Why do hop flavours fade?

[ChristinaS1]

Why do hop flavours fade? I think we all all familiar with late and dry hop flavour (essential oils) fading fast. But even early kettle additions/bitterness (alpha acids) fade over time. Is it physics, or the action of yeast?

 

Does filtering out the yeast preserve essential oils, to a point anyway?

 

Does cold storage preserve either essential oils or iso-alpha acids?

 

Cheers,

 

Christina.

[Hermoor]

Here is an article that I read that gave me a basic understanding on what goes on in the bottle

 

http://hookedonhops.com/2014/01/20/an-updated-guide-to-aging-beers/

 

 

[ChristinaS1]

Just reading that one source of loss of myrcene, caryophyllene, and humulene is migration to the PVC liners of crown caps and lids, a process called scalping.

 

Oxidation/acid hydrolysis reactions also lead to the conversion of aroma compounds to other compounds,

 

https://beersensoryscience.wordpress.com/category/aroma-2/

 

And flip-top lids (which I use) are bad for letting aroma escape. Yikes!

 

Cheers,

 

Christina.

[joolbag]

Hey Christina I also use Grolsch swing-tops as well as crown seal caps. I will pay closer attention if hop aroma is greater in the crown seal bottles than my swing tops. I have'nt noticed it yet, but I do drink my hoppy beers young.

 

I have read about oxygen barrier/scavenging crown seal caps being used to preserve beer and the hop freshness. I might investigate this myself in the future.

[ChristinaS1]

Hi Joolbag. I am going to do a little experiment. I bought eight brown, pry off glass bottles and next time I bottle I am going to fill them. I will save them until I begin to notice hop flavours in my Grolsch bottles starting to fade, and then do a side-by-side comparison a couple of times a week, to see if there is any difference. I will report back.

 

I want to save the slurry from this batch so, in addition to the above little experiment, I am also going to try making a hop tea and adding it to my bottling bucket, instead of dry hopping. I haven't actually ever done this, in spite of it making a lot of sense to me.

 

I am planning to steep the hops in 75C water (sub-isomerization temperature) for 20 minutes.

 

Cheers,

 

Christina.

[BlackSands]

I am planning to steep the hops in 75C water (sub-isomerization temperature) for 20 minutes.

Just curious - in the hop stand duration thread you said:

 

...the experiment really showed the benefit of doing hop stands' date=' with [b']10 minutes[/b] looking like the best length of time, which agrees with alchemyoverlord's results.

 

[ChristinaS1]

I am planning to steep the hops in 75C water (sub-isomerization temperature) for 20 minutes.

Just curious - in the hop stand duration thread you said:

 

...the experiment really showed the benefit of doing hop stands' date=' with [b']10 minutes[/b] looking like the best length of time, which agrees with alchemyoverlord's results.

 

 

Yes, but that is starting with hops added at FO and allowed to cool passively = hotter temperatures.

 

This time around I will follow Gerard Lemmens' process, the guy who invented (or at least popularized) adding hop teas at bottling time.

 

I should probably do a side-by-side, but I don't want to put the effort in. I might try using water just off the boil with a 10 minute steep next time (pre-bottling).

 

Cheers,

 

Christina.

[ChristinaS1]

Here is an interesting German study done regarding the fate of dry hop substances after packaging in crown cap bottles at 20C for 100 days.

 

http://www.agraria.com.br/extranet/arquivos/agromalte_arquivo/fatos_substancias_dry_hopping_brewingscience_-_ing.pdf

 

The study had an interesting way of dosing the dry hops, using % oil content instead of weight, to even out the comparisons between the four different hop varieties they used.

 

Myrecene dropped by 75%, humulene and caryophellene by ~50%, due to absorption in cap liners, but what surprising is that geraniol actually increased by 92%, and linolool by 21%. That caught me by surprise.

