Heriot-Watt Brewing and Distilling course

[hoppyscotty]

Larger breweries will be investing in glycol for chilling so despite their huge volumes will have much more chilling capacity on hand than we do with our tap-water driven chillers.

Was listening to a pro brewer on a podcast recently and they said that to achieve whirlpool temp they liquor back with cold water from their CLT, so that sounded like a neat solution to boost volume and manage temps.

 

[Agentgonzo]

Larger breweries will be investing in glycol for chilling so despite their huge volumes will have much more chilling capacity on hand than we do with our tap-water driven chillers.

For maintaining fermentation temperatures, I would expect glycol etc.

But for initially dropping the wort temp, I thought they used a large heat exchanger and tap water (at least the tours I've seen do). Cold tap water comes in, cools the wort and the exiting hot water goes into the HLT. Much more efficient (energy wise) than glycol and then extra energy to heat the HLT.

 

[hoppyscotty]

Bigger commercial breweries direct cooling straight from the chiller maybe via a CLT - They need to be able to cool wort at the rate of the biggest baddest pump they can get their hands on. Driving past Molson Coors in Burton On Trent and seeing the rows of multi story fermenters they have, then you'd need some serious flow rate to pump the wort into the fermenter or it'd take days to fill. Time is money so they don't mess around waiting for wort to cool. Also product quality and consistency is important and time to cool wort is a massive variable in the process that will impact final flavour and bitterness if you can't control it precisely. I suspect such systems wouldn't be cost effective on the typical micro brewery scale. I've never seen it on any of the craft brewery tours I've been on, but they're tiny compared to the big boys. Maybe pulling tap water from a cold liquor tank for cooling.

 

[Sadfield]

I'd have thought most large breweries boil using indirect steam or super heated water, and can pump cold water through the same system to cool to 80-85°C quickly, for whirlpool*/steeping hops. It would be the most efficient point to reclaim heat to fill the hlt, or use for cleaning. Followed by water then glycol with a plate chiller on transfer.

*There's a Charles Bamforth interview where he pretty much says Carling use the whirpool to get the correct level of DMS, to meet the flavour profile customers expect.

 

[hoppyscotty]

I don't know but I've stumbled across websites for companies selling massive chiller units the size of houses for large breweries for the purposes of chillers - the bigger ones are two stage, so they initially use water from the cold liquor tank (at a chilled temp) so I'd guess at maybe 10 degrees or so, then part way through switch to coolant direct from the chillers. They also provide cooling needs for other things around the breweries.

 

[Twostage]

Oh and the SG dropping to target is not even close to when fermentation is done.

This line stayed with me so I've finally got round to revisiting 'Yeast' from the Brewing Elements series. I'd be interested if it matches what you've learned @DocAnna .

In the fermentation chapter it talks about diacetyl (always have to type that one deliberate letter at a time) rest. Interesting re-read. Basically it says with lager it should be done for the last third or 2-3 days of fermentation. I know people on here are already doing that. I'd assumed I could wait until it was finished, apparently not. It also advises to chill slowly to the lager stage, not crash. With beer diacetyl rest it again mentions two days but does say that with a vigorous fermentation there won't be much about. It says there is a simple test (which I'm going to try) - take two samples in glasses, cover with tin foil and warm one sample to 60-70c for 10-20 minutes. If the warmed one smells of butter it needs a bit more time, if they both do it needs a lot more time.

One of my recent brews I pitched on the 7th and bottled on the 10th. Fermentation had stopped dead on the 9th. So it had a one day diacetyl rest. Never bottled that fast before but I just had a feeling it was OK (maybe my nose was telling me). Tasted a sample bottle last night and its very nice so fast bottling worked in this instance.

 

[Sadfield]

It also advises to chill slowly to the lager stage, not crash.

It's funny how some won't let their fermentation fluctuate more than ±0.1°C for fear of stress related off flavours, etc, then enforce a 20°C drop in the least amount of time possible.

In relation to DocAnna's point, this is an interesting place to start for those that don't have the Yeast book.

https://byo.com/article/fermentation-time-line/

 

[Twostage]

This line stayed with me so I've finally got round to revisiting 'Yeast' from the Brewing Elements series. I'd be interested if it matches what you've learned @DocAnna .

In the fermentation chapter it talks about diacetyl (always have to type that one deliberate letter at a time) rest. Interesting re-read. Basically it says with lager it should be done for the last third or 2-3 days of fermentation. I know people on here are already doing that. I'd assumed I could wait until it was finished, apparently not. It also advises to chill slowly to the lager stage, not crash. With beer diacetyl rest it again mentions two days but does say that with a vigorous fermentation there won't be much about. It says there is a simple test (which I'm going to try) - take two samples in glasses, cover with tin foil and warm one sample to 60-70c for 10-20 minutes. If the warmed one smells of butter it needs a bit more time, if they both do it needs a lot more time.

One of my recent brews I pitched on the 7th and bottled on the 10th. Fermentation had stopped dead on the 9th. So it had a one day diacetyl rest. Never bottled that fast before but I just had a feeling it was OK (maybe my nose was telling me). Tasted a sample bottle last night and its very nice so fast bottling worked in this instance.

