Brewing beer

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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 03:28

' ..........  A common temperature mentioned for ale yeast fermentation is 20 degrees C. I must emphasize that this is the temperature of the liquid in the fermenter, not the ambient temperature.

During active fermentation heat is generated so the temperature of the liquid in the fermenter will be higher than ambient.

Your temperature of 16 degrees C for ambient temperature could be just right to achieve the fermentation temperature of 20 degrees F............... '


https://www.beeradvocate.com/community/threads/what-is-the-best-temp-for-ale-fermentation.368808/

Gosh - it would have been nice had anyone told me that months ago.
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Re: Brewing beer

Postby HBS Guy » 14 Oct 2018, 08:34

Yeah, I liked to get ferment down to 18°C, which is why I brewed mostly in the winter.

I brewed a nice Russian Imperial Stout, just a little beer, only 12%abv, put it in the Bathurst competition. It didn’t win a title, poured without a trace of a head. However, a brewer from the Malt Shovel Brewery, makers of James Squire beers, finished at his table (all tables finished before Stout, a huge and popular category) came over to the stout table, poured out some of my RIS and tasted it, said “This is a clever beer!”

I know all this as I was staying with a brewstress friend (a real alewife, brewed the ale for the household) just outside Bathurst and was the steward for the stout table (brought each beer in a jug, blind tasting as it should be) made sure they had forms, crackers and water to cleanse palates etc.

When that Malt Shovel brewer said that about my beer that made me pretty proud I can tell you!

After the stout judging was over I spoke to that brewer. He said he detected a minute amount of autolysis (vegemite taste) which is usually due to heat. He said it wasn’t really a fault, just broadened the range of flavors. That beer fermented sitting on the floor of my garage—must have fermented pretty strongly and likely had a lot of yeast some of which autolysed causing a slight Vegemite flavor. Vegemite is just spoiled brewers yeast after all.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 10:47

HBS Guy wrote: ......... ferment down to 18°C ..........I


was that 18 degrees the ambient air temp or the wort temp?
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Re: Brewing beer

Postby HBS Guy » 14 Oct 2018, 16:23

Wort temp.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 16:56

how did you monitor the wort temp?
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Re: Brewing beer

Postby HBS Guy » 14 Oct 2018, 17:00

Strip thermometer stuck to the outside of the fermenter.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 20:28

I will reduce the temp next time. 17 degrees maybe

Am thinking the temp of the outside of the plastic fermenter is not the same as the temp of the wort inside.
Plastic is not a good conductor of temperature.





With the exothermic activity inside the fermenter, there may be a gradient of heat toward the center of the fermenter too.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 20:39

hhhhhhhhhhmmmmmmmmmm

HDPE - 0.45 Min Value (W/m.K)

https://omnexus.specialchem.com/polymer-properties/properties/thermal-insulation

Now, how do we work this out?
WHo knows physics ?
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Re: Brewing beer

Postby johnsmith » 14 Oct 2018, 20:43

Sprintcyclist wrote:hhhhhhhhhhmmmmmmmmmm

HDPE - 0.45 Min Value (W/m.K)

https://omnexus.specialchem.com/polymer-properties/properties/thermal-insulation

Now, how do we work this out?
WHo knows physics ?



let me know what you need and i'll see if wifey is feeling generous ...she good at that complicated maths stuff (and no good at simple maths)
FD.
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Re: Brewing beer

Postby HBS Guy » 14 Oct 2018, 20:52

Sprintcyclist wrote:I will reduce the temp next time. 17 degrees maybe

Am thinking the temp of the outside of the plastic fermenter is not the same as the temp of the wort inside.
Plastic is not a good conductor of temperature.





With the exothermic activity inside the fermenter, there may be a gradient of heat toward the center of the fermenter too.


Don’t overthink it.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 20:54

too late, I am an overthinker.
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Re: Brewing beer

Postby Sprintcyclist » 14 Oct 2018, 21:01

johnsmith wrote:
Sprintcyclist wrote:hhhhhhhhhhmmmmmmmmmm

HDPE - 0.45 Min Value (W/m.K)

https://omnexus.specialchem.com/polymer-properties/properties/thermal-insulation

Now, how do we work this out?
WHo knows physics ?



let me know what you need and i'll see if wifey is feeling generous ...she good at that complicated maths stuff (and no good at simple maths)


Thanks John,

I think if I set the temp at a lower temp than the last time, that will be a good experiment.
I have a baseline to work from now.
Calculating it is all well and good, but after that I will still just change the temp.
Often doing things empirically works well
Don't waster her time, but thanks


Feel as the activity changes, so should the temperature.
Early on, maybe 16 degrees, after 1 day, 17 degrees, after 2 more days 18 degrees.
Leave it there.
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Re: Brewing beer

Postby Sprintcyclist » 22 Oct 2018, 13:42

Good news, I was out last night and bought a $12 beer at a pub.
It was dreadful. Flat, no head, a burnt flavour and sickly sweet at the same time.