 

Cheers,

 

Christina

[Beerlust]

The study had an interesting way of dosing the dry hops' date=' using % oil content instead of weight, to even out the comparisons between the four different hop varieties they used.[/quote']

As an isolation experiment, I think it has some merit, but oils ain't oils.

Myrecene dropped by 75%' date=' humulene and caryophellene by ~50%, due to absorption in cap liners, but what surprising is that geraniol actually increased by 92%, and linolool by 21%. That caught me by surprise.[/quote']

I don't know that they increase per say, but geraniol & linalool certainly become more noticeable for a period of time as other more potent aspects drop off. The percentage of geraniol & linalool in most hops is around 0.5% whereas myrcene in very aromatic & flavoursome hops is around 35%+.

 

Beerandbrewing Magazine.com - Don't Age These Beers

 

Myrcene appears to be the most notable component that affects aroma per ml of hop oil when dry hopping from what I've read. In hops that have notable aroma/flavour forward attributes the levels of myrcene appear to be higher than that of hops that are not particularly aromatic. The level of geraniol & linalool appear (to me at least) to be incidental as a direct link as to whether a hop will provide enduring flavour/aroma.

 

With all the studies & so-called facts out there on the WWW, often the numbers & advice sound very cool & convincing. Take on board what you think might be beneficial, but then in a practical brewing sense, test it for it's validity. There's a lot posted out there that is bullshit, maybe even some of mine.

 

Cheers,

 

Lusty.

[ChristinaS1]

Question about cold crashing: air gets sucked back through the airlock when cold crashing. Presumably some of the oxygen sucked back ends up in the beer.

 

If oxygen leads to oxidation / staling of beer and hops, does cold crashing promote the degradation of dry hop aroma and flavour compounds, in other words, does it accelerate their loss?

 

In the case of bottle conditioned beers, will there be enough secondary fermentation in the bottle (yeast activity) to mop up that oxygen?

 

Cheers,

 

Christina.

[Otto Von Blotto]

I don't think enough of that oxygen ends up in the beer during a cold crash to present any issues, sure the pressure drops but there's still nothing really forcing the oxygen into the beer. It should also be noted that even without a cold crash, oxygen will still get in after fermentation is finished simply because there's nothing pushing it out anymore. In that sense, the magical CO2 blanket is a myth. It's only a temporary existence during the active fermentation phase, after that's over there's nothing to stop other gases from getting in and mixing with it again.

 

I've been cold crashing for years and haven't had any oxidised beers from it or beers losing hop presence, bottled or kegged. Sure, it drops a little over time but those hoppy beers are never aged so it doesn't really matter anyway. Pale ales I usually keg and put straight on gas then tap them a couple of days later. When I was bottling I'd start drinking them after a couple of weeks in the bottle and they never lasted much past the 6 week mark.

 

It's still an interesting subject, but I think the best thing to do is simply work out which styles are best drunk early and which ones are better to be aged for a period of time first; to me the hoppy ones are the ones you don't really want to age, while the darker, maltier brews benefit from it.

[headmaster]

Very interesting to read this!

 

I've just documented what I believe to be a massive difference in hop aroma in my IPA that I submitted to the latest ISB competition in Sydney.

 

I was a steward at this comp, and actually sat with the judges as they judged my beer. Mysterious low aroma, got marked down for that but still took out third place.

 

The judges were amazed when after they found out it was my beer (only after finishing the judging) that I had used some 120g of cascade simcoe and centennial for the dry hops.

 

It was only 3 weeks in the bottle as well.

 

I had submitted the beer bottled in a 750ml PET for safety reasons really. I tasted it and yes almost no aroma. All the rest I had bottled in glass.

 

Drinking the ones from glass at home however, they still have a big whack of aroma. so I suspect the PET has something to do with this?

 

If so there's a big lesson in this for me.

[ChristinaS1]

Very interesting to read this!

 

I've just documented what I believe to be a massive difference in hop aroma in my IPA that I submitted to the latest ISB competition in Sydney.

