# Harsh hop bitterness



## welly2 (21/5/16)

Trying to get to the bottom of a bitterness issue I've been noticing in my beers. Read this on reddit and wondered if there's any truth to it:

"One thing I see a lot of with bad homebrew IPA is that guys will cold crash their carboys to get the hops to fall to the bottom before bottling/kegging. This will cause oxidation that can be perceived as excessive bitterness."


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## welly2 (21/5/16)

That was bitterness in the title.


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## Yob (21/5/16)

Written vy whom based on what?


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## Ducatiboy stu (21/5/16)

welly2 said:


> "One thing I see a lot of with bad homebrew IPA is that guys will cold crash their carboys to get the hops to fall to the bottom before bottling/kegging. This will cause oxidation that can be perceived as excessive bitterness."


I call bullshit on that one.

Cold crashing wont affect oxidation


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## Zorco (21/5/16)

https://www.reddit.com/r/Homebrewing/comments/23h4ap/aftertaste_on_my_ipa_has_a_harsh_bitterness/


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## Zorco (21/5/16)

I'm still going through the autopsy of my failed 40 litres of APA where my fridge chilled, warmed, chilled, warmed a few times. The change in air density would have effectively created a pump that would have caused air to come into the fermenter on the cool cycle and whatever CO2/air blend to be expelled on the warm cycle. Several cycles may have diluted my CO2 blanket and possibly the air inrush caused acetobacter to be given tickets to my ethanol.

I don't know if/how CO2 homogenises with air or if CO2 just blankets the beer still.

Only a hypothesis at this stage, but potentially a cause for O2 ingress into a fermenter upon cold crashing (of course depending on wort volume in the vessel, gas headspace and vessel geometry)


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## Zorco (24/5/16)

I wanted to bump this one. 

Any substance to this approach to the situation? 

Welly, are you your hops fresh, aged, frozen?


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## Patrick_BCB (25/5/16)

From the very few brews I have done I noticed an increase in bitterness when doing no-chill and not adjusting my in kettle hop addition schedule.


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## indica86 (25/5/16)

hat is a load of shit.
welly, post a recipe and method, that may help.


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## wynnum1 (25/5/16)

Could it be the water.


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## manticle (25/5/16)

As much as I like the word vitrernest, I've edited the title for you.


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## wynnum1 (25/5/16)

manticle said:


> As much as I like the word vitrernest, I've edited the title for you.


If you want to spell check use google.
Except if you have already used the word .

vitrernest
http://aussiehomebrewer.com/topic/91017-harsh-hop-bitterness/


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## TheWiggman (25/5/16)

I'm not a gun taster but I don't think I've ever mixed up oxidation with bitterness. Even what you're saying cosdog is a bit of a stretch (not having a go), because racking to a secondary is a common enough practice and there is a huge increase in oxygen exposure in doing so than leaving the beer in the primary. I've done it before and when done properly i.e. minimal disturbing, cold temps, hit of CO2 prior there is negligible impact on the flavour/longevity. Minimal sucking in from chilling... can't see it making a poofteenth of difference.
I feel like commenting on this is like commenting on a sensationalist headline and I feel guilty that I've been trolled.


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## Matplat (25/5/16)

Even if you draw air in while cold crashing, CO2 is heavier than air so the CO2 blanket will still protect the beer....


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## sp0rk (25/5/16)

welly2 said:


> Trying to get to the bottom of a bitterness issue I've been noticing in my beers. Read this on reddit and wondered if there's any truth to it:
> 
> "One thing I see a lot of with bad homebrew IPA is that guys will cold crash their carboys to get the hops to fall to the bottom before bottling/kegging. This will cause oxidation that can be perceived as excessive bitterness."


The bloke who wrote this claims he's been brewing professionally and at home for a decade
But his comments on Reddit make me question some of his advice...


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## rude (25/5/16)

wynnum1 said:


> Could it be the water.


