boil time and original gravity

[bbedell]

I'm wondering if/how people here deal with the topic of adjusting boil time to meal a target OG.

I was doing a Helles brew last weekend, per the recipe I had the target OG was 1.055. The specific recipe was very non-specific on its boil steps, but did indicate a 1 hour boil, whereas most other Helles recipes I had seen recommended a 90 minute boil. Well, after 60 minutes I stopped the boil only to find that my gravity was 1.020. I decided to continue the boil for another 30 minutes, and added a bit more pale malt extract. After 30 more minutes the gravity was up to 1.050.

I'm wondering if it is recommended to proceed this way when trying to adjust to a target OG? Do you typically take a sample of the wart towards the end of the boil (rather than stopping the boil first) then let the sample cool and measure a gravity? The main concern I had was that I had added 60 and 5 minute hops to my boil, but then when the boil was continued for another 30 minutes these ended up being 90 and 35 minute hops...wondering if this is going to affect my outcome, and if so how can it be avoided? Also wondering how often people check a gravity post sparge/pre-boil and what kind of numbers should one be looking for in relation to target post-boil OG? I believe my post-sparge 6 gallon gravity was 1.014 with this batch (again looking to end with 5 gallons of wort at an OG of 1.055 per the recipe).

Any tips would be appreciated! Thanks

 

[xpops]

as you mentioned, the issue is with the hop additions. pushing your boil back would start messing with your IBU's which you probably don't want.

anytime i have not hit my OG, i leave it as it is. either the beer is stronger than i expected, or weaker than expected. take it as a learning opportunity to dial in your efficiency when planning future recipes.

i do take pre-boil gravities...it will always be lower than your OG, but it really depends on how aggressive your boil, and what your post boil volume is. I only use the pre-boil gravity as a "ball park" to know if i'm going to be close to my post boil OG nor not.

 

[bbedell]

Thanks for the reply. How do you find your pre boil OG compares to your post? Was 1.014 somewhat normal for a target of 1.055 and it simply required that extra boil time?

In this case, with a 1 hour boil OG of 1.020 I felt my only options were dump it or take meaures to try and save it. Wasn't looking to make a 1.5% beer at the end of the day. It's a Munich Helles recipe so let's hope the extra boil time doesn't screw up my IBUs

 

[geoffm33]

What was the volume when you stopped the boil after 60 minutes?

I don't think you would have hit 1.055 with 6 gallons at 1.014 unless you boiled down to ~1.5 gallons.

https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

 

[kh54s10]

I assume the Helles recipe used pilsner malt. It is common to boil pilsner malts for 90 minutes to drive off DMS which seems to be a factor in pilsner malts. The timing on the hop could vary greatly.

Volumes have the most effect on gravity. If you expected a 1.050 OG and boiled the amount for a 90 minute boil for only 60 minutes you would have too much wort at a low OG.

It sounds like you needed more information for this brew. Expected preboil amount compared to the time of the boil. For instance I need 7 gallons for a 5 gallon batch at 60 minutes and 8+ gallons for a 90 minute boil. The preboil gravity of the 60 minute boil would be a fair amount higher than for the 90 minute boil.

I use Beersmith, and even if I am doing someone else's recipe, I put it in to account for my equipment and procedures. The program gives volumes and predicted gravities..

 

[xpops]

Thanks for the reply. How do you find your pre boil OG compares to your post? Was 1.014 somewhat normal for a target of 1.055 and it simply required that extra boil time?

In this case, with a 1 hour boil OG of 1.020 I felt my only options were dump it or take meaures to try and save it. Wasn't looking to make a 1.5% beer at the end of the day. It's a Munich Helles recipe so let's hope the extra boil time doesn't screw up my IBUs

i'd have to be at home and look back at my notes...usually for a 60 min boil with a target of say...1.064, i may see 1.055 +/1 0.002...usually somewhere in the 8-12 points ball park. 1.014 is significantly low. either your volume was drastically higher (volume for a 10gal batch, but recipe for a 5gal batch??) or the efficiency was extremely low, maybe from grain crush?

