Low Gravity and ABV

[jfwayBrews]

Been doing the BIAB for a few years now, but just kind of winged it making up recipes and not really calculating target numbers and so on.
Last several batches, I’ve been using www.brewersfriend.com to calculate my target OG and FG. Every batch I’ve done doing this my numbers are much lower.
I’m still making great beers but got me thinking what I’m doing wrong.

For example, last completed batch I did was 12.5# 2-Row, 1# Cara 20, and .5# Dextrose corn sugar. Calculation was target OG 1.072 and FG 1.017 for 7.2% ABV.
Using a hydrometer, I ended up with OG 1.050, FG 1.002 for 6.3% ABV.
I’ve tested the hydrometer with distilled water and it’s off by 4 points, so I’ve adjusted both readings for that.
I just bought a Brix reader, and batch that is fermenting now was a target OG of 1.060, but I got 1.050 (12.5 brix).

Here is my process. Heat 7.5 gallons to 164 degrees. Drop in all my grains in the bag and stir to get the clumps out. Steep for 60 minutes.
I’ll stir 1-2 more times. This usually ends the temp at 152 after the 60 min. Occasionally, I’ll need to heat on low for 5 minutes to get the heat back up.

After the mash, I squeeze/drain the bag and am left with about 6.2 gallons to boil and add the hops.
Ending wort is always right around 5 gallons.

I’ve never complained about this because for years, my beers have always been right on for taste and the right amount of alcohol, but now that I’m tracking numbers, wondered if my batches could be more efficient.

Any advice would be appreciated.

 

[lumpher]

My first thought is the efficiency difference is caused by BIAB/No Sparge vs Recirc/Sparge calculations. If so, the answer would be to either keep doing what you're doing and go with lower ABV or increase the grains to make up the difference in efficiency.

 

[RM-MN]

Who mills your grains? Often an OG well below what is calculated is due to low efficiency from grains milled too coarsely.

 

[DuncB]

It's most likely the usual interaction of factors of crush size, pH and salts with the target temperature of your mash (use a strike water calculator ) and then sparge or no sparge.

@doug293cz has an excellent spreadsheet that helps shows extraction, mash volume with and without sparge effects as well.

So do look ( measure) at post mash gravity, pH but most importantly you should be a really fine crush with a BIAB approach.

Do ensure that all liquids are well mixed before sampling, are temperature corrected as well.

Strike water temp calculator suggests dough in at 158 for a 152 mash temp with grains at 65 F.

You are a bit hotter than this so might be shortening some enzymes life span the strike calculator says mash temp would be 158 which is 70C this is on the high end and although it's falling the damage may well be done before reaching that temp.

BIAB experts may well correct my assumptions.

 

[doug293cz]

For example, last completed batch I did was 12.5# 2-Row, 1# Cara 20, and .5# Dextrose corn sugar. Calculation was target OG 1.072 and FG 1.017 for 7.2% ABV.
Using a hydrometer, I ended up with OG 1.050, FG 1.002 for 6.3% ABV.
I’ve tested the hydrometer with distilled water and it’s off by 4 points, so I’ve adjusted both readings for that.
...

Here is my process. Heat 7.5 gallons to 164 degrees. Drop in all my grains in the bag and stir to get the clumps out. Steep for 60 minutes.
I’ll stir 1-2 more times. This usually ends the temp at 152 after the 60 min. Occasionally, I’ll need to heat on low for 5 minutes to get the heat back up.

After the mash, I squeeze/drain the bag and am left with about 6.2 gallons to boil and add the hops.
Ending wort is always right around 5 gallons.

For 13.5 lb of grain, 7.5 gal strike, 6.2 gal pre-boil, and 5.0 gal post boil, and assuming you added the dextrose to the boil kettle (not in the mash), I get your lauter efficiency at 74.8% and your target OG @ 100% conversion efficiency as 1.080.

If I use "Goal Seek" in my spreadsheet to adjust the conversion efficiency to get your OG of 1.050, conversion efficiency comes out at ~56%, which is pretty dismal.