Had it been one of mine it would have been a stand out failure.
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Re: Brewing beer

Postby HBS Guy » 22 Oct 2018, 14:26

If the strip thermometer showed 18°C on the outside the beer turned out well, no nasty aromas/flavors.

Some yeasts, the liquid Scottish Ale Yeast 1728 and the Nottingham dry yeast can ferment at lower temperatures still. Contrarywise, the Saison liquid yeast needed to be kept warm, the batches I made and racked into a cube were conditioned in my warm study. Fermented down to 1002!
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Re: Brewing beer

Postby HBS Guy » 22 Oct 2018, 14:26

If the strip thermometer showed 18°C on the outside the beer turned out well, no nasty aromas/flavors.

Some yeasts, the liquid Scottish Ale Yeast 1728 and the Nottingham dry yeast can ferment at lower temperatures still. Contrarywise, the Saison liquid yeast needed to be kept warm, the batches I made and racked into a cube were conditioned in my warm study. Fermented down to 1002!

I saved the yeast cake into two small swing top bottles, made up two brewpacks (part mash) and gave a bottle of the yeast cake with each Pack.
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Re: Brewing beer

Postby Sprintcyclist » 08 Nov 2018, 09:04

Phew - my last 2 brews have turned out pretty well.
Some have a bit too much head, will experiment with amount of priming sugar.
Seems 1 carbonation drop or 3 gms of raw sugar per tallie is ok for dark ales.
IPA may do with 5 gms of raw sugar.

Does priming sugar give the head, or just the bubbles?

Current batch is using US-05 yeast instead of nottingham, took 2 weeks to ferment down, I forgot to aerate the wort.
Tasting samples while taking SG readings were good. Last sample after a diacetyl rest was very good.
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Re: Brewing beer

Postby MonkAtAWinery » 08 Nov 2018, 12:43

Protein puts a head on the beer, sugar gives bubbles.
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Re: Brewing beer

Postby Sprintcyclist » 15 Nov 2018, 19:56

Phew, found a good article on home brewing.

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



........... Fermentation Timeline
Yeast during beer fermentation is consuming wort sugars and turning that sugar into new yeast cells, ethanol, CO2, and flavor compounds.
Brewers are primarily concerned with flavor compounds.
To maximize the correct flavor compounds, it is helpful to know how yeast ferments beer.
Ale fermentation of brewer’s wort follows three phases: lag phase for three to 15 hours, exponential growth phase for one to four days, and stationary phase of yeast growth for three to 10 days.

Lag Phase: Three to 15 Hours After Pitching Yeast
When yeast are pitched into beer they begin a process of acclimation to the environment known as the lag phase. Yeast begin to uptake minerals and amino acids from wort.
Amino acids are used to build proteins. The amino acids that yeast either can’t obtain or can’t get fast enough from wort need to be manufactured by the yeast.
Much the same way that humans need 100 percent of essential vitamins and minerals to make it though the day, yeast cells also need 100 percent of their vitamins and minerals (nutrients) to make it through a fermentation properly nourished.
All-malt wort is an excellent source of nitrogen, vitamins, and minerals.
Most of the vitamins yeast need for proper fermentation are supplied in wort.
Some examples of necessary vitamins are riboflavin, insositol, and biotin.
Important minerals are phosphorous, sulphur, copper, iron, zinc, potassium, and sodium.
As the vitamins and minerals are taken up from wort, yeast begins to manufacture enzymes necessary for growth.
Wort can be supplemented with additional vitamins and minerals by using commercially available yeast nutrients, which will improve the health and performance of yeast.
Oxygen is rapidly absorbed from the wort during the lag phase.
The yeast need this oxygen to grow and to produce important cell wall constituents.
It is important to introduce enough oxygen into wort at the beginning of fermentation. Shaking the fermenter will, at best, add about half the recommended level of 10 parts per million oxygen into solution.