 

[bbedell]

What was the volume when you stopped the boil after 60 minutes?

I don't think you would have hit 1.055 with 6 gallons at 1.014 unless you boiled down to ~1.5 gallons.

https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

Don't have a graduated boil kettle so can't measure volume until I transfer to fermenter. Starting volume pre boil was 6 gal. Finished just under 5 gal after 90 minutes. Not sure where it was after the first 60 min. I also added another 0.25-0.5 lb of malt extract during the last 90 min which I'm sure affected the OG

 

[doug293cz]

If you can't measure pre- and post-boil volumes in your BK, you will have trouble getting your process under control. You want your process to have predictability. Make yourself a dip stick. Pour measured amounts of water in your BK, and mark a rod (or just note depths on a ruler) at the various volumes.

Your measurements, both volume and SG seem to be all over the place. There is no self consistency among them. You need to make more accurate measurements to have any idea what is going on in your brewing, or for other to be able to give you informed advice. Hydrometer samples need to be cooled to below 100°F, and then readings compensated for actual temperature vs. the hydro's calibration temp (usually either 60°F or 68°F, should be on the paper in the stem.)

0.5 lbs of DME in 5 gal of 1.020 wort would only raise the SG to about 1.029, No way you could have gotten to 1.050 unless you added a lot more DME than your post indicates

Finally, 1.014 is an extremely low pre-boil gravity under any circumstances. It indicates that your process has terrible mash efficiency, and most of the low mash efficiency is probably due to low conversion efficiency. To net 5 gal of 1.055 beer from 6 gal pre-boil volume, you need a pre-boil SG of 1.046. Can you describe your brewing process in as much detail as possible, starting with the crushing of the grain?

Brew on

 

[bbedell]

Sure, and thanks for your detailed response. Below is a breakdown of my mash and boil, all calculations were done using the Green Bay Rackers calculator on their website.

2lb American 2 row pale palt
1lb Vienna malt
1lb dextrin malt
0.25lb 40deg L crystal malt
all were bought pre-crushed for me

-added grains to 5.3 qt of 168 degree water in tun to reach mash temp of 145 deg and let sit for 20 min. made sure to stir well at the start to avoid dough balls
-added 2.1 qt boiling water to tun to reach 162 deg and let sit for 40 min
-added 1.6 qt boiling water to tun to reach 170 deg and let sit for 5 min
-collected first runnings until liquid from tun was clear, making sure to add runnings back into tun after collecting, allowing grain bed to set
-started to sparge with 170 degree water. my general technique is to continuously add water to maintain a water level 1-2 inches above the grain bed. continued to sparge until I had collected 6 gallons of wort (my kettle boils off around 1 gallon per hour, so for a desired post-boil volume of 5 gallons this seems appropriate)

-added wort to brew kettle, added 4 lbs pale malt extract and then checked gravity (temp was not below 100 deg) which was 1.014 (note: I believe that gravity was after adding the pale extract, but my memory could be off and it could have been post sparge and pre-extract addition).
-started the boil, added 1oz perle pellets at 60 min and 0.5 oz of hallertau at 5 min, continued boil for 60 min
-post boil gravity (temp not below 100deg) was 1.020
-restarted boil, added additional 0.5lb of pale extract, continued boil for 30 more minutes
-after 30 more minutes, measured gravity at 1.050 (again, not cooled below 100 deg)

-cooled wort to 48 degrees, transferred to carboy, oxygenated with O2 tank and stone, added yeast starter and transferred to fridge at 50 degrees

thanks in advance for any and all insight you can offer.

beau

 

[doug293cz]

Sure, and thanks for your detailed response. Below is a breakdown of my mash and boil, all calculations were done using the Green Bay Rackers calculator on their website.

