I think you can take heart with the Botulism argument - in the fact that at high temperatures the HDPE is quite permeable to oxygen. One of the reasons to squeeze out the air.. its getting quite enough oxygen contact through the material of the cube, without extra from the headspace. All you need to do is limit it a bit when the wort is hot enough for your traditional Hot Side Aeration to occur - As the wort cools down enough to actually absorb 02, the hdpe is still so permeable to the gas that the wort is far far from anerobic enough to be an issue.
I don't have figures to back this up (I am in the research phase of obtaining them)... but lets put it this way. Would you have a botulism concern if you put your hot wort into an open Carboy filled to the top (heated so it didn't shatter) closed with a bit of tinfoil?? Not sealed, just loose like a starter. I'm guessing no-body would have issue with that.
But - how much oxygen is actually making it through the couple of square inches of surface wort? None through the sides because glass is not permeable. Transfer rates of gas through liquid interfaces are pretty low without agitation. But I still doubt anyone would worry. Whether they should or not is a different question.
Now compare that to a sealed cube - sure, there is no actual liquid to air interface... but you have better than a square meter of surface area, which is Atransmitting oxygen at 58cc per square meter per 24hrs per mm of thickness at 25C - At 35C this rises to 111cc. Who knows at higher temps. After a couple of days at 25C - a standard cube might as well be in an open bucket from an oxygen levels perspective. Its saturated. And our cube has had a flying head start at higher temperatures while it cools down.
If anyone has better transfer rate figures, or can tell me what the transfer rate of oxygen across an undisturbed liquid/gas interface might be. That would be great. I am also hunting the levels of oxygen needed to inhibit Botulism spores.
I strongly suspect though I don't know for sure - that your sealed cube is actually as safe or safer than an open bucket made out of glass or stainless would be.
OK here's a blast from the past.
In the late 70s I ran a home brew shop in Queensland and the standard fare was Brigalow kits, Pride of Ringwood pellets and flowers, a big honey dispenser of Malt Extract and a similar dispenser of Glucose syrup on the counter, and shelves full of airlocks, finings etc. The good old days. Then in 79 a wonderful thing happened. Coopers of Adelaide decided to go into Home Brew and what they did was to package the actual brewery wort into cubes and ship it out. That's right, the genuine wort of Sparkling ale and Stout and you could brew it at home, from the 23 litre five gallon imperial cubes. And they were cube shaped, not jerries.
I brewed quite a few and they were spectacular. Later they replaced the cubes with a plastic bag in a box. Freight, obviously, killed that model so they went into 'normal' home brew tins from the early 80s.
Cubes are tried and tested for over thirty years, shipped for thousands of kilometres in all temperature conditions. Floats my boat.
I dont use a tap
I just pull the cap off and up end it into the fermenter
The risk of air leaking in through the tap worries me a bit
I don't know about Coopers or other places, but when MHB used to get a lot of the NNL fresh wort kits, they often arrived quite warm, suggesting they were hot packed. Also at a HAG brew day we used the Potters brewery and did a big batch of oktoberfest, all hotpack no chilled. I didnt ferment mine for 18 months or so (yeah the one I mentioned earlier) - turned out to be a ripperBut we don't know that Coopers hot packed that wort. They may well have rapid chilled and packed the cooled wort in a sanitary way. Hard to do as a homebrewer - breweries do that sort of thing all the time though.
Me too!Why isn't it a problem?? Convince me
Back then science was basically just alchemy, it's a different story now day what with the scientific method and all. The point is that there is no doubt that botulism can be produced in these conditions, just that it isn't likely.I think those not willing to try new things, or are adverse to change may be the nay sayers. I was a little skeptical to start with expecially reading about the dangers of botulism etc. However tried it once, and again and again and find it to be a quick and easy alternative to immersion chilling.
Obviously if the science told be that it was a bad thing, it would be a little late. I also believe the Earth is round, not flat as scientist once proclaimed.
As I understand it the 'botulinum' spores' growth is inhibited in acidic solutions. With wort PH generally being between 4.8-5.6, and anything below 7.0 being considered acidic I would conclude that wort would be a hostile environment for botulinum spores.
Me too. I worry it might EXPLODE if the tap is in there.
Seriously, tho, I like them undrilled. Less gaps for botulism to lurk between batches.
I don't know about Coopers or other places, but when MHB used to get a lot of the NNL fresh wort kits, they often arrived quite warm, suggesting they were hot packed. Also at a HAG brew day we used the Potters brewery and did a big batch of oktoberfest, all hotpack no chilled. I didnt ferment mine for 18 months or so (yeah the one I mentioned earlier) - turned out to be a ripper
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pH has to be below 4.6 to stop botulism, even that sometimes isn't enough, and 4.8-5.6 certainly isn't. At least this convinced me that was the case.
I sometimes use a tap in mine so it's easy to drain into my fermenter
Unless they are putting a sediment reducer on it to filter out the break and hop material.
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