Hazelwood Brewday

[Hazelwood Brewery]

It’s done. The gravity turned out to be 1056 in the end so I’m expecting something between 5.5% and 6.0% ABV.

In the hopstand I used Cascade because this hop is particularly high in those bound thiols. I also used some Citra because that too is high in bound thiols. These bound thiols should be released through bio-transformation over the next three days or so.

Speaking of bio-transformation, Citra is also high in essential oils geraniol and linalool, the latter being transformed into citronellol - another desirable oil. So I put 100g of Citra in my fermenter (to get these essential oils and the citronellol from the linalool) and poured the wort over them to give them a good soaking.

I’m using two packs of yeast together for this fermentation because there are two main bio-transformation processes going on - one to release the bound thiols and one to transform geraniol into citronellol (they do other stuff but these are the areas of most interest to me - oh yeah, alcohol! ). Each of these yeasts is a specialist in each of the two processes so together I’m hoping for the best result. I also added a little “yeast vit” to help them on their way.

After a quick stir, the fermenter is in the fermentation cabinet next to the Summer Breeze and my brew day is done - apart from the cleaning up.

 

[Hazelwood Brewery]

This beer will also get another dry hop addition on day 7 and again, it will be Citra.

Citra is a great all-rounder because as well as being high in bound thiols and essential oils, it’s also high in free thiols. These are the ones that are immediately available for use in dry-hopping.

The problem with these thiols is that once released they are volatile and the most volatile will be scrubbed out by the CO2 produced through fermentation. Adding another charge of dry-hops at the end of fermentation, when CO2 production is far less vigorous, allows more of these volatile thiols to stay in the beer.

A secondary benefit of late dry hopping is that some essential oils are not especially soluable in water but they are in alcohol and at the end of fermentation the alcohol is also at it’s highest.

 

[DocAnna]

This beer will also get another dry hop addition on day 7 and again, it will be Citra.

Citra is a great all-rounder because as well as being high in bound thiols and essential oils, it’s also high in free thiols. These are the ones that are immediately available for use in dry-hopping.

The problem with these thiols is that once released they are volatile and the most volatile will be scrubbed out by the CO2 produced through fermentation. Adding another charge of dry-hops at the end of fermentation, when CO2 production is far less vigorous, allows more of these volatile thiols to stay in the beer.

A secondary benefit of late dry hopping is that some essential oils are not especially soluable in water but they are in alcohol and at the end of fermentation the alcohol is also at it’s highest.

Oh for the want of a computerised gas chromatography system.. sigh , it would be really interesting to see what compounds were liberated from a dry hop and lost to the CO2 in the fermentation! At a pragmatic level it does make me wonder if you could take the CO2 through a sanitised blow off jar with either chilled water or vodka in it and see if it acquired the taste of the volatile compounds.

 

[Hazelwood Brewery]

Oh for the want of a computerised gas chromatography system.. sigh , it would be really interesting to see what compounds were liberated from a dry hop and lost to the CO2 in the fermentation! At a pragmatic level it does make me wonder if you could take the CO2 through a sanitised blow off jar with either chilled water or vodka in it and see if it acquired the taste of the volatile compounds.

One of these probably won’t happen but the other could - are you going to try it?

 

[Pennine]

I just read that thiols are retained better with fermentations done at lower temps, maybe stay at the very low end of the yeasts you are using?

Also can you get volatilized thiols back into solution?

 

[Hazelwood Brewery]

I just read that thiols are retained better with fermentations done at lower temps, maybe stay at the very low end of the yeasts you are using?

Also can you get volatilized thiols back into solution?

That’s right. I’m fermenting at 18C which is the lowest temperature for one of the two yeasts. I’ll add the dry hops on day 7 and put the fermenter in the main brew-shed at 12C for 2 days.

Your last point was also raised by Anna above, she was thinking about bubbling the CO2 laden with Thiols through some vodka to see if they can be recovered.

 

[Pennine]

That’s right. I’m fermenting at 18C which is the lowest temperature for one of the two yeasts. I’ll add the dry hops on day 7 and put the fermenter in the main brew-shed at 12C for 2 days.

Your last point was also raised by Anna above, she was thinking about bubbling the CO2 laden with Thiols through some vodka to see if they can be recovered.

Yeah that comment was in reference to her, would thiols get back into even alcohol just by bubbling through it. Might need to add some pressure and time to make it happen?

 

[Hazelwood Brewery]

Yeah that comment was in reference to her, would thiols get back into even alcohol just by bubbling through it. Might need to add some pressure and time to make it happen?

Ah! Understood!

 

[The-Engineer-That-Brews]

I'm unlikely to be aiming to replicate any of what you're doing here, but I'm absolutely loving the sense of invention and discovery :hat:
On the subject of the low mash pH, is it too simplistic to suggest it might be associated with the alpha acids in the hops - or is the quantity too low?

 

[DocAnna]

Yeah that comment was in reference to her, would thiols get back into even alcohol just by bubbling through it. Might need to add some pressure and time to make it happen?

I was thinking that the vapour would be much more soluble than the CO2 gas - which would require pressure and time. Vapour should condense quickly in the bubbles through a cold fluid, and while vodka would improve solubility, using ice cold water would likely be adequate.

Problem is that would require an interconnecting hole in my fridges to take the blow off tube into the cold side. I’m not really keen on drilling more holes in my fridges.

