Temps drops during mash, is this a problem

[DonGavlar]

hi all,

For my last few batches I’ve been trying to dial in more on consistency and efficiency. One thing that really bugs me is I always drop around 4-5F during my hour mash.

I mash 5 gall batches in a 10 gal cylinder cooler, I cover the top of the grain with foil to limit heat loss to head space.

Say I start a mash at 154F, i usually am reading around 148/149F when the hours up. Its really bugging me as surely I’m ending up with wort with an unintended characteristic. Is this temp drop ok? Or am I going to have to buy a new, smaller cooler?

Thanks

 

[day_trippr]

4-5°F starts to get into the meaningful range with a shift away from dextrin production.
For some recipes that might matter, for others not so much.

How do you know that you didn't lose most of that 4-5°F at dough-in?
What is your mash process - do you preheat the tun or do you calculate a strike temperature that accounts for the tun's temperature and mass?

When I brewed with a 10g Rubbermade I used BeerSmith2's strike water calculator and it never failed to hit the target mash temperature within a degree F.
After that there was only a degree temperature loss through an hour of being left alone (ie: no opening the lid)...

Cheers!

 

[JONNYROTTEN]

I do 10 gallon batches and my numbers are usually exactly like yours. Sticklers might say it effects your beer. 5 years and endless batches later and those numbers make a mighty fine beer. Could there be a slight difference from beer to beer..maybe but I'm not mass marketing them so I'm ok with it.

 

[JohnSand]

I'm with Johnny. If it really bothers you, add some hot water. But I shoot for about 152 every time. If mashing outside in cold weather, I try to start at 156. I don't care if it cools to 149.

 

[Bklmt2000]

hi all,

For my last few batches I’ve been trying to dial in more on consistency and efficiency. One thing that really bugs me is I always drop around 4-5F during my hour mash.

I mash 5 gall batches in a 10 gal cylinder cooler, I cover the top of the grain with foil to limit heat loss to head space.

Say I start a mash at 154F, i usually am reading around 148/149F when the hours up. Its really bugging me as surely I’m ending up with wort with an unintended characteristic. Is this temp drop ok? Or am I going to have to buy a new, smaller cooler?

Thanks

Any effect on the resulting beer is minimal at most. IMO, nothing to worry about.

Most of the starch conversion happens in the first 20-ish minutes of the mash; after that, not a big deal.

 

[DonGavlar]

4-5°F starts to get into the meaningful range with a shift away from dextrin production.
For some recipes that might matter, for others not so much.

How do you know that you didn't lose most of that 4-5°F at dough-in?
What is your mash process - do you preheat the tun or do you calculate a strike temperature that accounts for the tun's temperature and mass?

When I brewed with a 10g Rubbermade I used BeerSmith2's strike water calculator and it never failed to hit the target mash temperature within a degree F.
After that there was only a degree temperature loss through an hour of being left alone (ie: no opening the lid)...

Cheers!

I’ve always used beersmith to calculate my strike temp and pre-heat my tun for around 10-20 mins before dough in. At this point I’ve dialed it down to hit my target pretty much dead on every time. I always stir thoroughly for 3-4 minutes to look for any dough balls, this time also allows the temp to settle. I then take a reading and Im pretty much always dead on target.

But after the 60-90 mins im usually down a minimum of 5F. The only reason its started bothering me is I often get an FG a little lower than anticipated and I wondered wether it was due to half of my mash time actually being lower than what I’ve put into beersmith.

I do open the lid at the 10 min mark to take a pH reading and again at 30/40 mins just to quickly take a temp reading to check it hasnt gone too low.

 

[Jtk78]

So you're opening the cooler twice, once for PH and once to check temp. Can you use the valve to take the sample? This is where I get my PH sample. I bet if you didn't open the cooler at all, you'd find you only lose half of what you have been.

 

[DonGavlar]

So you're opening the cooler twice, once for PH and once to check temp. Can you use the valve to take the sample? This is where I get my PH sample. I bet if you didn't open the cooler at all, you'd find you only lose half of what you have been.

I can do yes, but ive heard that taking a reading from the valve isnt always accurate as the mash should be mixed first, the runnings from beneath the false bottom may be less diluted than the top for example. That may have been just a myth though.
With temp reading, i guess I could take it from the valve yeah but wouldnt its temp drop when a small volume is put into a room tempture glass. May be over thinking it but just want to make sure im being accurate.
Perhaps ill give it a go next time and see if it helps, aslong as the ph is still acurate taking from the bottom.

