Preserving hopiness.

[bum]

No way, man.

 

[MaltyHops]

"our water tank which sits around 22-24 deg"

Yeah, I can see how this would work.

But that's more like 80-84 degree :lol:

 

[Bizier]

Hop flavour was once there but has faded so chilling method should be irrelevant.

With respect, I disagree. There is a thing called thermal degradation units in pasteurisation, which is a measure of elevated temperatures that are not just over 60ºC. High TDUs indicates shortened shelf life. Hop profiles are basically the first to go.

I think you should try a cf chiller and purge everything with CO2.

 

[manticle]

Interested. Tell me more (or tell me where I can find out more)

 

[Bizier]

It is integral to any beer pasteurisation educational literature.

http://www.redpostltd.com/support/science#TDU
From a popular PU measurement instrument manufacturer.

 

[manticle]

Cheers.

So if I interpret what you are saying correctly, you are suggesting that the extra time an NC brew spends hot will encourage degradation of flavour in the same way a brew stored warm will accelerate staling reactions (from pathways already begun during the malting and mashing processes).

Just as too hot for too long during pasteurisation post fermentation (ironically designed to help stabilise for long term) will degrade flavour so can too hot for too long during cooling (pre-fermentation)?

 

[Bizier]

Oxidising reactions are accelerated at hotter temps. I know it is not apples and apples because there are many chemical changes in fermentation, but in the interests of Dave retaining a delicate hop profile it is my suggestion to limit thermal degradation post-boil.

Basically all pasteurisation literature I've read uses 'delicate beers' like pilsner as an example where pasteurisation control is critical and where minimum pasteurisation like 5 IBU TDU is required for flavour retention. Alternatively, that such beers make good candidates for the more difficult procedure of sterile filtration and filling as the means of bio-load reduction for 'stabilisation'.

ED: TDU - Thermal Degradation Units

 

[manticle]

5IBU or 5 TDU?

Otherwise, I can make sense of what you are saying. Acceleration of oxidation/staling reactions may be a factor due to chilling process (along with a myriad of other possible culprits).

 

[of mice and gods]

Great info Bizier, cheers!

And it makes sense too. We go to the trouble of storing our beer in a cool area to prolong flavour, if you think about it, 'no chilling' (of which I claim to be no scholar) you're giving everything a super headstart to begin the degradation process through a multiplying factor relevant to time at certain temperatures?

Or am I drinking too much? Either way, thanks mate for the info.

Al

 

[Spiesy]

"our water tank which sits around 22-24 deg"

Yeah, I can see how this would work.

Well played.

 

[Spiesy]

I noticed an improvement in my hoppiness after I started purging my kegs with CO2.
My process is to clean out multiple kegs with a scrubby pad then fill the keg with sanitiser. I displace the sanitiser with the CO2 bottle and move it from one keg to the next using a keg transfer line. By the end all the kegs are clean and purged.

If I was worried about further O2 pick up I'd probably try keg conditioning. Once the yeast has settled you would never know the difference.

What does your keg cleaning process have to do with purging O2 from a beer filled keg, with CO2?

And are they keggers out there who actually don't purge with CO2? Are they mad? Or have I missed something?

 

[jphowman]

What does your keg cleaning process have to do with purging O2 from a beer filled keg, with CO2?

And are they keggers out there who actually don't purge with CO2? Are they mad? Or have I missed something?

When I first got my keg system I went through a couple of different processes.

First, I simply washed the keg, quickly shook ~0.5L of sanitiser around in it, poured it out and filled the keg with beer. As a new brewer I was expecting the CO2 blowing off the beer to keep a 'blanket' on it, eventually displacing the headspace.

Second, once told I should be purging my kegs I tried pressurising the keg, leave it for a while, then vent it from the top. Aside from being ineffective I thought this was a waste of gas.

Third, the process described above.

It was a stab at what may have been wrong. Feel free to ignore.

 

[Bizier]

5IBU or 5 TDU?

Otherwise, I can make sense of what you are saying. Acceleration of oxidation/staling reactions may be a factor due to chilling process (along with a myriad of other possible culprits).

Apoligies, I was on phone waiting for GF out and about. 5 PU (pasteurisation units). Ideally achieving those PUs with fewest TDU.

 

[Bizier]

Please note that I am not saying this is definitely the culprit here, but loss of the finer hop aromatics is typical of rapid oxidation reactions associated with high temps. I am just pointing out that attention to O2 reduction and minimising times at warm temperatures would be a good place to start.

Dave needs to report back on changes to his process to see if anything makes a perceivable difference.

 

[hoppy2B]

Flavour stability can be influenced to a high degree by the strain of yeast you employ to ferment your beer.

 

[bum]

Surely only compared to other yeasts? It won't reverse what is (debatably) bad brewing practice?

 

[manticle]

Flavour stability can be influenced to a high degree by the strain of yeast you employ to ferment your beer.

Tell me more.

 

[slash22000]

Flavour stability can be influenced to a high degree by the strain of yeast you employ to ferment your beer.

I imagine you mean during fermentation? How would yeast continue to effect a flavour stability once fermentation was complete (aside from the esters etc it leaves behind)?

 

[hoppy2B]

I imagine you mean during fermentation? How would yeast continue to effect a flavour stability once fermentation was complete (aside from the esters etc it leaves behind)?

I think you really need to research wine yeasts to have that question answered properly.
In general the descriptions for wine yeast go into a lot more detail with relation to the products of fermentation and how these affect the quality of the finished wine. Some wine yeast strains are better at producing wines suitable for aging and others produce wine more suited to early consumption.
With regard to beer yeast, I find one of the more frequently recommended yeasts on here, us05, to be excellent at highlighting hop flavour, but the resultant flavour tends to be a bit unstable.
In a nutshell, both wine and beer yeast assimilate various elements within the beer or wine in different ways. Some yeasts produce a beverage which is more stable.
SN9 is a commonly available wine/cider yeast which I have found produces a beer with very stable flavour. Its also quite neutral but gives some body and mouth feel.

 

[hoppy2B]

Surely only compared to other yeasts? It won't reverse what is (debatably) bad brewing practice?

Yes that is what I meant. Most experienced brewers have good brewing and sanitation practices.