"Off Aroma" across multiple beers

[byronyasgur]

I have done about 10 beers or so; and while they're getting better with practice there's an off aroma in most of them which is really bugging me. I have no frame of reference is the problem - I've read a lot about off flavours and aromas but I can't get to the bottom of it - I was hoping that some people might comment on the likelihood or unlikelihood of the candidates - guesswork I know, sorry, since nobody can taste my beers - obviously it's all a bit of a shot in the dark but any thoughts would be appreciated - a problem shared is a problem halved

I haven't really done proper taste notes on the beers really but in general this phantom aroma is diminishing through successive batches - though I don't really know what I'm doing to effect that change. So far I've done a couple of of IPAs, a couple of pale ales and a couple of wheat beers ( strangely while the first wheat beer was a bit of a disaster for other reasons its the only one that doesn't suffer from this problem at all ... go figure ) that and a small batch of cider I did

The biggest problem is I literally can't describe the aroma - it's driving me nuts I've thought about it for months and while I totally recognise it I can't put my finger on it - or worse I can't really even compare it to anything - none of the stuff I've read really rings a bell and worse again there's about 5 or 6 things that sort of "could" be it - see below but I mean it might be fusel alcohols, it might be dms, it might be astringency ...

Another difficulty I'm having - maybe someone can help with is that in the earlier beers I could taste this as an off flavour but the last couple I can't taste it but I can smell it clearly and it ruins the dry hopping - but most of the off flavour/aroma material i've come across is to do with taste not aroma


The Candidates

• Fusel alcohols - I don't have a fridge but I am careful with temperature and rarely if ever do my ferments get higher than manufacturers instructions ( US-05) especially in the first few days
• Infection - I don't know this one really pickles my noodle - I am full on OCD about sanitation and cleaning so I don't see how all the batches would be infected but I have no way to know how sanitary things have to be - and I thought I'd recognise an infected batch I'm very sensitive to bad tastes
• High mash ph - I really thought it could be this and I spent a lot of time in brew and water and now I use RO water with some salts ( mainly going for tasty's hoppy water ) at this point - I noticed an improvement when I switched from what I had been using ( sometimes bottled, sometimes filtered tap water, sometimes well water - none of them tested but all of them tasted fine ) ... but even with the improvement it's still not right.
• Chlorine in the bottles - I used VWP in the dishwasher for bottle wash and sterilisation as recommended by a few people - I was not sure about it I thought I could still detect the chlorine smell and taste from the bottles after the wash - I now think this might have affected 2 batches ( making them astringent ) but my last batch I didn't use VWP on the bottles and though I didn't get the taste I can still get the off aroma so I don't know how this could be the culprit
• DMS - there's a possibility it might smell like cooked corn but I have yet to sit down with a beer and some cooked corn and compare - what type of corn do people mean - we have mainly tins of sweetcorn here in Ireland but there's not a big smell off them - not sure how I'd set up a test and I do pay attention to things like leaving the lid off and I haven't done any really short boils or anything - still this is the one I'm "liking" for the crime lately - but I thought DMS wouldn't be a problem given that I'm doing ales, 60 min or longer boils and leaving the lid off.
• Beer not ready - maybe I'm just not waiting long enough - mainly I'm waiting 3 weeks after bottling ( having carbed at room temp ) .... I thought that would be enough for at least getting rid of off flavours and aromas

I hope this post isn't just boring ranting, asking the impossible - any thoughts or comments appreciated

 

[JLeuck64]

No it's not boring at all! We live for helping other home brewers like yourself figure out how to fix a problem so you can make the great beers you deserve. I've read enough of these types of requests to know that we're going to ask you to describe your process (brew day) to the letter so get ready to bare your soul to the internet ( ;

Seriously though, describing your process will make it easier for those that chime in to recognize what might be going wrong for you. So bare with us and be prepared to wade through all the comments/opinions to follow. Eventually we'll get you back on track.

 

[McKnuckle]

It does sound like a chemical issue, since the flavor is no longer there with successive brews but the aroma is. That can be indicative of a lower concentration of the same offensive component.

Although you do use RO water now, so chlorine would seem to be out of the picture.

But I'll also offer this; your water profile - which I'm familiar with from brewing Janet's Brown Ale - has 350 ppm SO4, 110 Ca. While some people are fine with that level of sulfate, it's very high, and it's not going to work well in all beer styles.

