Author Topic: Measuring gravity and stopping at the right time  (Read 12728 times)

Offline MRMARTINSALES

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Measuring gravity and stopping at the right time
« on: April 10, 2013, 08:56:04 AM »
All,

2 questions:

1, How do i measure very accurately the gravity of my beer? refractometer readings are too unreliable and hard to read at times. would a hydrometer be better?

2, How do people monitor their fermentation so that they stop it at the right time for the required alcohol. Sometimes imine is nearly there last thing at night and by time i get up the next morning it has gone over.

Please help - a commercial brewer may be able to shed some light. thanks

Offline philm63

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Re: Measuring gravity and stopping at the right time
« Reply #1 on: April 10, 2013, 01:08:37 PM »
During the brewing process, a refractometer is probably the simplest way to record SG. I'll check my refractometer every so often with distilled water to ensure it is calibrated properly, and will also cool my wort samples to approximately room temperature to be sure I am getting the most accurate reading. I also keep the refractometer's working surfaces meticulously clean and use a strong light source (sunlight when possible) to ensure clear readings.

Once the wort is in the fermentor and I've pitched the yeast, I'll take a sample from the fermentor and place it in a graduated cylinder and measure the OG with my hydrometer - I won't always get the same OG as I do with the refractometer, but I don't use my refractometer to track fermentation so that discrepancy does not matter to me. I'll stick with the hydrometer for fermentation readings from OG to FG.

After activity has slowed to a crawl, I'll check that sample again, and then again a day later to confirm fermentation has stopped and I'll record the FG and calculate my ABV accordingly, and let the yeast finish cleaning up for a few more days before packaging or moving to a secondary.

The finishing gravity I end up with is what it is; I won't try and stop it somewhere just to limit it to a specific ABV - I let the fermentability of the wort, the yeast strain and fermentation conditions determine my FG. Stopping fermentation before the yeast have completed their job is never a good idea, IMHO.

Assuming you are either an all-grain or partial-mash brewer and can control the fermentability of your wort to a reasonable degree; you can set the FG where you want by yeast selection and fermentation conditions and, based on the fermentability of your wort and your starting gravity, you can pretty much nail the ABV anywhere you want (within reason, of course).
On Tap: Oatmeal Stout, IPA
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On Deck: Kolsch

Offline MRMARTINSALES

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Re: Measuring gravity and stopping at the right time
« Reply #2 on: April 20, 2013, 03:03:41 PM »
Thanks for the latest reply. I see 71 people have viewed this post and I would appreciate some more responses. I'm trying to just keep this alive

Offline 88Q

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Re: Measuring gravity and stopping at the right time
« Reply #3 on: April 20, 2013, 04:34:53 PM »
No need - The above post said it all
88Q

Offline MRMARTINSALES

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Re: Measuring gravity and stopping at the right time
« Reply #4 on: April 21, 2013, 02:45:31 AM »
That's fair enough however commercial brewers ned to produce the same abv beer every time they can't have the same name beer coming out at different abv each week. So I just wanted to know how they stop it exactly at the same abv each time.

Offline brewfun

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Re: Measuring gravity and stopping at the right time
« Reply #5 on: April 21, 2013, 04:20:00 AM »
Commercial brewers don't do anything different than what Philm63 said.

Commercial brewers use the same brewing technique on each batch to ensure consistency.
Beer Appreciation is the space between pints.

Offline ihikeut

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Re: Measuring gravity and stopping at the right time
« Reply #6 on: April 21, 2013, 06:08:51 AM »
I am not a commercial brewer but I believe they adjust the beers finale ABV by adding sterile water after the fermenting process

Offline MRMARTINSALES

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Re: Measuring gravity and stopping at the right time
« Reply #7 on: April 21, 2013, 03:11:56 PM »
Would that not weaken the taste of the beer?

Offline Maine Homebrewer

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Re: Measuring gravity and stopping at the right time
« Reply #8 on: April 21, 2013, 04:33:33 PM »
Here's my understanding of how a commercial brewery gets the same thing every time.