This means that your low OG is entirely due to what (didn't) happened in the mash, and not that you didn't sparge.

To increase your conversion efficiency you should (in decreasing order of importance):

1. Crush your grain finer
2. Mash longer
3. Use lower strike water temp to get a mash starting temp under 156°F
4. Insure your mash pH is between about 5.3 and 5.6

You can insure your mash is done by monitoring the SG during the mash every 10 - 15 minutes after about 45 - 60 minutes (easy to do since you have a refractometer, just stir well before taking the samples), and mashing until SG stops increasing between successive samples.

Brew on

 

[DuncB]

@jfwayBrews Can't disagree with the concise way @doug293cz has summarised some tips.

Some water salts can also help the enzyme performance as well and or you might have terrible brewing water that you are starting with. But you do say the beer tastes alright so it's likable water!

 

[jfwayBrews]

Thanks for all the feedback.
Corn sugar always goes into the boil, not the mash. Only reason I add this is to get the ABV up. I like the beer from 5.5-6.5%. Past experience has taught me how much to add based on my grain amount, but if I can get the efficiency correct, I won’t need the sugar.
Grains are coming from MoreBeer.com and already milled. Not really sure what they should look like. Are freshly milled grains better? Meaning, is it worth buying a grinder and ordering un-milled grains and doing it myself right before the brew? Or just to ensure that they are finely milled?
Water should be fine. It’s well water that goes through a filter and we drink it every day. I have a neighborhood of guys that just happen to show up at my garage every Saturday after cutting the grass and have yet to turn down a third pint.

I’ve used Brew in a Bag (BIAB) Calculator ~ to calculate my strike water temp and volume but have noticed I have to add more water at the end to get to just over 6 gallons for pre boil.
Didn’t think extra water in the mash would matter. I had just assumed it was better to let more water steep in the grains for 60 min, rather than rinse another ½ gallon at the end.
If I use their starting temp, I have to get the propane going a few times as it will drop below 152. Might not happen as much now in the summer, but in fall/spring when I brew in MA, it happens often.
Hard to control with the propane. Temp drops to 150, I turn on low for a few minutes, then the next thing I know, the temp is reading 160+. I have a thermometer on the pot and have also tried the digital probe. Both seem to lag what might be really going on.
Or maybe, I’m just walking away from the pot for longer than I think.

I have a pump with a control flow where I can recirculate during the mash. What’s the thought on this? Recirculate for maybe the last 10-20 min of the mash with a low flow?

Great idea about mashing longer and just take readings every 10-15 min until the SG holds steady.

Here are my steps for next batch, feel free to agree or disagree.
Strike water to correct gallons and rinse until I get the needed starting pre wort amount
Strike temp 156 and hold a minimum of 152 (do a better job monitoring temp fluctuation).
At 45 min, recirculate on a low flow. Or should this be the whole mash time?
At 45 min, start taking gravity readings until I get to my target SG.

 

[kaffeenjunkie]

Double post

 

[kaffeenjunkie]

Almost 10 years of BIAB brewing and I faced the same issues at the beginning.

Once you begin to really pay attention to what your doing
strike temps and correct amount of water
Correct mash temps for the style your trying to achieve.
pH-very important- get a pH tester -not strips
correct amounts of salts
grain crush should be fine but not flour. My mill is set to credit card width.
evap rate during boil

You will find you hit numbers every time whether you do a one hour mash or an all night mash. Squeeze or no squeeze. The key is paying attention to the details. You can make beer with the casual approach but you will make better, even great, beer when you’re paying attention to details.

The machinations you were going to do for your next batch is unnecessary.
Put all your water into your pot, heat to proper temp, dough in. Check pH after 20 mins and adjust if needed. Very seldom do you need to adjust.
BIAB is supposed to be easier, not harder.