Did the diacetyl test on my latest brew and it passed (both my nose and SWMBO's). In no rush to bottle this one, though, its for the Christmas festivities.

Just doing my homework on how to brew a Helles and found a somewhat easier way to do the test - "put it in the microwave for about 10 seconds". Wish I'd read that before messing about with water baths, thermometers and two samples. It did give me the opportunity to take a gravity reading though - 1.013 down from 1.058.

Need to get my hands on a Helles I think.

 

[DocAnna]

This line stayed with me so I've finally got round to revisiting 'Yeast' from the Brewing Elements series. I'd be interested if it matches what you've learned @DocAnna .

In the fermentation chapter it talks about diacetyl (always have to type that one deliberate letter at a time) rest. Interesting re-read. Basically it says with lager it should be done for the last third or 2-3 days of fermentation. I know people on here are already doing that. I'd assumed I could wait until it was finished, apparently not. It also advises to chill slowly to the lager stage, not crash. With beer diacetyl rest it again mentions two days but does say that with a vigorous fermentation there won't be much about. It says there is a simple test (which I'm going to try) - take two samples in glasses, cover with tin foil and warm one sample to 60-70c for 10-20 minutes. If the warmed one smells of butter it needs a bit more time, if they both do it needs a lot more time.

One of my recent brews I pitched on the 7th and bottled on the 10th. Fermentation had stopped dead on the 9th. So it had a one day diacetyl rest. Never bottled that fast before but I just had a feeling it was OK (maybe my nose was telling me). Tasted a sample bottle last night and its very nice so fast bottling worked in this instance.

Well I now know not to refer to diacetyl but instead to Vicinal Diketones - which probably doesn't help with typing it . There are two of these VDKs which both have butterscotch type flavours and are formed when alph acetohydroxy acids are excreted out of the cells, where they undergo oxidative decomposition to VDKs. They are produced during primary fermentation mostly - when the yeast is growing at the start as it normally requires oxygen to produce in the mitochondria. Removal relies on active yeast in suspension to metabolise it into 2,3-butanediol which has a much higher sensory threshold so you don't taste it. That also means yeast don't technically make diacetyl - rather it is formed outside of the cells.

Short and less wordy version shown in the graph below (which I really hope is ok to reproduce here). The VDKs are only just past the highest level as the SG reaches target. A 48 hour 'diacetyl rest' is used to help remove them, but the rate of removal will be temperature dependent. Soo... if you crash chill as soon as target SG is reached, you'll drop the yeast out of suspension and massively slow the rate of removal. This makes so much more sense now of why in a lager diacetyl rest the idea of raising the temperature at the end. By that time the flavour compounds of fermentation are complete, most of the carbohydrate sources are used up so you're not going to get esters either when raising the temperature, but the rise in temperature releases CO2 from solution, improving yeast suspension as it rises, and improves speed and effectiveness of VDK removal!

One of the things I am enjoying about this course is the 'Ah hah' moments when these empirical practices suddenly make so much sense. One of the things I am not enjoying is the word salad of chemical terms for this module. I realise I've been reading the same paragraph over for about 5 minutes and it's still not making more sense.

 

[Wynne]

Copying the chart should be fine as long as you reference the original work from which you copy it.

 

[Twostage]

Well I now know not to refer to diacetyl but instead to Vicinal Diketones - which probably doesn't help with typing it . There are two of these VDKs which both have butterscotch type flavours and are formed when alph acetohydroxy acids are excreted out of the cells, where they undergo oxidative decomposition to VDKs. They are produced during primary fermentation mostly - when the yeast is growing at the start as it normally requires oxygen to produce in the mitochondria. Removal relies on active yeast in suspension to metabolise it into 2,3-butanediol which has a much higher sensory threshold so you don't taste it. That also means yeast don't technically make diacetyl - rather it is formed outside of the cells.

Short and less wordy version shown in the graph below (which I really hope is ok to reproduce here). The VDKs are only just past the highest level as the SG reaches target. A 48 hour 'diacetyl rest' is used to help remove them, but the rate of removal will be temperature dependent. Soo... if you crash chill as soon as target SG is reached, you'll drop the yeast out of suspension and massively slow the rate of removal. This makes so much more sense now of why in a lager diacetyl rest the idea of raising the temperature at the end. By that time the flavour compounds of fermentation are complete, most of the carbohydrate sources are used up so you're not going to get esters either when raising the temperature, but the rise in temperature releases CO2 from solution, improving yeast suspension as it rises, and improves speed and effectiveness of VDK removal!

One of the things I am enjoying about this course is the 'Ah hah' moments when these empirical practices suddenly make so much sense. One of the things I am not enjoying is the word salad of chemical terms for this module. I realise I've been reading the same paragraph over for about 5 minutes and it's still not making more sense.

View attachment 91247

I'd seen VDKs mentioned (why do I think of an alcopop). Can't quite tell which line is yeast and which is diacetyl from the chart but I think the lighter one being diacetyl makes sense as it is being 'processed' out but yeast will remain in suspension.