 

[Hazelwood Brewery]

I'm unlikely to be aiming to replicate any of what you're doing here, but I'm absolutely loving the sense of invention and discovery :hat:
On the subject of the low mash pH, is it too simplistic to suggest it might be associated with the alpha acids in the hops - or is the quantity too low?

I wondered the same thing myself. The quantity seems too low but maybe not. I’ll see what happens over the next few brews and maybe do some tests.

This science stuff is getting busy!

 

[pilgrimhudd]

I don't know why I do it to myself!

 

[Pennine]

I was thinking that the vapour would be much more soluble than the CO2 gas - which would require pressure and time. Vapour should condense quickly in the bubbles through a cold fluid, and while vodka would improve solubility, using ice cold water would likely be adequate.

Problem is that would require an interconnecting hole in my fridges to take the blow off tube into the cold side. I’m not really keen on drilling more holes in my fridges.

Ahh your right, you could feasibly do this in the freezer with vodka. Another problem is what do you do with hops infused vodka?

 

[Hazelwood Brewery]

Ahh your right, you could feasibly do this in the freezer with vodka. Another problem is what do you do with hops infused vodka?

What…would…you…do…?

 

[Hazelwood Brewery]

It's been a while since I looked at my temperature data loggers, this is the latest data over the last 20 days. The top chart shows data from all four loggers; external temperature, fermenting cabinet, brew-shed, and the exhaust from my glycol chiller. The charts below show the brew-shed and fermentation cabinet with a bit more resolution over the same period. For the first half of the bottom chart I have nothing fermenting and the temperature control was off and is then followed by two temperature settings for different beers.

Point A - I would prefer my chiller exhaust to not exceed 35C but I think that's inevitable as ambient temperatures exceed 25C for long periods unless I build some kind of water-cooled heat dump (not planning that yet).

Point B - Just an explanation for this spike, it's the warmth of my hand while handling the data logger to take readings.

Points C & D - This is where I was doing some work in the brew-shed but I need to figure out the explanation for why the temperature then went so much lower and why it look so long to settle after.

 

[DocAnna]

The resolution on your temperature monitoring is either wonderful or a bit disconcerting depending on perspective. Looking at this I'm not sure if I'd love to know how my fermenter temperature varies or whether ignorance really is bliss

What…would…you…do…?

As to the hop infused vodka - it could be very interesting as it might also contain a larger amount of the higher alcohols which might not be so good... but yes I did think your comment was very apt! I'm wondering how to do a sterile/sanitised blow off tube and vodka does have some merits in that it would stay bug free over time. Thinking cap time.

 

[Horners]

The resolution on your temperature monitoring is either wonderful or a bit disconcerting depending on perspective. Looking at this I'm not sure if I'd love to know how my fermenter temperature varies or whether ignorance really is bliss

As to the hop infused vodka - it could be very interesting as it might also contain a larger amount of the higher alcohols which might not be so good... but yes I did think your comment was very apt! I'm wondering how to do a sterile/sanitised blow off tube and vodka does have some merits in that it would stay bug free over time. Thinking cap time.

Not read the whole vodka thread above but just to comment that for all of my airlock needs I am working my way through the remains a cheap bottle of Lidl vodka someone brought to a party at ours. Takes the worry out of anything getting sucked back into the brew when cold crashing.

 

[Hazelwood Brewery]

The resolution on your temperature monitoring is either wonderful or a bit disconcerting depending on perspective. Looking at this I'm not sure if I'd love to know how my fermenter temperature varies or whether ignorance really is bliss

For the most part the temperature variation is only about 1 degree (as set on the temperature controller. Also remember this is 20 days elapsed time so the variation is slow-moving. That middle section where the fermentation cabinet is set at 20 degrees represents a week and each of the little saw-tooth traces of four or five peaks is a whole day with the longer slope/gap occurring overnight.

It doesn’t look so scary if I expand one day, this is the middle day in that same week. The lowest temperature of the day was 18.8 and the highest was 19.8. The rate of change when not being directly heated or cooled is between 0.08 and 0.2 degrees per hour.

 

[Hazelwood Brewery]

Just a quick post to confirm I’m not brewing Pathfinder today because we’re going out with friends this afternoon.

Maybe tomorrow.

 

[The-Engineer-That-Brews]

It's been a while since I looked at my temperature data loggers, this is the latest data over the last 20 days. The top chart shows data from all four loggers; external temperature, fermenting cabinet, brew-shed, and the exhaust from my glycol chiller. The charts below show the brew-shed and fermentation cabinet with a bit more resolution over the same period. For the first half of the bottom chart I have nothing fermenting and the temperature control was off and is then followed by two temperature settings for different beers.

View attachment 50486
Point A - I would prefer my chiller exhaust to not exceed 35C but I think that's inevitable as ambient temperatures exceed 25C for long periods unless I build some kind of water-cooled heat dump (not planning that yet).

Point B - Just an explanation for this spike, it's the warmth of my hand while handling the data logger to take readings.

Points C & D - This is where I was doing some work in the brew-shed but I need to figure out the explanation for why the temperature then went so much lower and why it look so long to settle after.

Very nice, Mr H I have found it quite illuminating to add measurements of the actual brews themselves too (in the Corny's and Fermenters). They are of course much MUCH more steady than the air temperatures - 25L of beer needs to absorb or discard about 105kJ of thermal energy to change temperature by 1ºc; and in the case of the fermenters can be a couple of degrees higher if they are going for it