 

[Miraculix]

Been doing the BIAB for a few years now, but just kind of winged it making up recipes and not really calculating target numbers and so on.
Last several batches, I’ve been using www.brewersfriend.com to calculate my target OG and FG. Every batch I’ve done doing this my numbers are much lower.
I’m still making great beers but got me thinking what I’m doing wrong.

For example, last completed batch I did was 12.5# 2-Row, 1# Cara 20, and .5# Dextrose corn sugar. Calculation was target OG 1.072 and FG 1.017 for 7.2% ABV.
Using a hydrometer, I ended up with OG 1.050, FG 1.002 for 6.3% ABV.
I’ve tested the hydrometer with distilled water and it’s off by 4 points, so I’ve adjusted both readings for that.
I just bought a Brix reader, and batch that is fermenting now was a target OG of 1.060, but I got 1.050 (12.5 brix).

Here is my process. Heat 7.5 gallons to 164 degrees. Drop in all my grains in the bag and stir to get the clumps out. Steep for 60 minutes.
I’ll stir 1-2 more times. This usually ends the temp at 152 after the 60 min. Occasionally, I’ll need to heat on low for 5 minutes to get the heat back up.

After the mash, I squeeze/drain the bag and am left with about 6.2 gallons to boil and add the hops.
Ending wort is always right around 5 gallons.

I’ve never complained about this because for years, my beers have always been right on for taste and the right amount of alcohol, but now that I’m tracking numbers, wondered if my batches could be more efficient.

Any advice would be appreciated.

What's the efficiency that you type into the brewers friend calculator?

 

[jfwayBrews]

It defaults to 75% efficiency, so I leave it at that.

 

[terrypratt1]

Thanks for all the feedback.
Corn sugar always goes into the boil, not the mash. Only reason I add this is to get the ABV up. I like the beer from 5.5-6.5%. Past experience has taught me how much to add based on my grain amount, but if I can get the efficiency correct, I won’t need the sugar.
Grains are coming from MoreBeer.com and already milled. Not really sure what they should look like. Are freshly milled grains better? Meaning, is it worth buying a grinder and ordering un-milled grains and doing it myself right before the brew? Or just to ensure that they are finely milled?
Water should be fine. It’s well water that goes through a filter and we drink it every day. I have a neighborhood of guys that just happen to show up at my garage every Saturday after cutting the grass and have yet to turn down a third pint.

I’ve used Brew in a Bag (BIAB) Calculator ~ to calculate my strike water temp and volume but have noticed I have to add more water at the end to get to just over 6 gallons for pre boil.
Didn’t think extra water in the mash would matter. I had just assumed it was better to let more water steep in the grains for 60 min, rather than rinse another ½ gallon at the end.
If I use their starting temp, I have to get the propane going a few times as it will drop below 152. Might not happen as much now in the summer, but in fall/spring when I brew in MA, it happens often.
Hard to control with the propane. Temp drops to 150, I turn on low for a few minutes, then the next thing I know, the temp is reading 160+. I have a thermometer on the pot and have also tried the digital probe. Both seem to lag what might be really going on.
Or maybe, I’m just walking away from the pot for longer than I think.

I have a pump with a control flow where I can recirculate during the mash. What’s the thought on this? Recirculate for maybe the last 10-20 min of the mash with a low flow?

Great idea about mashing longer and just take readings every 10-15 min until the SG holds steady.

Here are my steps for next batch, feel free to agree or disagree.
Strike water to correct gallons and rinse until I get the needed starting pre wort amount
Strike temp 156 and hold a minimum of 152 (do a better job monitoring temp fluctuation).
At 45 min, recirculate on a low flow. Or should this be the whole mash time?
At 45 min, start taking gravity readings until I get to my target SG.

For what it's worth - the only online vendor I've found that offers a Double Crush is Atlantic Brew Supply (Welcome to Atlantic Brew Supply - Your friendly neighBREWhood store!). As I too do BIAB I wanted as fine a crush as possible so I have been buying my grains there specifically for the crush. I can say that visually the crush seems finer than previous purchases; and I am pretty much hitting my targets. either by crushing yourself or having a provider able to execute a fine crush may well be what you need.