I'd eliminate that variable from your brewing for a while. Add less gypsum - only enough to keep the SO4 level under 100, and Ca at a minimum of 40 ppm. McDole's profile isn't "hoppy" - that's a misnomer - the SO4 makes it dry and, to some, astringent at that level. There's also a requirement to use Epsom salts (boosts Mg and SO4) to achieve his profile, which I would avoid entirely.

Just my opinion... I also build my water, but I'm much more conservative about the mineral content.

 

[RM-MN]

The temperature at which you ferment has a great deal to do with aromas in your beer as does the yeast you use and the length of the fermentation. As others have mentioned you need to tell all.

 

[John Eberly]

Of all the millions of flavors and odors that can be sensed you want us to guess which one you're dealing with? There is no way to answer your question except with a long list of "maybes".

Find a few friends in this wide world and have them taste your beer and say what they think it tastes/smells like. There's no substitute for the palate. It sounds like you have good senses but you are just not making the connection from your nose to your memory.

 

[byronyasgur]

I've read enough of these types of requests to know that we're going to ask you to describe your process (brew day) to the letter

The temperature at which you ferment has a great deal to do with aromas in your beer as does the yeast you use and the length of the fermentation. As others have mentioned you need to tell all.

So for preps I make sure I have ice for cooling, RO water collected ( in a plastic fermenter ) , all the ingredients, recipe, and a yeast starter if I'm doing one.

• Then before I mash I do the water salting
• I weigh the grains while the strike water heats up. I have two 9 litre pots in which I do BIAB ( not ideal as it's a lot of extra work and I'm planning on getting a single 33 litre pot or something )
• I stir in the grains and hit the mash temp.
• I do both pots staggered by around 20-30 minutes - I do both the exact same ( I divide everything in half so everything is the exact same ) - so I'll just describe one process until I get to the fermenter
• Then I put the lid on and wrap the pot in a large towel to keep the heat up. I usually come back every 10-15 minutes and check the heat - usually giving it a bit of heat while stirring and pack it back up again
• So I normally do a single infusion 60 min mash but I've done mash outs a couple of times too making the mash 70mins
• Usually through the mash I'm weighing the hops. I put these in muslin bags. I add irish moss at the 10/15 min mark
• Then I lauter the grains by lifting the bag and putting an old cooling rack under it
• because I'm at such a low volume I typically add 2-3 litres across both pots to bring up the boil volume so I can hit a batch volume of 12litres in the FV ( of RO salted water ) - I tend to pour this over the bags rather than into the kettle after lautering - I squeeze the bags a bit to get as much wort out as possible, though the last day I think I got much higher than expected efficiency so I don't think I'll bother that much as it's a bit of a nuisance and I'm busy enough with 2 pots anyway
• I start the boil - lid off
• add the hops at the appropriate times ( usually 60m 10m and FO)
• At the end of the boil I put the pot in a sink of cold water and add ice around it, stirring occasionally with a sanitised paddle - keeping the lid on throughout
• I fish out the hop bags after prob 10 minutes - usually I think I'm down to less than 80c within about 5 or 10 minutes
• I used to chill the wort down to pitching temp but the last couple of brews I just got the first kettle down to about 30c and the second one to about 50c and ( having taken extra care in sanitising the FV ) I sealed it up and pitched the yeast the next morning as recomended by a few people on HBT
• take OG and record
• The fermenter is a plastic 30litre drum
• I sanitise with starsan mixed at 8ml to 5litres using RO water - I drain the foam after a minute or 2 contact time - though when not adding the yeast till next day I have the FV sitting with starsan in it for an hour or so - I spray starsan all around the edges, even the outside and handles etc - I have a spiggot on the fv and i take it apart and put starsan through every part of it
• Ive used us05 yeast on every batch so far but for a kolsch which is still in FV. I would pitch at around 18c and try to keep the temp below 20c which I usually manage esp on the first few days - it might have got up to a max of 21 or 22 c but I dont even think it has gotten that far on most of the more recent brews
• I keep the fermenter covered from sunlight and I never open it except for dry hopping which I'd take extreme care with sanitation over
• I usually bottle after 2 weeks

 

[byronyasgur]

But I'll also offer this; your water profile - which I'm familiar with from brewing Janet's Brown Ale - has 350 ppm SO4, 110 Ca. While some people are fine with that level of sulfate, it's very high, and it's not going to work well in all beer styles.