This will produce satisfactory fermentation results, but to make sure a healthy fermentation will take place, oxygen can be added to the fermenter with any of several commercially available systems.
The lag phase can be carried out at a higher temperature than the rest of fermentation because very few flavor compounds are produced.
Ethanol production is also very limited, therefore ester formation is not a concern.
Some brewers begin the lag phase for ales at 22° 24° C and complete the fermentation at 17 20° C.
This can be done successfully for lagers, starting the lag phase at 22° 24° C and lowering the fermentation temperature to 10° 13° C.
Brewers will not see any visible activity during the lag phase, hence the name.
This phase is very important in building new, healthy cells able to complete fermentation.

If too much yeast is pitched, this will decrease the lag phase, and each individual cell will not be as healthy at the end of fermentation.
Although it may be reassuring to see fermentation activity within one hour of pitching, it is not best for the yeast.
(It is very difficult for homebrewers to overpitch — even three pints of active slurry is not too much.)

Exponential Growth Phase: One to Four Days
As the yeast comes out of the lag phase, it starts to consume the sugars in solution.
CO2 is produced, which starts to dissipate through the airlock and create a surface layer of foam on the beer.
The exponential, or logarithmic, phase of yeast growth is now starting.
During this phase, the cell count increases rapidly and ethanol and flavor compounds are produced. Airlocks bubble like crazy during this time frame.
The aroma that escapes from the airlock of most neutral ale yeast fermentations has an olive smell. The exponential phase occurs because yeast rapidly consume sugar.
Wort sugar is consumed by yeast in a certain pattern. Glucose is used first, then fructose and sucrose. These are simple sugars and can be quickly shuttled into metabolism.
The glucose concentration in wort is roughly 14 percent of wort sugars.
Maltose is the centerpiece sugar of malt and is a very important flavor component.
It makes up 59 percent of wort sugars, and its use by yeast gives beer its characteristic flavors.

There are one to five genes in yeast DNA that “turn on” in response to maltose, allowing for fermentation by brewer’s yeast.
After maltose enters the cell through a special uptake mechanism, it is hydrolyzed into glucose units by maltase enzymes.
Glucose can then enter the normal metabolism cycle.
Maltotriose is fermented last.
This is a tricky sugar for yeast to digest, and some yeast ferment maltotriose better than others. Some strains of brewer’s yeast do not ferment maltotriose at all.
The more flocculent a yeast strain, the less maltotriose it tends to ferment.
The ability to ferment maltotriose gives each strain its characteristic attenuation range.
At the height of activity, the beer is said to be at “high kraeusen.”
The head of foam on top of the fermentation turns yellow to brown.
The colors stem primarily from precipitated malt and hop components.
Brown spots form from oxidized hop resins.

Stationary Phase of Yeast Growth: Three to 10 Days
At this point yeast growth slows down, and yeast enter into a stationary phase of growth. Most of the flavor and aroma compounds have been produced, including fusel alcohols, esters, and sulfur compounds.
The beer is referred to as green because it does not yet have the acceptable balance of flavors.
Beer is matured in the stationary phase of growth, also known as the conditioning phase. Yeast reabsorb diacetyl that was produced during fermentation, and hydrogen sulphide escapes from the top of the fermenter as a gas.
The kraeusen falls, and yeast begin to settle out, or flocculate.
It is important to check the degree of attenuation at this point (by measuring gravity) to confirm that the yeast has completed fermentation.
Some strains of yeast begin to flocculate before terminal gravity has been reached and need to be “roused” back into solution.
Professional breweries cool the contents of the fermenter gradually to 35° to 40° F, which forces most of the yeast to flocculate. Most homebrewers do not have the facilities to do this, so they must wait for the fermenter to “clear.”
If the homebrew is to be bottled, flocculation can be allowed to complete in the bottles. ..............
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Re: Brewing beer

Postby HBS Guy » 15 Nov 2018, 22:09

That is where a 20L plastic water container aka a “cube” comes into its own. Rack the beer using a plastic hose fitted over the tap of the fermenter into the cube leaving most of the yeast cake behind. Seal the cube, bung into the fridge for a couple weeks, lots more yeast settles out.

I used a luggage tag to describe the beer incl OG & FG, date pitched/racked. Loop a rubber band through the hole in the tag, the rubber band can fit over the airlock and once racked the rubber band on the tag can be looped around the handle of the cube.

Notice all the proteins and lipids the yeast gets from the wort—now you see why an all–malt wort gives stronger, cleaner ferments. Of course, at the end of the ferment the yeast is basically swimming in a septic tank—both alcohol and CO2 are waste products of the yeast. Hence the need to make nice big starters to even pitching a second wort on top of the yeast cake from a previous ferment for pitching into high gravity worts.
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