Thanks

 

[Jtk78]

I can do yes, but ive heard that taking a reading from the valve isnt always accurate as the mash should be mixed first, the runnings from beneath the false bottom may be less diluted than the top for example. That may have been just a myth though.
With temp reading, i guess I could take it from the valve yeah but wouldnt its temp drop when a small volume is put into a room tempture glass. May be over thinking it but just want to make sure im being accurate.
Perhaps ill give it a go next time and see if it helps, aslong as the ph is still acurate taking from the bottom.

Thanks

I don't use a traditional false bottom, I use a mesh cooler bag from @wilserbrewer I'll be interested to hear others opinions on taking the PH sample from the valve.

In regards to the temp reading at 30 minutes in, are you doing anything to adjust the temp at that time or just taking the reading? How many degrees are you losing over the first 30 minutes compared to the end of the mash? I would try to just leave it closed and see what you lose without opening it .

 

[DonGavlar]

I don't use a traditional false bottom, I use a mesh cooler bag from @wilserbrewer I'll be interested to hear others opinions on taking the PH sample from the valve.

In regards to the temp reading at 30 minutes in, are you doing anything to adjust the temp at that time or just taking the reading? How many degrees are you losing over the first 30 minutes compared to the end of the mash? I would try to just leave it closed and see what you lose without opening it .

Yeah, I think next brew I'll do this, just leave it be until times up and see where I end up. Usually at about the 30/40 minute mark I'm like 2/3F down if i remember correctly. A recent brew I did recently was meant to be a very malty full bodied beer, at the 40 min mark it had actually dropped from 155 to 149.8 or something, so in a panic I boiled the kettle and added some boiling water and stirred which bought it back up to about 153 which I then left until the end. By the end it was back down to 150F.

 

[Bklmt2000]

Don, I used to mash in a 10-gal Rubbermaid cooler, and to minimize heat loss, I used to cover the cooler lid during the mash with 2-3 old beach towels. The inside of those lids are usually hollow, so that's one avenue of heat loss.

Another thing I did was apply a layer of adhesive weatherstrip to the bottom rim of the cooler lid, so that when it was screwed onto the cooler and tightened down, that gap was completely filled. As a result, there was virtually no heat loss from where the cooler lid and body met.

 

[Smellyglove]

Why hasn't anyone yet said that insulation of the tun will help a lot, if one is worried about dropping temps during mash? It does

If TS is worried about losing temps, and is asking about if he needs to get a smaller MT, then I'd say just insulate the one he has.

 

[mredge73]

It matters if you want a German style beer that finishes high and sweet with a "heavy body".
At 148F you are converting more efficiently and will thin out the "body".
The long chain sugars that contribute to this "body" will continue to break down as long as the enzymes are active.

20 minutes is really all you need to convert everything that you want.
If you are having trouble holding temp and don't want to invest in more equipment, just mash out early.
To deactivate the enzymes heat to 170ish; this should stop any further conversion.

If you want a thin body lawnmower style summer beer, 148F for 60+ minutes is a great target. Otherwise, 156F for 20-30 minutes should be a good target for these malty brews.

 

[Shwagger]

Drill some holes in the top of the lid and fill it with expanding foam. Helps a lot. Mine will stay dead on. Also use a wired thermometer that will allow the lid to close over the wire. Less opening.

 

[DonGavlar]

Thanks all for the suggestions. Will take them all into account.

My take homes are to just leave it be with the lid on for the entire mash and get it more insulated. will get it done.

As for whether its ok or not to just take the pH sample from the valve without stirring, I'll have to do some further digging.

Thanks.

 

[Jtk78]

.........

As for whether its ok or not to just take the pH sample from the valve without stirring, I'll have to do some further digging.

Thanks.

Please report back with your findings.

 

[DonGavlar]

Please report back with your findings.

I've decided, instead of asking around, on my next brew I'm going to do my own mini experiment.
First I'm going to dough in and stir thoroughly. I'll seal the lid and let it sit for 10 mins. Then, without removing the lid, I will draw a sample out of the valve into one container and then I will open the lid and give the mash a good stir and then draw a second sample into another container. I'll take a pH reading of both samples and report back to you here with the results.

I know for the sake of my temp problem this isn't helping, however, if it turns out stirring the mash up before a pH sample has no affect on pH then I have no other reason to remove the lid, meaning I can leave my lid on for the full mash with out any issues.

Cheers.

 

[Kent88]

See mash time links in my sig.