 

I was a steward at this comp' date=' and actually sat with the judges as they judged my beer. Mysterious low aroma, got marked down for that but still took out third place.

 

The judges were amazed when after they found out it was my beer (only after finishing the judging) that I had used some 120g of cascade simcoe and centennial for the dry hops.

 

It was only 3 weeks in the bottle as well.

 

I submitted my only one bottled in PET for safety reasons really. I tasted it and yes almost no aroma.

 

Drinking the ones from glass at home however, they still have a big whack of aroma. so I suspect the PET has something to do with this?

 

If so there's a bit lesson in this for me. [/quote']

 

Thanks for sharing that experience Headmaster. I think you are right about the PET bottles being to blame. They are not air tight. They are probably the worst type of packaging for a home brewer to use. No good for hoppy brews or for aging stouts.

 

It seems some big American craft breweries are taking a page out of German Helles brewers handbook and are trying to keep oxygen levels as low as possible throughout the entire brewing process, even on the hot side. Opinions in the USA are split as to whether one needs to minimize hot side aeration, with most saying it isn't necessary, but pretty well everyone accepts that keeping oxygen out of beer post fermentation is very important.

 

Years ago I noticed already that brews fermented in my glass carboy tasted fresher than those fermented in my plastic bucket, or my PET carboy, and it is probably for the same reason. Brulosophy has done a couple of experiments that concur with my observations. He found that PET carboys produce different results than plastic buckets, and that 10 of 12 blind tasters (who were able to tell them apart) preferred the beer fermented in a glass carboy to the same beer fermented a PET carboy. These tests both had statistically significant results.

 

http://brulosophy.com/2014/10/14/the-impact-of-fermentation-vessel-exbeeriment-results/

 

http://brulosophy.com/2016/05/16/fermentor-type-pt-2-plastic-pet-vs-glass-carboy-exbeeriment-results/

 

If I was making beer for competition, I would ferment in a glass carboy with an airlock. I would definitely avoid using a FV designed to be used without an airlock, such as the Coopers FV, nor would I use cling wrap. I know some on the forum think airlocks are crap and should be thrown away, but once fermentation has died down it is important to keep oxygen out of the FV. The easiest way for a home brewer to guard against it is to use a glass carboy and an airlock.

 

I bulk prime and use an auto-siphon to rack and bottle; there are always bubbles in the tubing. I regret them but on the other hand there is not much I can do about it. I just hope yeast activity during bottle conditioning will clean it up.

 

I sometimes wonder if bottling from a primary with a tap, using carbonation drops, would be better, but at this point I am not planning to change my equipment or process....There is no such thing as a glass carboy with a tap; that would probably be ideal, although taps are infection risks.

 

Cheers,

 

Christina.

[Otto Von Blotto]

Rather than a glass carboy you could use a stainless steel fermenter (like the commercials use) which is able to have a tap fitted to it. Safer than glass too. I was thinking about getting one of those olive oil drums to use as a fermenter but I'm just not sure if it would fit in my brew fridge.

 

If I could I'd get one of these, but I know for sure that it would be too tall for my fridge. Probably the best fermenter on the market however.

 

[Wobbly74]

Another option is a stainless kegmenter. KK sell a large one, I bought a 26L one from ibrew for easier fridge figment. Not sure when they're back in stock.

 

https://www.ibrew.com.au/products/kegmenter-20-and-26-litre-from

 

Let's you do pressure transfers to kegs or bottles to avoid any additional o2 exposure when packaging.

[headmaster]

I haven’t had issues with oxidation using the Coopers FV’s, apart from one beer, an APA that I also submitted to a comp, the 2017 NSW State comp from memory, that was noted as being slightly oxidised and when I thought about the taste, it was a bit.