2lb American 2 row pale palt
1lb Vienna malt
1lb dextrin malt
0.25lb 40deg L crystal malt
all were bought pre-crushed for me

-added grains to 5.3 qt of 168 degree water in tun to reach mash temp of 145 deg and let sit for 20 min. made sure to stir well at the start to avoid dough balls
-added 2.1 qt boiling water to tun to reach 162 deg and let sit for 40 min
-added 1.6 qt boiling water to tun to reach 170 deg and let sit for 5 min
-collected first runnings until liquid from tun was clear, making sure to add runnings back into tun after collecting, allowing grain bed to set
-started to sparge with 170 degree water. my general technique is to continuously add water to maintain a water level 1-2 inches above the grain bed. continued to sparge until I had collected 6 gallons of wort (my kettle boils off around 1 gallon per hour, so for a desired post-boil volume of 5 gallons this seems appropriate)

-added wort to brew kettle, added 4 lbs pale malt extract and then checked gravity (temp was not below 100 deg) which was 1.014 (note: I believe that gravity was after adding the pale extract, but my memory could be off and it could have been post sparge and pre-extract addition).
-started the boil, added 1oz perle pellets at 60 min and 0.5 oz of hallertau at 5 min, continued boil for 60 min
-post boil gravity (temp not below 100deg) was 1.020
-restarted boil, added additional 0.5lb of pale extract, continued boil for 30 more minutes
-after 30 more minutes, measured gravity at 1.050 (again, not cooled below 100 deg)

-cooled wort to 48 degrees, transferred to carboy, oxygenated with O2 tank and stone, added yeast starter and transferred to fridge at 50 degrees

thanks in advance for any and all insight you can offer.

beau

If all you used was 4 lbs of DME (which has a potential of about 44 pts/lb) you would have 176 gravity pts. In 5 gal of wort, the DME by itself would give you an SG of:

SG = 1 + (176 / 5) / 1000 = 1.035​

So, clearly your post-boil SG measurement has some serious error.

Assuming your 1.014 pre-boil SG was taken before you added any DME, that represents a conversion efficiency of 50% - 60%. This is very low, since conversion efficiencies of 95% or better are possible with optimal mash conditions. The largest contributor to low conversion efficiency is too coarse a crush, such that conversion cannot reach the centers of the grits during the allotted mash time. In your case your mash temps may have also been an issue. 145°F is on the low side, and both gelatinization and enzyme action will be significantly slower than at higher temps. Conversely 162°F is on the high side, and denaturing of enzymes will be fairly rapid. And, unless you have calibrated your thermometer, the measured temps could be significantly in error.

Brew on

 

[bbedell]

If all you used was 4 lbs of DME (which has a potential of about 44 pts/lb) you would have 176 gravity pts. In 5 gal of wort, the DME by itself would give you an SG of:

SG = 1 + (176 / 5) / 1000 = 1.035​

So, clearly your post-boil SG measurement has some serious error.

Assuming your 1.014 pre-boil SG was taken before you added any DME, that represents a conversion efficiency of 50% - 60%. This is very low, since conversion efficiencies of 95% or better are possible with optimal mash conditions. The largest contributor to low conversion efficiency is too coarse a crush, such that conversion cannot reach the centers of the grits during the allotted mash time. In your case your mash temps may have also been an issue. 145°F is on the low side, and both gelatinization and enzyme action will be significantly slower than at higher temps. Conversely 162°F is on the high side, and denaturing of enzymes will be fairly rapid. And, unless you have calibrated your thermometer, the measured temps could be significantly in error.

Brew on

Thanks, Doug. Very informative stuff. I had been using a digital thermometer with previous brewing sessions, but it broke so I was using a normal "floating thermometer" for this session (did not leave it floating, but would insert it from time to time to take readings). Is it possible to calibrate this type of thermometer? I'm guessing you're referring to digital thermometers when you mention calibration, but wasnt sure. Clearly, i need to make sure that I get my samples to an appropriate temperature before checking gravities in the future (I use a hydrometer, btw)...do you think the high temps of the samples would be enough to skew my readings this much?

The mash temps I used were taken from an article I read on ideal temp ranges for step mashing (this was my first attempt at a step mash).

https://byo.com/mead/item/1497-the-science-of-step-mashing

Do you have any recommendations for more reading on the subject so that I can familiarize myself further with ideal temp ranges?