Im going with water as well but I have been going water mad lately


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## Zorco (25/5/16)

TheWiggman said:


> I'm not a gun taster but I don't think I've ever mixed up oxidation with bitterness. Even what you're saying cosdog is a bit of a stretch (not having a go), because racking to a secondary is a common enough practice and there is a huge increase in oxygen exposure in doing so than leaving the beer in the primary. I've done it before and when done properly i.e. minimal disturbing, cold temps, hit of CO2 prior there is negligible impact on the flavour/longevity. Minimal sucking in from chilling... can't see it making a poofteenth of difference.
> I feel like commenting on this is like commenting on a sensationalist headline and I feel guilty that I've been trolled.


It is a stretch..... I'm fishing. I think the cold crash cycling might have helped grubs get in. I'm not convinced it is a process that supports any meaningful oxidation for the OP.

Totally enjoy being told I'm wrong or off target - I'm a curious and life long learner.


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## TheWiggman (25/5/16)

sp0rk said:


> The bloke who wrote this claims he's been brewing professionally and at home for a decade
> But his comments on Reddit make me question some of his advice...


The wonder of the internet. I'm actually an astronaut with 20 years' experience, been to space only 6 times but still know my stuff.


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## welly2 (25/5/16)

indica86 said:


> hat is a load of shit.
> welly, post a recipe and method, that may help.


The beer in particular I was thinking about was a pretty simple pale ale. Hops were relatively new (frozen since I bought them a few months ago). Nothing too clever.


4.20 kg

Pale Malt, Traditional Ale (Joe White) (5.9 EBC)

Grain

1

350.0 g

Caramalt (Joe White) (49.2 EBC)

Grain

2

200.0 g

Crystal, Light (Simpsons) (80.0 EBC)

Grain

3

200.0 g

Munich Malt (17.7 EBC)

Grain

4

13.0 g

Columbus (Tomahawk) [14.0%] - Boil 75 min

Hops

5

15.0 g

Amarillo Gold [8.5%] - Boil 30 min

Hops

6

15.0 g

Columbus (Tomahawk) [14.0%] - Boil 30 min

Hops

7

1.32

Whirlfloc Tablet (Boil 15 min)

Misc

8

15.0 g

Amarillo Gold [8.5%] - Boil 0 min

Hops

9

15.0 g

Columbus (Tomahawk) [14.0%] - Boil 0 min

Hops

10

1 pkgs

US-05

Yeast

11

1.32 tsp

Yeast Nutrient

Misc

12

50.0 g

Cascade [5.5%] - Dry Hop 3 days

Hops

13









Maybe it was just me as everyone else seemed to enjoy it and drink it.


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## Danscraftbeer (25/5/16)

> It is a stretch..... I'm fishing. I think the cold crash cycling might have helped grubs get in. I'm not convinced it is a process that supports any meaningful oxidation for the OP.
> 
> Totally enjoy being told I'm wrong or off target - I'm a curious and life long learner.


If cold crashing my opinion is that it should be air tight so it doesn't draw in any air.
That also means the walls of a plastic fermenter will cave in when it contracts.
Added 2c I made Stainless Steal plugs that fit tight in the airlock grommet. 30mm long 10mm thick stainless round rod rounded off one end and polished. Oh the things we do....


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## Diesel80 (25/5/16)

Welly, if it is too bitter cold. Warm it up, takes the edge off somewhat.

Cheers,
D80


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## manticle (25/5/16)

Have you used those hops in a similar way before?


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## danestead (25/5/16)

Is it astringency you are getting? I was getting astringency in pretty much all of my brews. I was screwing around with water too much and since backing right off on the water side of things, my brews have improved immensely. There was a batch of IIPA I brewed recently, which was very astringent post dry hopping, that I tipped. I dry hopped it after it had reached FG and after it was taken off the yeast. My current thoughts are that because the yeast had already finished it's job, the harsh astringency of raw hops (try eat some one day, you'll know what I mean) was carried over into the beer. My thinking is that the magic of yeast , whilst active, does wonderful things to astringency, and that dry hopping should occur just prior to FG to let that magic take place. I do want to have a chat with some pro brewers to see if my theory is correct though - and see how they do it.


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## Zorco (25/5/16)

Danscraftbeer said:


> If cold crashing my opinion is that it should be air tight so it doesn't draw in any air.
> That also means the walls of a plastic fermenter will cave in when it contracts.
> Added 2c I made Stainless Steal plugs that fit tight in the airlock grommet. 30mm long 10mm thick stainless round rod rounded off one end and polished. Oh the things we do....