I'd eliminate that variable from your brewing for a while. Add less gypsum - only enough to keep the SO4 level under 100, and Ca at a minimum of 40 ppm. McDole's profile isn't "hoppy" - that's a misnomer - the SO4 makes it dry and, to some, astringent at that level. There's also a requirement to use Epsom salts (boosts Mg and SO4) to achieve his profile, which I would avoid entirely.

Just my opinion... I also build my water, but I'm much more conservative about the mineral content.

yes I was wondering about this actually - I was always considering if what I was tasting/smelling was astringency but I'd never heard that SO4 could make it astringent - can astringency have a smell as well as a flavour ?
I'd be quite happy to use the "safest" profile that I could at this stage as I'm very new to this - I only bothered with the water and salts because I felt the water might have been the problem - I'm glad I got the RO system - but for now I'm really just trying to make good beer not "great beer" as Palmer would say .... would you have a profile you'd recomend ? - I think the next beer I'm doing is my second try at this one ( which turned out great first time but did have that aroma slightly https://www.homebrewtalk.com/showthread.php?t=470698 - I notice in his post he said he used this profile not sure what you'd think of that

Calcium : 113
Chloride : 38
Magnesium : 0
Bicarbonate : 86
Sodium : 32
Sulfate : 221 
PH : 5.4

edit - looking at it now it's got pretty high sulfate too ... I really don't know much about what I should be shooting for at this point - so much to learn :-(

 

[Dcpcooks]

I would not put bottles in a dishwasher. You've got food particles stuck in a closed loop, bad idea.
Cleaning is removing organic matter with oxy clean or PBW. Rinsing is removing the cleaner. Sanitized is the addition of acid to remove 99% of bugs, star San is not a cleaner. This is how you should clean everything that touches your beer after the boil.

Your making water additions and you need to be sure your making them correctly. What amount of gypsum and CaCL are you adding to your RO water? I agree with McKnuckel keep it small and keep it simple. If you haven't yet, read the water primer in the brewing science section. It sounds like your adding a lot of CaCL to your water. It's a tricky chemical as it's hydropholic. It will absorb water from the air and make it challenging to measure accurately. So your sulfate may be higher than what you think they are.

How are you collecting your RO water?

How do you determine that your yeast has finished cleaning up after itself? I.e. What's your procedure to determine fermentation is complete?

If I had to guess:

You may benefit from a little more time on the yeast cake.
You may want to review your water salts additions and the "hardness" you are adding to the water. You can make a great IPA with a pinch of gypsum and a pinch of CaCL and a nice hop schedule.
I would not clean my bottles in a household dishwasher.
You may want to try another yeast. Have you used the same yeast every batch? Maybe you don't like the yeast's aroma? It's like terroir to wine. Yeast puts its stamp on everything!

Edit: you want to control fermentation temps going forward! ( I mean no disrespect, you have jumped in and done a very good job of it so far) . So plan for that as a priority going forward. I think you said rarely do I exceed recommended temps in the first few days. If I got a do over it would be to spend all my money on fermentation control. I wish I had adopted that earlier in my brewing. As the New President (sic) would say it's yuuuuuuggggge! It's the greatest. Everybody loves my fermentation control.

Cheers

 

[Dcpcooks]

And don't squeeze you grain bag

 

[TheMadKing]

And don't squeeze you grain bag

Nonsense advice. Squeeze away.

 

[JLeuck64]

The temperature at which you ferment has a great deal to do with aromas in your beer as does the yeast you use and the length of the fermentation. As others have mentioned you need to tell all.

I would second this. I too have had some bad tasting beers after fermenting in a store room that got a little too warm. My store room has a heater so I can control temps well enough through the winter months but during the summer months it wouldn't stay cool enough. Once I realized that was the culprit I re-purposed an old fridge to make a ferm chamber. Wow, did that make my beers taste great throughout the summer! I set my ferm chamber up to both cool and heat with a home built temp controller after reviewing several threads on HBT. Now days you can purchase the same thing for next to nothing and if you're lucky enough to get a used fridge for free then it's definitely time to add this piece of equipment. I've seen a lot of others on HBT report how adding temp control to their process was the single most improvement to the quality of their beer. I would have to agree with them from my own experience.