Thinking about it, it is cold crashing which drops the yeast out that is the problem. Bottling 'early' will still have yeast in suspension so they can carry on doing the 2,3-butanediol (cut and pasted that to avoid typing with my tongue out) conversion. I also wonder what the affect of adding priming sugar is as it will re-activate the yeast and make them more active.

IF you had a brew that was going exactly follow that chart you could bottle around 70 hours (so there was still about 6-7 gravity points to go so no need to prime) and then it would be fizzed up and drinkable by 150 hours or lunchtime on day six. I'm tempted

 

[Jim Brewster]

Can't quite tell which line is yeast and which is diacetyl from the chart but I think the lighter one being diacetyl makes sense as it is being 'processed' out but yeast will remain in suspension.

Yes the lighter one is diacetyl, the label isn't in the best place. It initially lags behind suspended yeast count, which is logical.

I don't brew with lager yeast (not yet anyway), so not much of an issue for me but I do enjoy a graph

 

[DuncR]

Wow, fantastic thread but I think I now need to lie down in a darkened room!
Keep the information coming folks. Still scratching my head as to how best to time the start of my d-rest.

 

[DocAnna]

I’ve been lax in the updates here - in part because the new HW regulation for students prohibits publishing answers or information that can be used by other students as this is indirect fraud. Sooo … being a wee bit cautious about posting. The second assessed piece on the course was technically complex, involving graphical analysis of taste profiling panels and brew sheet data.
One of the huge takeaways is that small errors/ changes in process can have major impacts on the taste of the beer. My impression is that the timing of actions around the end of the boil are really critical, just a few minutes difference in actions will mean a beer deviates from spec.

The last assessment is a detailed analysis of the causes of acetalaldehyde in a lager beer brewed at high gravity then diluted down for production. I think I know all the factors, from oxygenation, yeast generations, magnesium, and zinc levels … and a few more. But getting it all down on paper feels a challenge. I’ve 2 weeks so need to get a wiggle on!

 

[Northern_Brewer]

The last assessment is a detailed analysis of the causes of acetalaldehyde in a lager beer brewed at high gravity then diluted down for production.

...so you're applying for that job at Carling then?

 

[Twostage]

I’ve been lax in the updates here - in part because the new HW regulation for students prohibits publishing answers or information that can be used by other students as this is indirect fraud. Sooo … being a wee bit cautious about posting. The second assessed piece on the course was technically complex, involving graphical analysis of taste profiling panels and brew sheet data.
One of the huge takeaways is that small errors/ changes in process can have major impacts on the taste of the beer. My impression is that the timing of actions around the end of the boil are really critical, just a few minutes difference in actions will mean a beer deviates from spec.

The last assessment is a detailed analysis of the causes of acetalaldehyde in a lager beer brewed at high gravity then diluted down for production. I think I know all the factors, from oxygenation, yeast generations, magnesium, and zinc levels … and a few more. But getting it all down on paper feels a challenge. I’ve 2 weeks so need to get a wiggle on!

Awww, no fair - I want details.

We should set up a mailing list so you can still keep us up to date without breaking the publishing rules

Seriously, though, I'm sure we can wait until after the submission deadline.

 

[DuncR]

I’ve been lax in the updates here - in part because the new HW regulation for students prohibits publishing answers or information that can be used by other students as this is indirect fraud. Sooo … being a wee bit cautious about posting. The second assessed piece on the course was technically complex, involving graphical analysis of taste profiling panels and brew sheet data.
One of the huge takeaways is that small errors/ changes in process can have major impacts on the taste of the beer. My impression is that the timing of actions around the end of the boil are really critical, just a few minutes difference in actions will mean a beer deviates from spec.

The last assessment is a detailed analysis of the causes of acetalaldehyde in a lager beer brewed at high gravity then diluted down for production. I think I know all the factors, from oxygenation, yeast generations, magnesium, and zinc levels … and a few more. But getting it all down on paper feels a challenge. I’ve 2 weeks so need to get a wiggle on!

Always assumed (wrongly) that after 60 minutes boil, timings were no longer too critical. Is it possible (within publishing rules!) to give a brief summary of key cause & effects at this stage?

 

[Jim Brewster]

I would assume it's because as a percentage, 30 seconds extra on a 5 minute addition is quite a bit extra, so will throw off the IBU and flavour/aroma contributions by quite a bit.

 

[Agentgonzo]

I would assume it's because as a percentage, 30 seconds extra on a 5 minute addition is quite a bit extra, so will throw off the IBU and flavour/aroma contributions by quite a bit.

From a commercial perspective when transferring out of the kettle via a chiller and into a fermenter can take an hour, a 5 minute addition isn't really there for just 5 minutes

 

[DocAnna]

Oh that is such a huge relief, that is my latest brewing essay done and submitted on the wort boiling and fermentation module. I have not enjoyed this essay one bit at all, and I don’t think it is at the level of my last ones but I’m fed up with all things acetaldehyde! If anyone really wants to know about causes of acetaldehyde in lager fermentations then do please let me know.

Now I can start to do Christmas!