Top idea,

I misplaced one of my thermowells and plugged the second grommet with a 12mm barb with a stainless cap on the end. Not as elegant due to all the angles and threads.

I wish I had a lathe. Men have lathes.


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## TheWiggman (25/5/16)

Actually fair point by manticle, welly commented that he's having bitterness issues with his beers. Maybe this is what we should be discussing rather than a highly questionable web post?
What's your process welly2, are there specific beers you are getting the issue with?


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## Zorco (25/5/16)

There have been a couple of pointers to the water. How could this influence bitterness?


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## Frothy1 (25/5/16)

zorsoc_cosdog said:


> There have been a couple of pointers to the water. How could this influence bitterness?



Chloride / Sulfate ratio.

Too much sulfate may enhances bitterness.


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## danestead (25/5/16)

zorsoc_cosdog said:


> There have been a couple of pointers to the water. How could this influence bitterness?


I was using RO/DI water, then adding various combinations of salts to end up with a predetermined water profile. The salts I was using were some, or all of the following: Calcium Chloride and Sulphate, Magnesium Sulphate, Chalk and Bicarbonate of Soda. When changing to RO (not RO/DI) water, mixed with various percentages of Perth tap water, my astringency (as opposed to bitterness) issues largely disappeared. Why? I don't know for sure; however the positive change has been noted by myself, and others.


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## rude (25/5/16)

I was using Melville water high in sodium ,chloride I backed right off on the hops
because of the bitterness harshness
A English bitter I was going from 32 IBU to 25

Since R,O water use beers have been coming out malty can actually taste the yeasts flavours,
have had to readjust hop schedule where Im thinking maybe a touch more than 32 IBUs

It may have been astringency from high PH ? but it has made a big difference
Also not as dry after a session
Before I'de wake up dry as a Nuns nasty

Note I'm a no chiller & have been just hopping in the kettle lately but have cubed hopped before


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## Danscraftbeer (25/5/16)

How one questionable harsh flavour turns into a can of worms. :lol:

Notes, notes, take notes etc, more notes, and take more notes and judge of your own beers.

My beers are more malty these days but with a bitter enough backbone to them as well. On tap 20 days from grain to brain. 
I need more kegs for longer conditioning.


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## manticle (25/5/16)

zorsoc_cosdog said:


> I wish I had a lathe. Men have lathes.


Soon I hope to buy a lathe for my workplace so I can make sexy things from aluminium and stainless.


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## quadbox (25/5/16)

I was looking for molar solubility graphs, but close enough for internet handwaving points regardless. The solubility of oxygen at 0C (crash chilling temps) is still utterly miserable compared to co2. Will 0.07grams of oxygen per kilogram of beer oxidise more than 0.04 grams? Hell yes. Will that be measurable compared to other factors involved at the early stages of conditioning? Lol.

The entire "CO2 blanket protects your beer" thing has been debunked very thoroughly, very often, but wow does it forever rise from the grave.


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## manticle (25/5/16)

I sleep with a co2 blanket.


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## Danscraftbeer (25/5/16)

That graph reassures my suspicions. I'll advocate for no exposures of your beer is best. I'll go the hop stands instead of throwing dry pellets or flowers into a post ferment beer.


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## Matplat (25/5/16)

Please elaborate.... I haven't heard of this debunking previously? 

Seems plausible enough to me that in the same way salad dressing separates in the jar, an undisturbed atmosphere in the top of your FV will do the same thing with CO2 and any remaining air? 

Isn't that what allows open top fermentation vessels to work?


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## manticle (25/5/16)

My understanding is that co2 offers protection while it's being produced during fermentation (some - it's not a mylar or cryovac barrier). However once fermentation slows or stops, your blanket gets thinner every second.

Some brewers seem to think they could have house guests sleep under it for half a year.


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## Danscraftbeer (25/5/16)

Yeah. Then when your beer cools it absorbs that Co2 layer. Then it probably absorbs your used fridge air if its not air tight.

