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Why not ferment in boil vessel?

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The LODO guys would tell you not to expose the nearly finished beer to any O2, and I think they would be right. If you look at breweries like Bell's, they go to great pains to keep DO to infinitesimal levels when they are bottling beers to be bottle carbonated. They know that when you feed small concentrations of sugar to yeast (as opposed to the large amounts in a yeast starter or in a fresh full batch of wort), the yeast are going to eat it, but not do much, if any, dividing. So they don't need O2 to build cell wall materials in preparation for the budding they won't be doing.

While O2 demand is highest in the replication phase, there are some papers that have investigated depressed yeast going back into aerobic respiration in the presence of O2 which breweries can use to accelerate a sluggish fermentation. With the pathways and conditions unclear for a yeast cell to switch back to aerobic, that’s why it’s a bit of guesswork. No harm for the OP to give it a go and see, but if it doesn’t work out, there wouldn’t be a whole lot of information to suggest what to change to get the O2 scrubbed without making a more specific science experiment out of it.
 
Some guys do just dump everything into the fermentor. Anvil sells a kit to allow you to ferment in their kettle. It’s been done.

I read a post within the past a week claiming the person wound up with an unusually clear batch of beer and the only difference was they dumped all the trub into the fermentor.

Long lag times/slow cooling have traditionally been frowned upon. More opportunity for contamination. The idea is to minimize the time between the end of the boil and the time you get your yeast in and established. I think there may be one or more other ill effects that have been traditionally thought of as being related to slow cooling.

Far as putting plastic wrap between kettle and lid, the gas produced does need to escape. That’s why everybody has 14 or 15 airlocks laying around.

It was mentioned earlier in this thread - don’t buy into that “CO2 is heavier than air and creates a blanket that displaces oxygen” belief. That has been disproven over and over again.

The biggest downside I see is tying up your kettle.
 
I ferment in a SS stockpot with loose fitting lid - even worse I open it on day 2 and day 3 to skim and remove the head - even worser no temperature control - it gets wusserer - I bottle using the jug and funnel method - on the bright side many of my beers are tasted by the head brewer of a local microbrewery who likes them a bit and offers advice where applicable - struggling at the moment with hopstands - I added 100 gm mosaic pellets to 22 litres of wort at 75 deg C, removing them at 50 deg C - beer is still too bitter - 5 gm of summit for 60 minutes the bittering hop.....
 
I have brewed on and off since 1995. I do not brew competitively. My beer falls reasonably clear as I use Omega British Ale VIII in 1.044 to 1.060 bitters. SRM runs from 8 to 12. Whenever a good selection of imported bitters get pushed out of the grocery store, I make beer. In the 90's it was wine coolers. Now it is the alcoholic Kool Aid that is taking ove.
I started brewing close to the same time as you.

There was Bartles and James wine coolers everywhere and then they came out with Zima.

Later, it became Mike’s hard lemonade and Not Your Father’s root beer.

Now its all White Claw, Truly and a thousand others trying to copy them. Jack Daniels is bottling Lynchburg Lemonade and punch and other sweet drinks. I heard Zima was coming out again for some anniversary.

History repeats itself.

People can get way too obsessed with oxygen. Back when we started brewing, we made good beers and nobody was writing articles about being obsessed with oxygen. In fact, people told us our yeast needed oxygen and they sold little CO2 cylinders and diffusion stones so we could add oxygen.

Where I think much of this O2 obsession comes from is the creation of NEIPA and all these guys who don’t use any hops until they throw 12oz into the kettle at flameout. Oxygen seems to really affect these beers and the oxygen obsession lines up perfectly with the rise of NEIPA and guys who want to drink beer that looks like it was scooped out of a mud puddle from a dirt road next to an Amish farm.
 
Yeast needs oxygen at the beginning of fermentation to multiply and be healthy. The rest of the time yeast does not need oxygen but will scavenge it for you. Wort never needs oxygen. That about sums it up.

Edit - also, hops are destroyed by oxygen.
 
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One other thing to be considered with no chill - your hops are remaining in the hot wort longer, as you are not chilling. So that should be taken into consideration and how it will affect final IBU.
 
I fermented in my boil kettle a couple of brews ago and it went just fine. I broke several rules that would make most on this thread cringe and in the end I had great clear beer that lasted for over 2 months.

I didn't seal my lid, in fact I put my temperature probe in the beer between the lid and the lip of the kettle. My kettle doesn't have a spigot so I siphoned off the yeast cake (after 2 weeks fermentation) with an auto siphon into the keg that wasn't purged. Both containers wide open.

So my advice is to go for it and my only point of caution would be about style dependence. I'm sure my technique wouldn't work for a neipa. That being said there are a lot of open fermenters used by professionals for heffeweizen Czech lagers etc. Mine was a brown ale and was great.

IMG_20201029_191104_222.jpg
 
One other thing to be considered with no chill - your hops are remaining in the hot wortit will affect final IBU.
Great point. This batch could easily be out of balance. I will likely blend it with something later if that is the result. In future I will make much later hop additions. That is the kind of fact based info I like about this forum. Thanks again.
 
Yes, but remember, open fermentation is not really about oxygen exposure or trub etc... Open fermentation begins when the yeast need a lot of oxygen. Then the yeast naturally protect themselves/beer by making the krausen layer which is a barrier. So in the end, not much is different with an open ferment until you get closer to final gravity. Which is why German breweries move the beer with active yeast on to spunding to scavenge the O2 pickup along the way.

So to me, if you were going to ferment in a boil kettle and the lid was not super tight, it would only matter when you were approaching final gravity. So it would be wise to spund if you were fermenting in the boil kettle. Otherwise you would be transferring still beer into kegs/bottles. The real gain would be to have a fermenter that one could also lager and serve from. Then you would be saving some time and never exposing the beer to any O2.
 
Anchor, Trumer and Samuel Smith all use open fermentation. I'd like to try it some day. My Dad used to open ferment in a 10 gallon crock with a towel pulled over to top back in the 1960's. Smelled great!
 
I"ve done it with my Digiboil and LalBrew Voss. I've even used the Digibrew to maintain the fermentation temp (which is quite high with Voss). This vessel heats from below so if there is a lot of trub that can interfere with heating. Also, I do "no chill" without a cube. Ive put plastic wrap over the top between the lid and the vessel and have also omitted that step. No apparent difference. Your yeast needs to be ready to go is what I have found makes the most difference. I had no problems but I would consider siphoning some of the trub before fermentation. I like cloudy beer. So that potential result doesn't bother me. Also, I do many of my fermentations open (with only a brew bag over the top) like some of the best commercial breweries. If you are trying something new, make it a one to three gallon brew the first time. Try anything that you want if you can't really answer the question "why not?" to your own satisfaction. This is especially true if the technique saves time.
 
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I tried fermenting in the boil kettle about 3 years ago when it was suggested by @Miraculix. I've been using this method ever since. 76 batches without issue. I use a stainless hop spider to keep the hops and other boil additions (e.g. orange peel) out, but everything else stays in for the entire fermentation. I have not noticed any off flavors or yeast related issues even on "light" beers. With 1 teaspoon of gelatin after the keg has been chilled down, I get crystal clear beers. I do use a silicon hose that has been slit and bonded together for a lid seal and about 20 one inch binder clips to keep it closed and air tight. 1/2 hole in the lid with a silicon grommet for the airlock and you're all set.

Give it a try. You'll likely get used to washing 1 pot once after the batch is bottled / kegged (assuming you're BIAB).

~HopSing.
 

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