Terry

 

[Miraculix]

It defaults to 75% efficiency, so I leave it at that.

That is your problem. Adjust it to your calculated efficiency from previous batches and you can easily predict the future outcome.

However, a factual efficiency below 80% is arguably worthy of some further engagement, if you biab. A fine crush will bump your efficiency reliably.

Once I've moved to Germany and had to leave my trustworthy maltmiller.co.uk as my chosen malt vendor, my efficiency went south significantly. I miss the double crush .

 

[DuncB]

Heating the water to strike temperature dough in and stir.
Insulate the pot all round and you shouldn't need to worry about those hot surges you are getting by turning the propane on.
Ask more beer to crush the grains for biab or double crush them.
Don't worry about the pump to recirculate that will just add to the cooling.
You'll see a leap in mash efficiency I'm sure.

 

[jfwayBrews]

Got this response about crushing the grains.
The warehouse is not able to double crush our grains. The Grain Mill at the warehouse is set to 0.067

 

[VikeMan]

Got this response about crushing the grains.
The warehouse is not able to double crush our grains. The Grain Mill at the warehouse is set to 0.067

0.067 inches? Is that a typo? That would be about 1.7 mm. I usually say that gap size doesn't necessarily tell the whole story, because mill design and speed can also be factors. But 1.7 mm is ridiculously wide for any mill.

 

[madscientist451]

I’ve never complained about this because for years, my beers have always been right on for taste and the right amount of alcohol, but now that I’m tracking numbers, wondered if my batches could be more efficient.

Any advice would be appreciated.

So many of the replies above mention adjusting your mash PH for as part of the routine for better efficiency.
However, if you want to keep things simple and get more bang for your bucks, I'd get your own mill first.
You can then buy grain in bulk, save some money there and run your grain trough twice and perhaps get better efficiency that way.
Having your own grain stash and a mill also gives you the freedom to brew what you feel like brewing without having to plan ahead and specifically order supplies for each batch.
My 2 cents: Keep things simple, you have a process and method that works for you, if you don't get your own mill, just add some more base malt to your existing recipes to get the gravity you are looking for and don't worry about efficiency.

 

[RM-MN]

However, if you want to keep things simple and get more bang for your bucks, I'd get your own mill first.
You can then buy grain in bulk, save some money there and run your grain trough twice and perhaps get better efficiency that way.
Having your own grain stash and a mill also gives you the freedom to brew what you feel like brewing without having to plan ahead and specifically order supplies for each batch.

With BIAB you can mill the grains very fine. A Corona style mill will do that. Being that they are so cheap, you can probably pay for one with only a single bag of uncrushed grain and make beer of the ABV and style you want. Look up how one homebrewer modified one for his purposes.

https://www.homebrewtalk.com/threads/my-ugly-junk-corona-mill-station.90849/

 

[camonick]

I agree with the above posts about crush. MoreBeer is a good company, but their “milled” grains suck for BIAB brewing. For the cost of about 3 batches of beer, you can get a good 2 roller mill like the Cereal Killer or a Corona mill for even less. You will see a huge improvement when you control the way your grain is crushed.

 

[DuncB]

Got this response about crushing the grains.
The warehouse is not able to double crush our grains. The Grain Mill at the warehouse is set to 0.067

I'd say let them know that you are going to change your supplier.

 

[jfwayBrews]

The consensus is to get a finer milled grain for BIAB.
One-time, MB.com forgot to mill the grains so I ended up using a handheld blender with the blade on the bottom. I thought I was chopping it too fine, but maybe this was best.
Next batch I’ll try the handheld and I’ve ordered a digital PH tester to test my starting water, and I’ll test 10 min into the mash.
If I get better results, I’ll look into the Corona or even a grain mill.

 

[doug293cz]

I’ve ordered a digital PH tester to test my starting water, and I’ll test 10 min into the mash.

