Mash Temperature - Effects & Control

[tfxm]

hey y'all.

i wanted to ask a question in the hope to clarify my idea of mash temperatures and its effects.
i fairly new to all grain, so forgive any ignorance ....

i understand that higher mash temps produce more unfermentable sugars, but does it also affect the gravity of the wort? so basically, assuming mash temp is the only variable, if i mash at 70 degC will i produce a wort higher in gravity than if i mashed at 60 degC? or would i simply get the same gravity readings, but a lower attenuation?

also, im getting fairly significant temp differences from different parts of my mash at mash-in. is stirring the mash to help obtain a uniform temperature a bad move? or is there a better way to maintain temp across the mash? how do people with a welded thermostat know their reading is correct across the mash? or, maybe, im just over-thinking things and i should have another ipa and move on ......

my ag details: i mash in my brew kettle on my stove - a fairly heavy stainless steel pot which retains heat really well (actually a PITA when i come to chilling in the sink .... ). small batches, really small .... around 4.5L into the fermenter. brew small, brew often ....

cheers,
tom

ps. hooray for sierra nevada back in stock around melbourne ... 'tis like californian gold!

 

[mika]

Higher mash temps result in the same SG of the wort (that's only affected by efficiency of your system) just less attenuation, given the same yeast profile. Also the amount of complex sugars you add to the mash (crystal malts) affects the attenuation.

Mash temp really doesn't matter, what matters is the mash temp for your system. Variances will always exist within the mash, unless constant stirring and then you're going to lose more temperature over the duration of the mash. Measure the mash in the one spot, the same spot every time and calibrate your mash temps to the FG you desire. It takes a while to dial in your mash system, but with 4.5L batches, I think you can afford to do that.

 

[Ducatiboy stu]

I always give the mash a stir every 15mins, and I have noticed that the mash temp does vary thru the mash..thats why i stir. But it isnt critical....I just like doing it... B)

 

[kabooby]

I think it is very important to have a uniform temperature through the mash. You dont want to have hot and cold pockets otherwise you will get different results everytime you mash. Stiring helps this. Underletting also helps as the water raises into the grain bed and the grain soaks in evenly.

Kabooby

 

[tfxm]

hey, thanks for the replies!

mika, thanks for clearing up the science-side for me.

i would assume a uniform temperature would be important, but i can also understand that, if you have your mash system dialed in, you can compensate for discrepancies ...

i like stirring too! ha ... are there negatives to stirring?
anyone know how commercial micro's maintain mash temps?

 

[Ross]

Not sure what water to grain ratio you are using, but if you have big temp differences I'm assuming it's fairly thick.
Try 3L to 1kilo of grain. The looser mash will help considerably in getting an even mash temp.

cheers Ross

 

[shonky]

When stirring it is important not to do it too vigorously (ie try not to create a vortex as you are stirring), this promotes the formation of Beta-glucans that can cause your mash to stick and also cause other staling problems down the track. Also try and minimise oxygenation of the mash as this can also cause staling effects.

A gentle stir from time to time seems to be the way to go.

Cheers

 

[lagers44]

Instead of stirring you can try to recirculate the mash liquid either by hand or pump , this will help even out the temperature as well.

Lagers

 

[Thirsty Boy]

I stir pretty thoroughly when I mash in to get a nice even temperature throughout the mash-tun, but then I don't bother with stirring for the rest of the mash.

I cant think of any particular disadvantage of stirring (aside from it increasing temperature loss) and lot of commercial breweries both large and small stir constantly throughout the entire mash - it helps with getting a full conversion quickly and of course matters a lot if you are step mashing via direct heat.

Don't think it would make a hell of a lot of difference on a homebrew scale though.

Lts of different ways to mash, most of them work. Try a few out and just stick with the one that feels right to you and that you think you can do consistently and repeatably.

Thirsty

 

[BenH]

I stir my mash every 15 mins or so to try to maintain an even temperature throughout, then check temperature - and apply some direct heat if required to bring back up to target temp (while stirring to avoid scorching).

I generally only have to reheat once during a 75 minute mash.

 

[bugwan]

For what it's worth, I underlet (using gravity feed from a HLT above the Mash Tun (esky)) then stir well, running a thermometer up and down the mash to make sure I've got a pretty steady temp from one end to the other. Stirring up the cooler bits helps balance the temps. My water to grist ratio varies by recipe, but for a single infusion, batch sparge it usually runs at about 2.5:1.

 

[tfxm]

Thanks for all your help & suggestions, guys.
Will try some of them during today's brew session ..... A pliny clone ....

Cheers,
Tom

 

[yardy]

For what it's worth, I underlet (using gravity feed from a HLT above the Mash Tun (esky))

slightly ot, when underletting do you add the entire grain bill at once or is it gradual as the water level increases ?

cheers
yard

 

[matti]

slightly ot, when underletting do you add the entire grain bill at once or is it gradual as the water level increases ?

I am by no means a practical expert in ag but of what has bees said in various threads is.
When batch sparging underletting is the best way to infuse a mash.
When I brewed with Pumpy we added all the grain then we underlet the brew liqour.

So yes would be the answer.

You can do it opposite by gradually enter the grain into to preheated water and stir at beginning middle and at end of it too.

 

[yardy]

cheers matti,
might have to look at rebuilding the brewstand and let gravity do it's thang.

cheers
yard

 

[dig]

anyone know how commercial micro's maintain mash temps?

Stirring. Mind you, the bigger the mash, the less trouble you're going to have with temperature loss (surface area: volume ratio). Stepped mashes in steam jacketed mashing vessels (eg Malt Shovel) will stir continuously whereas static isothemal mashes (such as LC) don't stir at all. Lots of different ways to mash.

 

[tfxm]

I just wanted to thank people again for their replies on this thread.

I just took a gravity reading of an ale brewed a week ago using suggestions posted here, and its down to 1.010. MUCH lower than i have previously been experiencing ... awesome. Occasional stirring and upping the water-grain ratio seems to have done the trick.

Cheers All!
Tom