Sounds like you've got a handle on water, congrats! That was the last part of my process that I tackled and it was a steeper learning curve for me.

 

[McKnuckle]

Your fermentation temps don't sound concerning at all to me. It's roughly 64-71F for those who haven't done the conversion. For US-05, 68-70F is perfect and produces no off flavors.

I have three questions:

First, you are using Bru'n Water to figure out salt additions. What g/L or g/gal values of gypsum, CaCl, and Epsom are you adding, and what is the estimated mash pH?

Second, how does the beer smell/taste before you bottle it?

Finally, what kind of plastic is this 30L drum you are fermenting in? Food grade (I hope)? If you put your nose in it, does it have an odor?

 

[RM-MN]

So for preps I make sure I have ice for cooling, RO water collected ( in a plastic fermenter ) , all the ingredients, recipe, and a yeast starter if I'm doing one.

• Then before I mash I do the water salting
• I weigh the grains while the strike water heats up. I have two 9 litre pots in which I do BIAB ( not ideal as it's a lot of extra work and I'm planning on getting a single 33 litre pot or something )
• I stir in the grains and hit the mash temp.
• I do both pots staggered by around 20-30 minutes - I do both the exact same ( I divide everything in half so everything is the exact same ) - so I'll just describe one process until I get to the fermenter
• Then I put the lid on and wrap the pot in a large towel to keep the heat up. I usually come back every 10-15 minutes and check the heat - usually giving it a bit of heat while stirring and pack it back up again
• So I normally do a single infusion 60 min mash but I've done mash outs a couple of times too making the mash 70mins
• Usually through the mash I'm weighing the hops. I put these in muslin bags. I add irish moss at the 10/15 min mark
• Then I lauter the grains by lifting the bag and putting an old cooling rack under it
• because I'm at such a low volume I typically add 2-3 litres across both pots to bring up the boil volume so I can hit a batch volume of 12litres in the FV ( of RO salted water ) - I tend to pour this over the bags rather than into the kettle after lautering - I squeeze the bags a bit to get as much wort out as possible, though the last day I think I got much higher than expected efficiency so I don't think I'll bother that much as it's a bit of a nuisance and I'm busy enough with 2 pots anyway
• I start the boil - lid off
• add the hops at the appropriate times ( usually 60m 10m and FO)
• At the end of the boil I put the pot in a sink of cold water and add ice around it, stirring occasionally with a sanitised paddle - keeping the lid on throughout
• I fish out the hop bags after prob 10 minutes - usually I think I'm down to less than 80c within about 5 or 10 minutes
• I used to chill the wort down to pitching temp but the last couple of brews I just got the first kettle down to about 30c and the second one to about 50c and ( having taken extra care in sanitising the FV ) I sealed it up and pitched the yeast the next morning as recomended by a few people on HBT
• take OG and record
• The fermenter is a plastic 30litre drum
• I sanitise with starsan mixed at 8ml to 5litres using RO water - I drain the foam after a minute or 2 contact time - though when not adding the yeast till next day I have the FV sitting with starsan in it for an hour or so - I spray starsan all around the edges, even the outside and handles etc - I have a spiggot on the fv and i take it apart and put starsan through every part of it
• Ive used us05 yeast on every batch so far but for a kolsch which is still in FV. I would pitch at around 18c and try to keep the temp below 20c which I usually manage esp on the first few days - it might have got up to a max of 21 or 22 c but I dont even think it has gotten that far on most of the more recent brews
• I keep the fermenter covered from sunlight and I never open it except for dry hopping which I'd take extreme care with sanitation over
• I usually bottle after 2 weeks

This might be the cause. I'd try to get the wort down to 15-16C to pitch the yeast and keep it under 17. Some people report peach aroma keeping it this low but I've not noticed it in my beers, Higher temps, especially in the early stages of fermentation, allow the yeast to make esters that most of us think are undesirable. If you don't have active temperature control your yeast will cause the temperature of the beer to rise. As the temperature rises the yeast work faster which causes the temperature to rise. You may not notice this rise unless you are monitoring it closely and this is where a lot of off aromas arise.

For a simple control, put your fermenter in a tub of water. That alone will make a difference as it will absorb and help dissipate the heat the yeast make. Adding ice to the water will help more.