Starting water pH is irrelevant. What is important is the alkalinity of the starting water, as this determines how much acid (either from the grain, or added separately) is needed to shift the mash pH into the desired range. The best way to adjust mash pH is to have a detailed water reports (giving alkalinity, and concentrations of Ca, Mg, Sulfate, Chloride [not Chlorine], Carbonate, and Bicarbonate) and then using brewing water software to determine ion additions and predict the mash ph. You then use the pH meter to verify the results of the prediction, and then use that information to inform any tweaks to what your water calculation software is telling you. Trying to adjust the mash pH mid mash is kind of like closing the barn doors after the horse has escaped.

In any case, crush and mash temp & time are something you should get worked out before getting too worried about pH.

Brew on

ps. If you can't get your needed water information from your water supplier, then you can get a test done by Ward labs.

 

[jfwayBrews]

Did a BIAB this weekend. Finely crushed the grains using an Oster kitchen thing…
Borderline flour looking with husks mixed in.
I followed the strike amount/temps exactly as Brew in a Bag (BIAB) Calculator ~ said.

Two things that were off. My target fermenter wort was 5 gallons but ended with 4.2 gallons.
I was late setting my last timer, so maybe over boiled by 10 minutes. I guess it’s possible to burn it off, but that seems like too much for that amount of time.
My target gravity was 1.066 and got 1.057. This is a lot closer than I’ve been getting. I calibrated my brix reader a few batches ago. I’ll check what the final ABV is. As long as I hit the target ABV, it’s all good.

One thing I found odd is that during the mash, I measured gravity after 60 minutes and got 1.074. I’m surprised the number came down because while boiling, I’m losing water.
Wouldn’t the gravity go up as you are burning off water?
Let off a little bit of 162-degree wort into a mug, let it sit for about 10 min, then did my reading. Could the wort have been to warm and affected my reading.
So now I’m wondering if I should have mashed longer to try and get that gravity higher before the boil and maybe then I could have hit the 1.066 target.
And if so, is there a formula to use that says if you want to end with this gravity, shoot for a starting gravity of this….

 

[CascadesBrewer]

I followed the strike amount/temps exactly as Brew in a Bag (BIAB) Calculator ~ said.

One thing to note is that with any calculator, you need to update default settings with your own measured values. I like that calculator for how easy it is, but feel like it could have some better default values. The Grain Absorption value of 0.045 Gallons/Pounds is about half of what I have measured even with squeezing. A value of 0.07 would work better for me. The boil off rate of 1.25 is about what I get with an aggressive boil on my propane burner, but is much less than I get when brewing on my kitchen stove (around 0.7).

It is very helpful to take careful measurements for a batch or two to determine your actual values. For that calculator that would be Trub (the amount you leave behind in your kettle or are absorbed by hops), Boil off Rate, and Grain Absorption.

 

[DBhomebrew]

And if so, is there a formula to use that says if you want to end with this gravity, shoot for a starting gravity of this….

Pre-boil gravity (1.xxx) * volume = post-boil gravity * volume

Assuming very careful measurements of both gravity and volumes along with proper adjustments for temperature.

 

[VikeMan]

Pre-boil gravity (1.xxx) * volume = post-boil gravity * volume

I know what you mean to say here, but for the math to work, the gravity needs to be converted to "points per gallon" (or an equivalent scaled number). IOW, we need to take the "water reference" out. The easy way would be to subtract 1 from each gravity number.

(Preboil gravity - 1) * Preboil volume = (Postboil gravity - 1) * Postboil volume

 

[doug293cz]

Did a BIAB this weekend. Finely crushed the grains using an Oster kitchen thing…
Borderline flour looking with husks mixed in.
I followed the strike amount/temps exactly as Brew in a Bag (BIAB) Calculator ~ said.