Edit: my notes; A standard 30lt plastic fermenter with a 20lt brew. Cold chilling will draw in a basket ball worth of volume of air. 
Cant rely on a Co2 layer there.


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## mckenry (25/5/16)

Put simply if CO2 and air didn't mix, we'd all be dead. The 'protective layer' would be on earth and the air would be above that.


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## GalBrew (25/5/16)

You need to keep in mind gas partial pressures when the magical co2 blanket is discussed.


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## Zorco (25/5/16)

mckenry said:


> Put simply if CO2 and air didn't mix, we'd all be dead. The 'protective layer' would be on earth and the air would be above that.


I thought about this but realised that the sun's energy leads to atmospheric turbulence and therefore mixing of the gases.

Not the same for the fermenter. There must be a property of dissimilar gases to homogenise. Is it just entropy? Is the rate of diffusion less than the natural mixing due to the high temperature (yes, I mean 0C) of the gases?


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## MastersBrewery (25/5/16)

manticle said:


> I sleep with a co2 blanket.


I would but SWMBO gets a lil jealous.

I have really only noticed harshness from an APA when ferm temps went nuts on me.(when I first move I wasn't setup but was hangin for a brew. I should have waited it ended up on the lawn) Or when underpitched, yeah I have thrown handfuls of hops at brews but I find time has always allowed them to settle and mellow some.


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## Frothy1 (25/5/16)

Danscraftbeer said:


> Yeah. Then when your beer cools it absorbs that Co2 layer. Then it probably absorbs your used fridge air if its not air tight.
> 
> Edit: my notes; A standard 30lt plastic fermenter with a 20lt brew. Cold chilling will draw in a basket ball worth of volume of air.
> Cant rely on a Co2 layer there.


Are we way OT?


When I move the FV from the fridge to the bench to keg, i see air lock activity (air going into the vat) in the small amount of time to get my shit together, maybe a minute or so.

I have never seen air lock activity when cold crashing, yes I'm always looking in the fridge.


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## TheWiggman (26/5/16)

Danscraftbeer said:


> Yeah. Then when your beer cools it absorbs that Co2 layer. Then it probably absorbs your used fridge air if its not air tight.
> 
> Edit: my notes; A standard 30lt plastic fermenter with a 20lt brew. *Cold chilling will draw in a basket ball worth of volume of air. *
> Cant rely on a Co2 layer there.


I'm not sure if you've made a typo but that's not even close. The difference is about 7% from 18°C to freezing. For 10l of dead space, that's 70ml of air drawn in which is 20% oxygen. Thus half a shot of oxygen will enter the space which will make stuff al difference if the liquid is kept cool and not agitated for a short period of time. I'd love to see some knowledgeable evidence behind the gas layers concept because I'm not convinced the different constituents simply separate themselves out in a still environment.

I've buggered up beer with poor yeast management, temps, infections, bad malt choices, too much hops, hop addition timing, storage, cleanliness and many other ways but I've yet to over-oxidise a beer by crash chilling it (and 100% confident I never will).


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## Coodgee (26/5/16)

TheWiggman said:


> I'm not sure if you've made a typo but that's not even close. The difference is about 7% from 18°C to freezing. For 10l of dead space, that's 70ml of air drawn in which is 20% oxygen. Thus half a shot of oxygen will enter the space which will make stuff al difference if the liquid is kept cool and not agitated for a short period of time. I'd love to see some knowledgeable evidence behind the gas layers concept because I'm not convinced the different constituents simply separate themselves out in a still environment.
> 
> I've buggered up beer with poor yeast management, temps, infections, bad malt choices, too much hops, hop addition timing, storage, cleanliness and many other ways but I've yet to over-oxidise a beer by crash chilling it (and 100% confident I never will).


completely agree with the sentiments here but 10L of deadspace would be 10,000ml, 7% of which would be 700ml - so 5 shots of oxygen.


