation of the toxin.

 

 

So in theory, if it grows in the cube sour, because you have not adjust ph to 4.5, then it may form toxins and spores. the toxins will be denatured in the boil, and the spores will no longer grow once the ph drops below 4.6. Maybe they will be killed by the ph drop as well. 

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