After sparging, gravity and volume are read.   From that a boil time to achieve expected final gravity is calculated, as well as the hop amounts to bitter and flavor the newly calculated final volume.  I don't know how exactly they do it. I imagine that they've got charts.

Homebrewers tend to have ingredients and boil times (sometimes volumes) as constants, and the flavor and alcohol are somewhat variable.

Whereas the commercial brewer has flavor and alcohol as constants, so hops, final volumes and boil times are variable.
« Last Edit: April 21, 2013, 07:16:50 PM by Maine Homebrewer »
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Offline beernbourbon

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Re: Measuring gravity and stopping at the right time
« Reply #9 on: April 21, 2013, 05:40:30 PM »
That's fair enough however commercial brewers need to produce the same abv beer every time they can't have the same name beer coming out at different abv each week. So I just wanted to know how they stop it exactly at the same abv each time.

Philm hit it spot on.
Actually, the 'exact' ABV isn't. The laws/regulations specify a range of X.X to Y.Y, (6% ABV could be anywhere from 5.7 to 6.2....are you really going to be able to taste the difference in 1/2%? Most likely not) and the grains, times, temps are all controlled to the minutia, to extract the highest efficiency for the dollar. They are in it to make money, we are in it to get great taste. CB's have adapted a science to the art, ie...they have formulae, charts, etc for EVERYTHING, so that every batch is as close to perfect as possible for what they are brewing.
The wives tales of adding water are just that. THAT you would taste. There is a distinct difference between brewing a low gravity beer and brewing a higher gravity beer and adding water to get to a certain ABV....try it. It TASTES watered down, no question.
Primary 1: Nada
Primary 2: Zip
Primary 3: Zilch
Aging: Four hops 60 min IPA #3, #4, #5
Fridge/drinking:Chocolate Milk Stout, Four Hops #1, #2, Bunny Banger 90 min IPA #1, #2, Mowin Down a Thirst,
Next up: Headin' for stout season....

Offline Maine Homebrewer

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Re: Measuring gravity and stopping at the right time
« Reply #10 on: April 21, 2013, 07:28:20 PM »
Quote
They are in it to make money, we are in it to get great taste.

How does one make money if not by producing something that pleases people enough that they'll pay for it? 

I brew because 45% of the price of a commercial beer is tax, and because what I make isn't half bad.

"To alcohol! The cause of - and solution to - all of life's problems!" -Homer Simpson

Offline brewfun

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Re: Measuring gravity and stopping at the right time
« Reply #11 on: April 21, 2013, 08:46:39 PM »
Wow! Lots of speculation.

I am a commercial brewer. Been my full-time paycheck for more than a decade. I'll repeat what I said, earlier:

"Commercial brewers don't do anything different than what Philm63 said.
Commercial brewers use the same brewing technique on each batch to ensure consistency."


That means that the grain bill, mash, sparge, boil, whirlpool, chilling and fermentation are identical for each batch. pH and gravity is measured at several points.

Within that, there are acceptable variations. Many breweries will conduct a congress mash on a new malt batch, and make grain bill adjustments, from there. Hops are used in a timely fashion, so aging is not an issue after a box is opened. One popular brewery I know of, will not use an opened box of hops for dry hopping, even if it's only been for a few hours. Fermentation and pH are monitored daily, or very close to it. Yeast cell counts are taken to ensure viability.

We're allowed an abv variation of +/- 0.2%. You honestly cannot taste a difference of less than 5 IBUs. This has been tested over and over.

For scaling volume, multiple batches are blended into fermenters and bright tanks. This smooths out the kettle variations. Many breweries quickly size up fermenters to hold 4 or more batches. One mega-brewer said they package 4 bright tanks at a time, each of those held 10 fermenters and each fermenter held 6 batches. That'll fix consistency, right there.

I have lots of critical control points that help me monitor and guide a batch of beer. For one thing, I monitor the grain crush, mash thickness and sparge rate very closely. I expect my efficiency to be in the 92 - 94% range. Sure, malt is cheap, but with lower efficiency, it doesn't take long to use up grain that could make up another full batch. A huge potential sales loss. Each batch is the same size, with the same boil time.