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## MHB (26/5/16)

CO2 is used in fire extinguishers as it will displace O2, you can suffocate in a high CO2 environment...
When there is plenty of CO2 it will temporally displace all the other atmosphere, this includes on top of the beer in a fermenter, in the fridge; I think it gives good O2 protection while there is plenty being evolved.
It doesn't last, it slowly dissipates and blends into the air, then you have no protection at all.

if a 1.050 beer fermented to 1.010 40 points of gravity apparent attenuation or 10oP, 8.2oP real attenuation.
in a 23L ferment 1.886kg of sugars fermented gives 883g of CO2 MW is about 44g/M call it 20 moles at 22.4L/M , just under 450L of CO2
So we are talking fairly significant amounts being evolved during a brew.
Mark


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## MastersBrewery (26/5/16)

MHB said:


> CO2 is used in fire extinguishers as it will displace O2, you can suffocate in a high CO2 environment...
> When there is plenty of CO2 it will temporally displace all the other atmosphere, this includes on top of the beer in a fermenter, in the fridge; I think it gives good O2 protection while there is plenty being evolved.
> It doesn't last, it slowly dissipates and blends into the air, then you have no protection at all.
> 
> ...


So as most of the ferment is done in the first 3 days, in the example above your brew is outputing 5L an hour on average.


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## Zorco (26/5/16)

Brownish Motion. This seems to be appropriate to my last post

(Wish I didn't just focus on electrical)

http://www.physbot.co.uk/gas-laws.html

As MHB points out, the CO2 protection is best while it is continuously being evolved.

Cold crashing will increase the density of the CO2 and to equalise pressure, air ingress will occur ( through the airlock).

The gases will mix, through a combination of the turbulence of the air pulsing through the airlock as well as the natural motion of the particles.

From the posts above, that amount (20% O2) will not oxidase to any significant degree.

Back to my failed batch, it was almost an open ferment by using a pot. There was no sanitiser to prevent the ingress of acetobacter. And entropy would have mixed the air and acetobacter will have accessed my beer.

Any corrective additions?

Edit: stated as my first conclusion, not as an authority.


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## GalBrew (26/5/16)

The gases will mix due to their partial pressures.


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## Danscraftbeer (26/5/16)

TheWiggman said:


> I'm not sure if you've made a typo but that's not even close. The difference is about 7% from 18°C to freezing. For 10l of dead space, that's 70ml of air drawn in which is 20% oxygen. Thus half a shot of oxygen will enter the space which will make stuff al difference if the liquid is kept cool and not agitated for a short period of time. I'd love to see some knowledgeable evidence behind the gas layers concept because I'm not convinced the different constituents simply separate themselves out in a still environment.
> 
> I've buggered up beer with poor yeast management, temps, infections, bad malt choices, too much hops, hop addition timing, storage, cleanliness and many other ways but I've yet to over-oxidise a beer by crash chilling it (and 100% confident I never will).


I made the basket ball volume reference simple by seeing just how much the walls of a 30lt plastic fermenter will contract when its air tight from 18c to say 2c. I say for anyone to try it and see just how much it contracts. Its about the volume of a basketball. I wish I took a photo for reference now. Far from an expert and bordering on paranoia of contaminating beer but the way I see it if the fermenter is not air tight then that volume will be replaced by fridge air.
Anyhow Its enough to influence me into a kegmenter and co2 transfers etc. I don't have to worry about any of this anymore. B)


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## GalBrew (26/5/16)

Danscraftbeer said:


> I made the basket ball volume reference simple by seeing just how much the walls of a 30lt plastic fermenter will contract when its air tight from 18c to say 2c. I say for anyone to try it and see just how much it contracts. Its about the volume of a basketball. I wish I took a photo for reference now. Far from an expert and bordering on paranoia of contaminating beer but the way I see it if the fermenter is not air tight then that volume will be replaced by fridge air.
> Anyhow Its enough to influence me into a kegmenter and co2 transfers etc. I don't have to worry about any of this anymore. B)


I use a sterilock for cold crashing, so contamination isn't an issue. I've not noticed any oxidation in my beers early on from the air introduced into the fermenter during cold crashing (doesn't mean it doesn't happen though).


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## rockeye84 (26/5/16)

Been down this road. My bet would be on boil ph. You could try bumping your hop utilisation in your brew software up 10% as well, I run my hop utilisation in beer smith 2 @ 120%.


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