Mash Temp. How low is too low?

[Geoff Bacon]

I did a brew last weekend, but had a few problems with my mash temp. I bought a cheap digital thermometer thinking I was getting a bargain. Turns out, you really do get what you pay for. Long story short, by the time I added my grain and figured out there was a problem with the thermometer, my actual temp was sitting at 60 deg C. My target temp was 66. It took me close to 45 min mash time to get up to temp. I left it sitting for additional 15-20 mins longer (75-80 min total time). In the end I actually exceeded my target gravity. My question is, how will this lower mash temp and longer time affect the final product? TIA. 

[Peter Smith]

In general it will produce a more fermentable wort as more complex starches will have been converted to easily fermented sugars, therefore it will finish fermenting at a lower gravity, taste dryer and have less body (feel a bit thiner) then if you say mashed at 67-68C. 

Will depend on your grain bill a bit as well, as I understand it crystals and carapils etc are not impacted by mash temps as starches are converted to sugar during their manufacturing and these sugars wont break down any further in the mash, stand to be corrected as to why this is or isnt....

[Grant R Baker]

Peter has answered most of it... most beers are mashed at 65-68C but once the enzymes are active they keep going even if the temp falls below 60C.

 

That said below 60C and other things can grow too. So keep the mash at 65C and above.

Off course too high then tannin can be extracted from the hush (78C ish) so you don't want to exceed that.

 

These are all just guide... Decoction mashes boil some of the grist, easily exceeding 78C and yet don't get the tannin astringent after-taste.. I have no idea why.

 

 

[Darren Andrews (Daza)]

how do you keep the mash so accurate? do you have hot water and cold water close at hand and sit there and watch it during the whole process if was heated with gas and maintaining a specific temp is almost luck surely?

[Sam DT]

For a standard system you get it to temperature and then you wrap it up in insulation as best you can (I use an old sleeping bag). Many people leave it at that, I generally check after 30 minutes and either throw in a little boiling water or give the gas a pump if it's too low. In general I lose about two degrees on a single batch and one on a double over an hour of mashing - I just aim a little higher than my target mash temp so that things average out.

[Dyl]

Youll be amazed at how well a chilly bin holds temperature. I heat my strike water ( thats just the water your using for your mash) to 75ish, preheat my mash tun (converted chilly bin) with hot tap water and then just pour into the mash tun and add the grain while my missus stirs it in. This normally gets me to 66-67 and it will stay at this temp for an hour. I do this inside the house so maybe that helps

[Grant R Baker]

My old chilli-bin mashtun barely lost 1C after 60minutes.. switching to a larger stainless mashtun I now use a recirculation pump, heat source and STC-1000 to monitor the temp of the returning mash water.

 

[Peter Smith]

here is another good Q&A

https://byo.com/hops/item/1314-refractometers-and-mash-outs-mr-wizard

Dear Mr. Wizard:

If you mash at 156° F for sixty minutes and the mash is fully converted, but you have to leave it at the same temperature for another thirty minutes before you mash out, what effect will that have on your mash?

Gerry Steele 
Bloomington, Indiana

Mr. Wizard replies:

This is a good question! Mashing at a single temperature above 150° F strongly favors the enzyme alpha-amylase. Alpha-amylase produces a mixture of fermentable and non-fermentable sugars by breaking down the starches amylopectin (branched starch) and amylose (unbranched starch). Starch reacts with iodine to yield a black color and the mash is said to be “converted” when this reaction ceases to occur. Allowing the mash to stand at 156° F after conversion has occurred won’t have any significant impact on the mash. Most commercial brewers will increase the mash temperature to the mash-off temperature after conversion has been confirmed by the iodine test.

Mash time has a more profound effect on wort when the enzyme beta-amylase is active. Beta-amylase produces maltose from starch and is known as the “fermentability enzyme.” Beta-amylase activity is blocked by branches in the molecular structure of amylopectin and leaves partially degraded starch molecules known as beta-limit dextrins. Alpha-amylase, on the other hand, acts differently and can reduce the size of the beta-limit dextrins. When this occurs, beta-amylase can continue producing maltose. What this means is that alpha-and beta-amylase can work together to produce a highly fermentable wort if the mash rest between 140° F and 150° F is extended. The most effective method to get a really fermentable wort is to increase the mash temperature from 140° F to 150° F over 2 to 3 hours. Some big breweries use this technique to produce light beers with low residual carbohydrate contents.

What I recommend is that you get on with the day after confirming conversion. If you mash-off, go ahead and do it, and if not, start wort recirculation.