 

[byronyasgur]

Edit: you want to control fermentation temps going forward! ( I mean no disrespect, you have jumped in and done a very good job of it so far) . So plan for that as a priority going forward. I think you said rarely do I exceed recommended temps in the first few days. If I got a do over it would be to spend all my money on fermentation control. I wish I had adopted that earlier in my brewing. As the New President (sic) would say it's yuuuuuuggggge! It's the greatest. Everybody loves my fermentation control.

Cheers

thanks - and thanks for the other ideas too I'm taking it all in - no actually I meant over all the brews I think it got over the high temp maybe once maybe twice - so Yea I do reasonably good temperature control and I don't really see how it could be the MAJOR issue on all the brews but I literally can't wait to get a fridge I'm on the lookout - thought I'd get a free old fridge but they're like hens teeth in Ireland for some reason - I'll prob just save up and buy a new one - even secondhand ones are hard enough to get - but I was guessing that what you said would be the case so thanks for the encouragement - I'll peruse that ASAP

 

[byronyasgur]

First, you are using Bru'n Water to figure out salt additions. What g/L or g/gal values of gypsum, CaCl, and Epsom are you adding, and what is the estimated mash pH?

I worked with dosing 18.56L of RO water with : gypsum 8.5g, Cacl 0.5g: Epson Salts 3.7g

Second, how does the beer smell/taste before you bottle it?

Interestingly I forgot to mention it didn't really seem to have the that much wrong with it before it went in bottle but it's hard to tell because it's got a green taste - however my last brew over the last couple of days I think the smell has died out so much that I can barely get it - but one of the others are well aged at this point and it's very prominent - both as a taste and a smell - I'd almost at this stage think that it was to do with my water salting but it's funny you ask this question about before bottling because like I said it didn't really seem to be there before bottle conditioning - so ???

Finally, what kind of plastic is this 30L drum you are fermenting in? Food grade (I hope)? If you put your nose in it, does it have an odor?

yes food grade standard plastic bucket fermenter - something like this - https://www.google.ie/search?q=home...UICCgB&biw=1440&bih=685#imgrc=G8G2cJS0LAkUDM:

Odour - yes - my experience is that all plastic has an odor - am I wrong - especially if you wash it out with very hot water - I did have some problems when using just warm water with the smell of the previous batch hanging around but the really hot water gets rid of that but there's that plastic smell which I don't like too much - though AFAIK it seems to be something that plagues people who ferment in plastic a bit - but I didn't think it would be a major off flavour/aroma issue ... but ???

 

[byronyasgur]

This might be the cause. I'd try to get the wort down to 15-16C to pitch the yeast and keep it under 17. Some people report peach aroma keeping it this low but I've not noticed it in my beers, Higher temps, especially in the early stages of fermentation, allow the yeast to make esters that most of us think are undesirable. If you don't have active temperature control your yeast will cause the temperature of the beer to rise. As the temperature rises the yeast work faster which causes the temperature to rise. You may not notice this rise unless you are monitoring it closely and this is where a lot of off aromas arise.

For a simple control, put your fermenter in a tub of water. That alone will make a difference as it will absorb and help dissipate the heat the yeast make. Adding ice to the water will help more.

good tip - I had wondered about this detail, thanks - will take it into consideration

 

[JordanKnudson]

I worked with dosing 18.56L of RO water with : gypsum 8.5g, Cacl 0.5g: Epson Salts 3.7g

My thought is that Epsom salts can create an odd sort of sour taste if the proportion gets too high. I have ceased using it entirely (as one previous poster suggested here) after learning a bit more about my water, and I think my beer has only improved as a result.

Other thoughts on what may be causing your off-flavor...

1. A usual suspect is oxidation. When you described your process, you didn't mention much about how you make the transfer to the bottling bucket and what your bottling day looks like (understandable, these being rather incidental in the brewing process). If you're introducing too much oxygen at either of these points, the result could be what many people describe as a "papery" or "wet cardboard" flavor and aroma in the final product. I've had some oxidized beers, and while I understand these descriptors, it also has a quality that is unique and defies my vocabulary. This could also explain why you're only noticing it in the bottles.

2. Perhaps the taste of the yeast itself? US-05 is an okay flocculator, but if much of the yeast is still in suspension (or simply gets poured out into the glass, even if it has flocculated well in the bottle), you'll be able to taste it. And yeast tastes...well, yeasty. But not necessarily in a bready sort of way...more of a weird bite, that in my experience gets in the way of hop and malt flavors.