Part of the fun of homebrewing is learning bits about commercial brewing, seeing if it can be applied to your setup, then changing it at-will to suit your needs. Unless you're really into competitions, consistency really isn't much of an issue. Even then, there are articles and books that outline how to blend on a homebrew scale.
Beer Appreciation is the space between pints.

Offline Slurk

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Re: Measuring gravity and stopping at the right time
« Reply #12 on: April 22, 2013, 01:25:24 AM »
I have lots of critical control points that help me monitor and guide a batch of beer. For one thing, I monitor the grain crush, mash thickness and sparge rate very closely.

Thanks for your answer brewfun!

Question: As a commercial brewer, what do you consider as the most critical fase/element/ingredient or where do you have less process control?

R, Slurk
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Offline beernbourbon

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Re: Measuring gravity and stopping at the right time
« Reply #13 on: April 22, 2013, 07:49:42 PM »
How does one make money if not by producing something that pleases people enough that they'll pay for it? 
I brew because 45% of the price of a commercial beer is tax, and because what I make isn't half bad.

As to your first line....well, some would call me rather 'anti-establishment at times. Long and short, people will buy mass market because they don't know better, until they do. I couldn't stand beer, until I discovered it was the garbage I was drinking, not beer as a whole. Once I discovered beer actually has taste, game on. There is a whole soap box for me to stand on, in reference to this, but this is not the time nor the place.
As to the second... I brew to drink better tasting beer. Call me a beer snob. Same with my bourbon. If I'm going to be paying hard earned money for a recreational beverage, it dam well better taste amazing. (Yeah....not there yet, but one must pursue perfection, right? ;D...mine hasn't even begun to reach the 'half bad' status yet, but, I'll keep a-learnin)

Wow! Lots of speculation.
I am a commercial brewer. Been my full-time paycheck for more than a decade. I'll repeat what I said, earlier:
"Commercial brewers don't do anything different than what Philm63 said.
Commercial brewers use the same brewing technique on each batch to ensure consistency."


Yes, my 'numbers' may not be exact, but I believe my point...which was there is a range that you are required to meet (I was not aware it had to be THAT close....0.2%...wow) was accurate, and you must use the tools available to you to meet that range. We only meet self imposed 'ranges' or designs. I was not, nor would ever, intentionally throw out information I had not checked, with the intention to mislead. My apologies if I did so.  :-X

I second Slurks question.... what is the least controllable factor for you as a commercial brewer.
Primary 1: Nada
Primary 2: Zip
Primary 3: Zilch
Aging: Four hops 60 min IPA #3, #4, #5
Fridge/drinking:Chocolate Milk Stout, Four Hops #1, #2, Bunny Banger 90 min IPA #1, #2, Mowin Down a Thirst,
Next up: Headin' for stout season....

Offline brewfun

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Re: Measuring gravity and stopping at the right time
« Reply #14 on: April 24, 2013, 08:09:33 AM »

Question: As a commercial brewer, what do you consider as the most critical phase/element/ingredient or where do you have less process control?

R, Slurk

Honestly, I have the least control over my employees. If they eff up, I have to live with the consequences. Second to that, is how the beer is stored/sold/served. I train and have specific written procedures, but at the end of the day, they're individuals and circumstances I just can't lose any sleep over. 

As for what I put my hands on, I have the least control over hops. I have to order them two years in advance, based on guesses about aroma and bittering potential. Then get shorted and perhaps grow faster than anticipated. It leads to some interesting strategies for flavor and aroma. Myself and many other breweries have taken to building 80% of the bittering with the first addition then skipping to higher dosing of later additions, to maximize flavor/aroma impact with less volume. Newer recipe designs are skipping anything in the 50 - 20 minute range.

The most important point of control is fermentation and yeast health. That's a topic discussed over and over on these forums with great information and depth. I have the additional task of getting 12+ generations out of my yeast, simply to control costs.
Beer Appreciation is the space between pints.