As for the quality of the grains, I'm not at all an expert on the subject...but I've done a couple of brews with products from this local brew supply store (granted they were not step mashes) with results close to what I was looking for (most recent one actually overshot the target OG by a few points).

Does my technique for sparging look sound to you? I basically copied what I have seen on a few youtube videos...keep the water at a certain level above the grain bed and collect the desired volume of wort.

Thanks again for your thoughts.

 

[Roland_deschain]

Did you use a hydrometer to check your pre boil? If so, did you adjust for the temperature of the sample?
A measured pre boil of 1.014 at 180 deg would adjust to 1.043 at 60 deg.

 

[geoffm33]

If all you used was 4 lbs of DME (which has a potential of about 44 pts/lb) you would have 176 gravity pts. In 5 gal of wort, the DME by itself would give you an SG of:

SG = 1 + (176 / 5) / 1000 = 1.035​

So, clearly your post-boil SG measurement has some serious error.

Assuming your 1.014 pre-boil SG was taken before you added any DME, that represents a conversion efficiency of 50% - 60%. This is very low, since conversion efficiencies of 95% or better are possible with optimal mash conditions. The largest contributor to low conversion efficiency is too coarse a crush, such that conversion cannot reach the centers of the grits during the allotted mash time. In your case your mash temps may have also been an issue. 145°F is on the low side, and both gelatinization and enzyme action will be significantly slower than at higher temps. Conversely 162°F is on the high side, and denaturing of enzymes will be fairly rapid. And, unless you have calibrated your thermometer, the measured temps could be significantly in error.

Brew on

In addition to this, the DME may not have been thoroughly mixed in giving you a lower reading.

 

[bbedell]

Did you use a hydrometer to check your pre boil? If so, did you adjust for the temperature of the sample?
A measured pre boil of 1.014 at 180 deg would adjust to 1.043 at 60 deg.

I did use a hydrometer...I'm guessing the sample was around 160-170 at the time it was measured as I was sparging @ 170 degrees. I did not adjust for temperature, and it looks like in the future I'll have to learn how to do this or simply wait until the sample cools to check a gravity.

I mixed the DME as thoroughly as possible after each addition, but there is always the chance of user error with a new brewer like myself

 

[xpops]

it looks like in the future I'll have to learn how to do this

Brewer's Friend has an excellent mobile app with a bunch of calculators in it. ABV calc, hydrometer temp adjust, priming sugar calc, brewhouse efficiency...the list goes on. Very handy to have through the entire beer making process!

 

[shoengine]

I did use a hydrometer...I'm guessing the sample was around 160-170 at the time it was measured as I was sparging @ 170 degrees. I did not adjust for temperature, and it looks like in the future I'll have to learn how to do this or simply wait until the sample cools to check a gravity.

I mixed the DME as thoroughly as possible after each addition, but there is always the chance of user error with a new brewer like myself

I did the same in my conversion failure a few weeks ago. Temps are extremely important for measuring everything. I've been making notes about this stuff so I don't forget it when I'm rushing around during a brew day.

 

[bbedell]

Thanks for all the great insight guys. Not to change the subject but for any of you with Helles experience: are you a fan of the 48 hour diacetyl rest after 14 days? Also, how close are you trying to get to your target final grav before racking to secondary? Thanks

 

[xpops]

I just brewed my first Lagers a few weeks back - a Helles along with a schwarzbier. I used brulosophers quick lager method, and after 2 weeks they taste excellent and going to start cold crashing tomorrow!

 

[bbedell]

Where can I find a rundown of this method?

 

[enkamania]

Where can I find a rundown of this method?

http://brulosophy.com/methods/lager-method/

 

[bbedell]

Thanks! Looks awesome. Any idea what he means by "when no diacetyl or acetaldehyde is detected"? How can we detect these? I'm assuming they're gone after a 48 hour rest as most recipes I've read recommend this time frame?

 

[xpops]

i strongly recommend you read through john palmer's How To Brew book - it's an excellent primer to anyone undertaking the art of homebrewing! great first place to start.

As for diacetyl, and acetaldehyde they can be described as "buttery" and "green apple" respectively. check out the common off flavours from How to Brew here.

cheers,