That's all I can think of at the moment, aside from what everyone else has been saying.

 

[byronyasgur]

My thought is that Epsom salts can create an odd sort of sour taste if the proportion gets too high. I have ceased using it entirely (as one previous poster suggested here) after learning a bit more about my water, and I think my beer has only improved as a result.

Other thoughts on what may be causing your off-flavor...

1. A usual suspect is oxidation. When you described your process, you didn't mention much about how you make the transfer to the bottling bucket and what your bottling day looks like (understandable, these being rather incidental in the brewing process). If you're introducing too much oxygen at either of these points, the result could be what many people describe as a "papery" or "wet cardboard" flavor and aroma in the final product. I've had some oxidized beers, and while I understand these descriptors, it also has a quality that is unique and defies my vocabulary. This could also explain why you're only noticing it in the bottles.

2. Perhaps the taste of the yeast itself? US-05 is an okay flocculator, but if much of the yeast is still in suspension (or simply gets poured out into the glass, even if it has flocculated well in the bottle), you'll be able to taste it. And yeast tastes...well, yeasty. But not necessarily in a bready sort of way...more of a weird bite, that in my experience gets in the way of hop and malt flavors.

That's all I can think of at the moment, aside from what everyone else has been saying.

thanks for those thoughts too - yes my bottling process is fairly standard - and I'm careful with O2 - but I suppose it's a bit of a skill and it's easy to put a bit of O2 in the bottle by accident - I think I'll just put a ton of O2 into one of the bottles on purpose as a test case next time and see what effect it has so I'd recognise the flavour - wet cardboard aroma is not unlike the aroma - it's possible of course that I have a number of smaller issues rather than a single large one and not being experienced I still have to figure out these smells and tastes.
I used WPL029 in my last beer ( a Kolsch) so I'll prob experiment with that with an ale too to see if it's the yeast taste that I'm picking up

How long does it take before the O2 affects the beer do you know ... and does it diminish during the conditioning process - just so I know when to taste it at the worst time for the test case

 

[Kharnynb]

if 05 is the problem, you can always try danstar nottingham for a similar yeast with a more "english" profile.

 

[McKnuckle]

Actually, oxidation doesn't diminish during conditioning. The opposite is true: It can take a little bit of time before the staling becomes apparent. This is easier to experience when kegging, because you can sample the beer on draft fairly quickly, and it may seem fresh... then suddenly, a bit down the line it tastes dull, and you wonder what happened. With 2-3 weeks of bottle conditioning, the oxidation is nearly always apparent by drinking time.

I find that oxidation is more of a risk when the beer is opened or transferred multiple times. A single exposure event, such as the bottling process, rarely oxidizes my beer into the perceptible range. But the times I have handled it in an overly attentive manner - taking multiple samples, pulling lids/airlocks, racking - are the times it has suffered the most.

 

[byronyasgur]

I find that oxidation is more of a risk when the beer is opened or transferred multiple times. A single exposure event, such as the bottling process, rarely oxidizes my beer into the perceptible range. But the times I have handled it in an overly attentive manner - taking multiple samples, pulling lids/airlocks, racking - are the times it has suffered the most.

I have a tap on the front of the fermenter for samples and I don't do secondary so aside from bottling the only other time it's open is for a few second to throw in dry hops
I often wonder about headspace though - there's a lot of confusing stuff I've found about it - some saying about a blanket of CO2, some saying this is a well known myth. My fermenters are 30 litre and I do 12 litre batches. I wonder is this something to consider?

 

[McKnuckle]

There should be a blanket of CO2 present in the headspace as long as the primary fermenter is airtight, and as long as the beer is not cold (the CO2 will absorb more readily into the liquid at that point). I don't think there is a problem with headspace given a standard 2-4 week primary. It's secondary where headspace must really be kept to a minimum, since any protective CO2 in the primary will off-gas during an open transfer.

 

[spittybug]

Unless I missed it.... how long and how hard are you boiling your wort?

 

[JordanKnudson]

I have a tap on the front of the fermenter for samples and I don't do secondary so aside from bottling the only other time it's open is for a few second to throw in dry hops
I often wonder about headspace though - there's a lot of confusing stuff I've found about it - some saying about a blanket of CO2, some saying this is a well known myth. My fermenters are 30 litre and I do 12 litre batches. I wonder is this something to consider?