Two things that were off. My target fermenter wort was 5 gallons but ended with 4.2 gallons.
I was late setting my last timer, so maybe over boiled by 10 minutes. I guess it’s possible to burn it off, but that seems like too much for that amount of time.
My target gravity was 1.066 and got 1.057. This is a lot closer than I’ve been getting. I calibrated my brix reader a few batches ago. I’ll check what the final ABV is. As long as I hit the target ABV, it’s all good.

One thing I found odd is that during the mash, I measured gravity after 60 minutes and got 1.074. I’m surprised the number came down because while boiling, I’m losing water.
Wouldn’t the gravity go up as you are burning off water?
Let off a little bit of 162-degree wort into a mug, let it sit for about 10 min, then did my reading. Could the wort have been to warm and affected my reading.
So now I’m wondering if I should have mashed longer to try and get that gravity higher before the boil and maybe then I could have hit the 1.066 target.
And if so, is there a formula to use that says if you want to end with this gravity, shoot for a starting gravity of this….

It appears you are having measurement errors somewhere. You are correct that SG increases during boiling as water evaporates, so it is not actually possible for your post-boil SG (OG) to be less than your pre-boil (end of mash) SG.

Letting your hot mash wort sample sit in an open cup can allow a significant amount of water to evaporate, which will give you an erroneously high SG measurement. It's better to take a sample with an eyedropper or syringe, which will minimize evaporation while the sample cools.

Also, before taking any mash or pre-boil SG samples, you need to insure the wort is fully homogenized to prevent false readings. This can be done with aggressive stirring, or recirculation during the mash (although AOI systems with malt pipes have their own challenges w.r.t. homogenizing all of the liquid in the system.) If you sparge, you also need to homogenize all of the wort before taking samples. Post-boil, things are already well homogenized due the the currents during boiling.

Brew on

 

[Bobby_M]

Thanks for all the feedback.
Corn sugar always goes into the boil, not the mash. Only reason I add this is to get the ABV up. I like the beer from 5.5-6.5%. Past experience has taught me how much to add based on my grain amount, but if I can get the efficiency correct, I won’t need the sugar.

You're going about efficiency all wrong. Efficiency is what your system and process delivers to you. If that doesn't match the OG that you wanted (too low), you accept the efficiency numbers you've been recording and SCALE your future batches to match reality. In other words, change the efficiency setting in Brewer's Friend to match your efficiency numbers. It will then tell you to use more grain. Boom, now you hit "your numbers".

Grains are coming from MoreBeer.com and already milled. Not really sure what they should look like. Are freshly milled grains better? Meaning, is it worth buying a grinder and ordering un-milled grains and doing it myself right before the brew? Or just to ensure that they are finely milled?

I think Morebeer threatens the grain with milling and just hope that the grain cracks under the fear. In other words, their crushed grain doesn't look crushed AT ALL. I run my shop mill at two gap settings. BIAB is gapped to .020" and Normal is gapped at .030".

Water should be fine. It’s well water that goes through a filter and we drink it every day. I have a neighborhood of guys that just happen to show up at my garage every Saturday after cutting the grass and have yet to turn down a third pint.

None of that suggests that it's suitable to brew with at all, nevermind if it was usable for even one extreme beer style vs. the other. No water is inherently suitable for both very light beers and very dark beers simultaneously with regard to mash pH.

I’ve used Brew in a Bag (BIAB) Calculator ~ to calculate my strike water temp and volume but have noticed I have to add more water at the end to get to just over 6 gallons for pre boil. Didn’t think extra water in the mash would matter. I had just assumed it was better to let more water steep in the grains for 60 min, rather than rinse another ½ gallon at the end.

Yes, it changes your efficiency. You should start with the entire water amount you need to end up with about 5.5 gallons into the fermenter. Try starting with 8.5 gallons in the mash.

If I use their starting temp, I have to get the propane going a few times as it will drop below 152. Might not happen as much now in the summer, but in fall/spring when I brew in MA, it happens often.
Hard to control with the propane. Temp drops to 150, I turn on low for a few minutes, then the next thing I know, the temp is reading 160+. I have a thermometer on the pot and have also tried the digital probe. Both seem to lag what might be really going on.
Or maybe, I’m just walking away from the pot for longer than I think.