Maybe check the temp at the half hour mark, and add some boiling water?

These calculators are kind of helpful.

 

[DonGavlar]

See mash time links in my sig.

Maybe check the temp at the half hour mark, and add some boiling water?

These calculators are kind of helpful.

Thanks, I just plated up some homemade curry and cracked open a bottle of homebrew so this'll make some good listening while I enjoy.

Cheers.

 

[wilserbrewer]

Couple points....

Be sure to stir the grains in well, then pause for a few minutes and stir really well again then take a temp.

I have observed that if the mash temp is taken to soon, a false high reading will result as the grain and water has not reached a true equilibrium.

As for losing temp, if it bugs you so much just mash in a couple degrees high and anticipate the drop, especially if your trying to mash high and produce a malty beer.

Say for your beee that you wanted to mash at 154, let it start at 156-157 and welcome the drop, it’s really not that big a deal, just work with the system you have rather than worry about it.

Brulosepher did an exbeeramint where the same beer was mashed at 148 and again at 158, there was a difference in FG, yet lots of experienced tasters couldn’t tell the two apart ... go figure stop worrying

 

[VTX1300]

I was loosing 5 to 6 degrees over the hour in my 10 gallon round MT until I cut a piece of 3\4 inch thick rigid foam insulation and covered it in aluminum foil to close off the extra head space. I have it cut to fit fairly snug after wrapped with foil. Then slide it all the way in till it sits on the mash. Now I only loose 1degree over the hour. It's easy to make and works well. I used an eye bolt and a fender washer as a handle so i can get it back out.

 

[FunkedOut]

I did the same experiment as you plan, with drawing a valve sample for ph, then stir and sample off the top.
I measured the same ph, so I now leave it sealed and draw a sample from the valve. I’m curious to read your results.
I’m a bagger with no false bottom FWIW. Bag is laying right on dip tube.

Regarding the temp drop, i’m Getting about a 6*F drop on a 90 min mash using two layers of reflectix and a moving blanket. I overshoot the strike temp by 5*F or so. Gives me plenty of time to wrap the reflectix and put the lid on.
Several minutes later, the water cools down and the reflectix warms up, so it holds heat better. Maybe you can use this method to preheat your tun to save a little time and water.

Regarding FG, I always record strike temp, temp when finished doughing in and temp when mash is done. I always hit the mash temp after dough in to within -1*F, +0*F, based on beersmith calcs. Depends on how long it takes me to dough in, dough balls, etc.
I found that for every mash I’ve ever done, even when my temp drop was greater, the FG would match what Beersmith calculates if the mash temp used in BS was the midpoint between actual mash start and end. This held true for 60min or 90min mash.
So now, a 90min mash, I plan on a 6*F drop and shoot for a mash start temp that is 3*F higher than the BS mash temp target.

Works so well, I’m having a hard time justifying complicating things with a RIMS.

 

[Horseflesh]

Most of the starch conversion happens in the first 20-ish minutes of the mash; after that, not a big deal.

Conversion can happen that fast but it depends on the crush, etc. You can't know for sure how long it takes in your system until you do tests.

I always assumed I was getting full conversion promptly as the common wisdom dictates... Turns out it takes me 90 minutes!

 

[wilserbrewer]

Works so well, I’m having a hard time justifying complicating things with a RIMS.

I like and agree your simple approach to temperature management. Compensating for mash temp loss by raising temps by a few degrees works well and is very easy.

 

[applescrap]

Imo in a well done blind triangle taste test, it will likely be not possible to tell the difference between 148 and 160. Probably more. Perception bias is strong and people will judge as they see it, but imo the above remains the facts.

Im going to edit here. If you perceive one temp better than another than that absolutely has value too! There is nothing wrong imo, with feeling a strong preference for something, wether measureable or not.

 

[FunkedOut]

http://brulosophy.com/2015/10/12/the-mash-high-vs-low-temperature-exbeeriment-results/

 

[smyrnaquince]

I was loosing 5 to 6 degrees over the hour in my 10 gallon round MT until I cut a piece of 3\4 inch thick rigid foam insulation and covered it in aluminum foil to close off the extra head space. I have it cut to fit fairly snug after wrapped with foil. Then slide it all the way in till it sits on the mash. Now I only loose 1degree over the hour. It's easy to make and works well. I used an eye bolt and a fender washer as a handle so i can get it back out.

This worked for me, as well.

 

[applescrap]

^^pic? I am having trouble picturing this