 

Looking back at my notes for this APA, what I did differently to almost all other beers, was that I racked secondary, in another coopers FV. At the time I thought that doing so may leave it without the protective blanket of CO2 that ’should’ exist in primary, (if not disturbed too much)

 

I hoped that CO2 breathing out of the beer during secondary would sort this out. It was in secondary only 5 days, one day at 18c, 4 days cold crashing, then racked again onto priming sugar in bottling vessel (also another FV)

 

So it seems from this, I should use a different vessel if I ever need to rack to secondary, that has a much lower headspace, or be able to purge the O2 with CO2 maybe.

 

I don’t think I would need glass carboys unless I wanted to store in secondary for a long time, for eg if I got into making meads, or sours. (Oxygen + sours can = baby chuck off flavours…)

 

I guess/hope the O2 that is introduced with my usual process is consumed in bottle conditioning.

 

Have submitted possibly over 25 beers to competitions since my first one in late 2016, only that one described above got a mention of oxidation.

 

In the most recent comp (ISB Club Comp) where my IPA was lacking aroma, I also submitted a Weissbier that was in PET that had been in the bottle for three months (but in the fridge) it received the highest score for a Weissbier, also a Kolsch which also received the highest for a kolsch, that one was in glass, but both using Coopers FV’s and racked for bulk priming, (so bottle conditioned) no mention of oxidation in scoresheets.

 

The going joke at the comp was my bottle of Saison, which if you look at the scoresheets got the first zero in the history of the comp, as the PET bottle I submitted developed a fissure in the bottom (the stands at the bottom, weak points) and leaked out under 3.3 vols of pressure. There was a couple of teaspoons of beer left in the bottom of that bottle! A bit disappointed as that was my very first Saison and I was quite proud of the way it tasted. My takeaway from all of this is I will never be using PET for a comp in the future.

 

I will however look into obtaining a tirage bell for my bench capper and start collecting some champers bottles.

 

Placegetters here for the ISB Comp

 

 

[ChristinaS1]

What is a triage bell?

[joolbag]

Sorry to hear about the saison in the comp headmaster!

 

Interesting points there about your IPA and lack of aroma in the competition sample. I think the risk of exploding bottles is low for your regular beers carbonated to 2.5vols CO2. Especially as we don't rush and make sure the fermentation is well and truly finished before packaging.

 

I haven't ever used PETs and given your experience (and Blacksands, and KR) I am glad I went straight to glass bottles!

 

Qn: how firmly do you cap your bottles using the bench capper? I don't put that much pressure on and you have me thinking that I should be really jamming down these crown caps. Oxygen scavenging caps are also an area of interest to me too. Perhaps next time there is a bulk buy on AHB.

 

Cheers

 

Jools

[Otto Von Blotto]

I used to use a large drill press as a "bench capper", which probably provided more force to crimp the crown seals over the bottle tops, but didn't require much on my part to do it. Not really a comparison to a bench capper, however I'd suggest you only need as much force as is required to properly crimp the crown seal over the bottle. If they are loose enough to allow oxygen ingress then the beer won't carbonate in the first place as CO2 can also escape.

[headmaster]

What is a triage bell?

 

A Tirage bell is simply a crown seal bell designed for the slightly larger 29mm crown seals that can be used on a standard champagne bottle. I think the crown lip is there as part of the methode champenoise for temp sealing before final cork and cage put on after yeast expelled.

 

I just bought one online and 100 tirage seals, usually twice or up to 4 times more expensive as normal crown seals.

 

A Triage bell may be used in a hospital :-)

[headmaster]

 

I think the risk of exploding bottles is low for your regular beers carbonated to 2.5vols CO2. Especially as we don't rush and make sure the fermentation is well and truly finished before packaging.

I do tend to agree there' date=' I should be fine. Part of it was, I was pushing the limits with the saison, very high carb at 3.3V

 

Qn: how firmly do you cap your bottles using the bench capper?