Inconsistent mash temps will lead to inconsistent wort fermentability. Sometimes you'll have FGs of 1.004 and other times 1.024. This is why electric all in one systems have gotten so popular. Relatively hands off temp stability.

I have a pump with a control flow where I can recirculate during the mash. What’s the thought on this? Recirculate for maybe the last 10-20 min of the mash with a low flow?

I would not recirculate a mash that is not actively being temp controlled (electric). It just causes heat loss with very little benefit. If I were you I'd insulate the heck out of the mash while it's resting and try to avoid the temp rollercoaster as much as you can.

 

[jfwayBrews]

Like most things in my life, I feel I’m over complicating this. In the end, my beer tastes great, so why am I so concerned about achieving numbers and efficiency? It’s just the way I’m wired.
Everything was going fine until I started playing with these online calculators.

I agree with you Bobby_M. Brew your recipe and then adjust the next batch accordingly. Keep it simple.
BTW, just tapped one of these batches where I stated my numbers were off and it’s fantastic.

Next project is insulating the pot for mashing. I have a bunch of left over Reflective Roll Insulation that would work nicely.

 

[RM-MN]

Like most things in my life, I feel I’m over complicating this. In the end, my beer tastes great, so why am I so concerned about achieving numbers and efficiency? It’s just the way I’m wired.
Everything was going fine until I started playing with these online calculators.

I agree with you Bobby_M. Brew your recipe and then adjust the next batch accordingly. Keep it simple.
BTW, just tapped one of these batches where I stated my numbers were off and it’s fantastic.

Next project is insulating the pot for mashing. I have a bunch of left over Reflective Roll Insulation that would work nicely.

Before you go to the bother of insulating your mash pot, find out how long it takes to get full conversion using either iodine on the grains or your refractometer sample from the wort. You may be surprised to find that conversion is done much more quickly than you think and that insulating your mash pot would be a waste of time and material. Once conversion is complete, the temperature doesn't much matter as you can extract color and flavor over a wide range of temperature.

 

[Hoochin'Fool]

You may be surprised to find that conversion is done much more quickly than you think

So if I mashed in a little high and it took 10 minutes to get temp down from 156F to desired 152F, is my beer (fermenting as I type this) doomed to finish with a little higher final gravity? Mashed for a full hour, with final temp dropping down to 149F.

 

[BrewZer]

You can insure your mash is done by monitoring the SG during the mash every 10 - 15 minutes after about 45 - 60 minutes (easy to do since you have a refractometer, just stir well before taking the samples), and mashing until SG stops increasing between successive samples.

A drop of iodine will also tell you when you're getting close to full conversion -- put a small sample of wort on a white plate and put a drop of iodine in it. Any purple and you've still got starch in your wort. No color change -- you're done.

 

[doug293cz]

A drop of iodine will also tell you when you're getting close to full conversion -- put a small sample of wort on a white plate and put a drop of iodine in it. Any purple and you've still got starch in your wort. No color change -- you're done.

You really need to include some grain bits in the sample, as that is where any remaining un-gelatinized starch will be. You cannot reach 100% conversion if you don't first achieve 100% gelatinization. If you don't sample the grain, as well as the wort, you won't know if you have remaining un-gelatinized starch.

Many brewers don't like to include grain in their iodine test sample, as they never seem to get starch free result if they include grain. But if including grain gives you a positive test for starch, then your mash isn't done converting, even if a grain free sample tests negative for starch. This is why I never recommend the starch test, and always recommend monitoring the SG. If you like the starch test, then go ahead and do it.



Brew on

 

[RM-MN]

So if I mashed in a little high and it took 10 minutes to get temp down from 156F to desired 152F, is my beer (fermenting as I type this) doomed to finish with a little higher final gravity? Mashed for a full hour, with final temp dropping down to 149F.