There should be a blanket of CO2 present in the headspace as long as the primary fermenter is airtight, and as long as the beer is not cold (the CO2 will absorb more readily into the liquid at that point). I don't think there is a problem with headspace given a standard 2-4 week primary. It's secondary where headspace must really be kept to a minimum, since any protective CO2 in the primary will off-gas during an open transfer.

+1 ^^ You do have a huge amount of headspace, but assuming that you have a relatively normal primary fermentation and keep it sealed (which it sounds like you do), that shouldn't be the issue.

The CO2 "protective blanket," however, is a notion that has only hung around because it makes sense in a very superficial way -- CO2 is heavier, ergo it sinks and keeps a barrier between the beer and the oxygen. Unfortunately, while it is true that CO2 is more dense than oxygen, the conclusion drawn from that information is incorrect. If you open your fermentor, the gases will mix and mingle, as it were, and while you won't instantly lose all of your CO2, you *will* introduce some oxygen, which you will then close up in your fermentor with the beer. Depending on the conditions (how long was it open, is fermentation complete or not, etc.), you may or may not see a noticeable effect from this.

I had another thought, as well, about your off flavor. What is the water that you use to make priming solution? That was a variable that I overlooked very early in my brewing career, and screwed up some good batches simply by making my priming solution with bad (i.e. chorinated) tap water.

 

[byronyasgur]

Unless I missed it.... how long and how hard are you boiling your wort?

usually 60 mins - I did a couple of 90min boils one was for a Kolsch using pilsner malt

strong rolling boil I'd call it - though usually a bit gentler for the first 10min or so as I'm close to boiling over with the hot break

 

[byronyasgur]

I had another thought, as well, about your off flavor. What is the water that you use to make priming solution? That was a variable that I overlooked very early in my brewing career, and screwed up some good batches simply by making my priming solution with bad (i.e. chorinated) tap water.

thanks - yes I had thought of that - I use RO water for that

 

[byronyasgur]

Thanks for all the comments everyone. It really is the best forum in the world when you can ask totally open ended questions like mine and effectively get free consultation from a bunch of experts!!! burp ... !!!

Seriously though I have a lot of information now and thoughts to go forward with and hopefully get to the bottom of this. I really hope to be able to repay the generosity but I'm sure most of you are way ahead of me at this point but there's always another nutter who wants to get into homebrew that I can help when I get my own act together.

I'm tending to think the comments on water salting sound like they might be the most relevant in my particular case, though the oxygen pickup is something else to consider, and there were many other ideas in there like yeast etc . For those talking about temperature control I am actually purchasing a fridge tomorrow so looking forward to that ( found a lot of people recommending a F fridge over a worth chiller so going that route )

Thanks again all - any more comments welcome but I just wanted to take a minute to say thanks to the community.
:fro:

 

[botigol]

On your temperature measurement, did you measure the temperature of the beer or the area in which your fermenter sits?

 

[byronyasgur]

On your temperature measurement, did you measure the temperature of the beer or the area in which your fermenter sits?

no just a stick on lcd strip

 

[botigol]

no just a stick on lcd strip

That's close enough to beer temp that the issue shouldn't be the fermentation temperature.

Just a shot in the dark, because it is an aroma that some people don't recognize, except in high doses, by chance does the off-aroma smell like bananas?

 

[byronyasgur]

Just a shot in the dark, because it is an aroma that some people don't recognize, except in high doses, by chance does the off-aroma smell like bananas?

No I don't think it does - I wondered a bit about that actually because a couple of my beers were wheat beers and a one or 2 of others had a bit of wheat in them ... but no I don't think it's bananna or fruity at all -- I'm tending to think it's the aroma of astringency if there exists such a thing - but the wet cardboard one is also a possibility I suppose - it might be more like wet dog - or so I though last time - gross thought I know but it's an aroma not a flavour ( or I wouldn't be drinking it )

 

[whovous]

Try simplifying your salting. The numbers that really matter are sulfate, chloride and calcium. Make sure these come close to your chosen profile. It is perfectly OK if magnesium, sodium and bicarbonate are all zero. If you go this route you may wind up salting your RO water with only gypsum and calcium chloride.