 

I have a very old 'Geartop' that was my grandfathers, rack and pinion thing, maybe 90 odd years old, still works great :-) I give the seals enough force to leave no doubt about the seal. I would be very surprised if anything gets out, I think the hop aromas are not leaving out with these, the research shows they are actually being absorbed into the PVC sealing material.

 

Oxygen scavenging caps are also an area of interest to me too. Perhaps next time there is a bulk buy on AHB.

 

I am interested in these if the sealing material is also less likely to absorb hop aromas!

 

I will still continue bottling one PET per batch as very good for carbonation level 'Squeeze test'

[ChristinaS1]

I just listened to an episode of Brew Basic radio, and interview with John Palmer on NEIPAs, taped in February, and they specifically discussed preserving hop flavour and aroma starting at minute 47:

 

http://hwcdn.libsyn.com/p/8/f/5/8f58e82370bb3396/bbr02-01-18neipapalmer.mp3?c_id=18891350&expiration=1522331678&hwt=3f24ea62b0cd7af5bef16dbb2e0dd2ba

 

Palmer confirmed, as we have already discussed, that the reason hop flavours and aroma fade is oxidation. He recommended purging head space in kegs and chilling, which would have to wait until after carbonation in the case of bottles. He really stressed chilling, calling it "critical."

 

Cheers,

 

Christina.

 

 

[Otto Von Blotto]

I always purge my kegs after filling them but unfortunately have no way of keeping them chilled, except when it's a batch that goes straight into the kegerator after being kegged. I'm just patiently waiting for the missus to decide to upgrade the kitchen fridge so I can steal it for storing kegs

[ChristinaS1]

I always purge my kegs after filling them but unfortunately have no way of keeping them chilled' date=' except when it's a batch that goes straight into the kegerator after being kegged. I'm just patiently waiting for the missus to decide to upgrade the kitchen fridge so I can steal it for storing kegs [img']lol[/img]

 

Yeah, a fridge would be great. Knowing you, you'll get one eventually, one way or another. Meanwhile, with a little bit of planning, you could probably make a NEIPA / hoppy beer and get into your kegerator straight away, or almost straight away.

 

Wish we had room for a fridge because the more I read about the NEIPA style, the more I think I'd really like it. I am working on a recipe, which will be my first partial mash + extract brew without using a pre-hopped kit as the base....It is disappointing to know ahead of time that because I don't keg, and can't keep my bottles cold after carbonation, the initial flavour and aroma won't last until I reach the end of the batch....For some reason, the style seems particularly prone to oxidation. Probably the best I can do is bottle a little earlier than I usually do, to buy some time on the front end.

 

I know you no chill. Just out of curiosity, how long do you leave them before adding the yeast, when you make a hoppy recipe? Or do you stick more to Pils?

 

Cheers Kelsey,

 

Christina.

[Otto Von Blotto]

Yeah, I used to brew in blocks of 3 batches at a time because I have 3 taps, lagers first, something else second and pale ales were always the last of the 3 to be brewed so they could go in as soon as possible after being kegged, but I've since dropped down to using two beer taps and the other one permanently on soda water for cordials and such, which has for some reason made it easier to keep up beer production with consumption so I'm not having to buy beer much at all now. Before I'd run out and have to wait up to a month for the third keg to be ready before I'd tap all three. I still brew in the same order but the pale ales don't always get on tap straight away or close to it anymore. Hasn't seemed to have affected them too much though.

 

I don't brew every weekend, mainly I just brew when I need a batch; for the last few months pretty well every batch has been brewed only a few days before the yeast has been pitched, occasionally they might sit there for a couple of weeks but hardly ever are they sitting there for a month or longer anymore. I hadn't noticed any difference between cubes stored longer or shorter in terms of hop flavor though.

 

I brew more ales than lagers, usually two ales for every one lager and they vary between pale ales, ESBs, my red ale and the darker ales, occasionally I'll do an IPA but not often.

 

Cheers

 

Kelsey