I'd have to say, it depends. Mostly it depends on how fine the milling was. If it was a normal or slightly coarse it takes more time for the grain to fully gelatinize the starch and until that happens the enzymes are not greatly affected. However, a very finely ground grain will convert in (would you believe it?) less than 2 minutes.

Someday you need to blow your paycheck on a bottle of Povidone Iodine (less than $10 at major retailers, higher at a pharmacy) so you can check the grain particles for any leftover starches. Until you do that test repeatedly over a period of time you really are just driving blind. My intention when I started that experiment was to take a sample at 5 minutes from dough-in and test it, then every 5 minutes until the iodine no longer turned blue. Hmm, it didn't turn blue at the first sample so I repeated it on the next batch starting at 1 minute after dough-in and repeating the test every minute until conversion was complete.

I've seen it reported that sometimes there is never full conversion even after an hour. YMMV

 

[Hoochin'Fool]

I'd have to say, it depends. Mostly it depends on how fine the milling was. If it was a normal or slightly coarse it takes more time for the grain to fully gelatinize the starch and until that happens the enzymes are not greatly affected. However, a very finely ground grain will convert in (would you believe it?) less than 2 minutes.

Not sure how I'd describe my grain crush, other than "smallest gap possible on my cereal killer". It's definitely pretty fine, and I'm mashing full volume in a bag, so it's usually a fairly thin mash (if I'm going imperial, that's when the DME gets used)... I'm going to assume this beer will end up finishing a little higher than intended.

Someday you need to blow your paycheck on a bottle of Povidone Iodine (less than $10 at major retailers, higher at a pharmacy) so you can check the grain particles for any leftover starches. Until you do that test repeatedly over a period of time you really are just driving blind. My intention when I started that experiment was to take a sample at 5 minutes from dough-in and test it, then every 5 minutes until the iodine no longer turned blue. Hmm, it didn't turn blue at the first sample so I repeated it on the next batch starting at 1 minute after dough-in and repeating the test every minute until conversion was complete.

Isn't an iodine test only going to tell me that "you don't need to mash any longer", and nothing about how fermentable the wort is? And if all I care about is the "is the mash done" part, my refractometer could be telling me that equally well, no? (geez, like a guy can just spare $10 all willy-nilly )

 

[VikeMan]

Isn't an iodine test only going to tell me that "you don't need to mash any longer", and nothing about how fermentable the wort is?

The first part is correct if you define "don't need to mash an longer" as the point when there are no longer any starches. The second part is correct regardless.

 

[Hoochin'Fool]

The first part is correct if you define "don't need to mash an longer" as the point when there are no longer any starches. The second part is correct regardless.

I think what I'm hearing is "just because all the starch is gone doesn't mean the mash is done"... Can you explain it like I'm old?

 

[VikeMan]

I think what I'm hearing is "just because all the starch is gone doesn't mean the mash is done"... Can you explain it like I'm old?

Depends on your definition of "done." If done means "full conversion," i.e. all starch converted to something other than starch, then an iodine test can tell you that it's done. If done means the desired sugar/dextrin profile (IOW fermentability) has been reached, iodine is of less utility there. In this latter case, iodine can tell you that you are definitely not done or that you are possibly done.

 

[Hoochin'Fool]

Thanks Vikeman, I'm guessing if there was an inexpensive but accurate (and quick) way to determine sugar/dextrin makeup, then that's what everyone would be doing, instead of just waiting the usual 60 minutes for mash to "finish".

 

[VikeMan]

Thanks Vikeman, I'm guessing if there was an inexpensive but accurate (and quick) way to determine sugar/dextrin makeup, then that's what everyone would be doing, instead of just waiting the usual 60 minutes for mash to "finish".

You are right... there are accurate ways to do a sugar profile assay, but none are inexpensive. I'm guessing even a nice used HPLC setup would run close to $100K. And I'm not sure how fast they are. For the rest of us, there's experience and software predictions.