Is it possible to mash for too long?

damm noobs!

I've got about 8 pounds of grain that has been sitting at 140 or so for an hour. I am doing this in my oven, with the grains in stock pots. In my last few partial mash beers, the oven stayed at an even 150 so I figured that was what it would do this time. I guess the larger amount of grains is messing with the oven temp.

So I turned the oven up a tad and am now closer to 150. the grains have been soaking for nearly one and a half hours now. an hour at 140 and about half hour at near 150. actually, I just took another temp and it's around 144.. dammit.

What effect might this have on my beer?

the iodine test is still turning black so I know I need to soak longer and I'm guessing at a higher temp?

pnj said:

damm noobs!

I've got about 8 pounds of grain that has been sitting at 140 or so for an hour. I am doing this in my oven, with the grains in stock pots. In my last few partial mash beers, the oven stayed at an even 150 so I figured that was what it would do this time. I guess the larger amount of grains is messing with the oven temp.

So I turned the oven up a tad and am now closer to 150. the grains have been soaking for nearly one and a half hours now. an hour at 140 and about half hour at near 150. actually, I just took another temp and it's around 144.. dammit.

What effect might this have on my beer?

the iodine test is still turning black so I know I need to soak longer and I'm guessing at a higher temp?

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A long cold mash... will be a VERY dry beer. Low temps, equal longer to convert.

eh..

Now the grains have been sitting at 150 for another hour and I still get black when I do the iodine test. But the wort is sweet tasting... what gives?

You are getting some conversion if it is tasting sweet. The iodine test works well so trust it. An oven is a poor way to mash. You are much better off with a cooler/mash-tun. They are not too expensive either.

Low temperatures mean a slower conversion, beta amylase is active down to 130F, but alpha doesn't do much down there.

WBC said:

You are getting some conversion if it is tasting sweet. The iodine test works well so trust it. An oven is a poor way to mash. You are much better off with a cooler/mash-tun. They are not too expensive either.

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Heck, he'd be better off with a pot on the stove top and monitoring temps with direct fire.

pnj said:

eh..

Now the grains have been sitting at 150 for another hour and I still get black when I do the iodine test. But the wort is sweet tasting... what gives?

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Stop doing the freakin' iodine test! It's so easy to get a false reading that I find it nearly useless. If you mash for an hour or more at temps from 145-160F, you WILL have conversion.

The iodine test is fun and it's new to me, so why not do it?

I ended up with an OG of 1.050 after all was said and done and now I'm putting together the plans for a cooler mash tun. I learned a bunch during my time last night and that's most important to me.

"The iodine test is fun and it's new to me, so why not do it?"...becasue it's easy to get false results and it's not necessary. Good enough for me....

so sayeth Denny!!! All hail Denny King of the Batch Sparge!!

Nah he is right its all to easy to get a false reading...

WBC said:

An oven is a poor way to mash. You are much better off with a cooler/mash-tun. They are not too expensive either.

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Why is the oven a poor way to mash? I have found it to have very few drawbacks in my brewing process. I get the water to proper temp, add the grains, check the temp and put the whole thing in a warm oven with a remote thermometer probe. I rarely drop a single degree over the entire 60 minutes.

If you'd like to buy me a cooler, since they aren't too expensive, I'll PM you my address. Until then, I see no problems with the oven method.

I used to do the Iodine test but after a ton of batches where I never once got a starch-positive test result...I just stopped doing them. I even tried doing the Iodine test right after dough-in just to make sure I could get a starch-positive test result (which it did). Besides, after a while you can just tell by looking and stirring it if it's converted. It looks different and the consistency/texture changes.

At the higher mash temps the alpha amylase enzyme works really fast...at 158-160 F it might fully convert in 5 minutes. My decoctions do. It won't be a highly fermentable wort but it won't have any starch.

Also, even if you mash-out @ 170 F the alpha enzyme isn't fully denatured and keeps converting throughout the lauter/sparge until you get it hot enough to fully denature them (usually when heating up to the boil).

I mash in a SS pot and just do it on the stove. TBH, I'm not all that concerned with a small temp drop and I can just add a small amount of heat to help it maintain or to get it back up to temp. I am concerned with hitting my initial rest temps and def not over-shooting them...but if I lose a few degrees over 20-30 minutes I pretty much consider it a non-issue. I like to do temperature-ramp mashes anyway (i.e. infuse/strike to rest in the low 140s then slowly heat to hit upper 150s over a pre-determined period of time).

I was under the impression that mashing for really long times (well over 90 minutes) starts to extract a lot of tannins from the husks and other undesirables... no??

Cape Brewing said:

I was under the impression that mashing for really long times (well over 90 minutes) starts to extract a lot of tannins from the husks and other undesirables... no??

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That has never seemed to be a problem.

carl spakler said:

Why is the oven a poor way to mash?

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Because ovens are too small to make a reasonable size mash and some do not regulate heat well at 150F. I brew 12 gallons at a time and because you are doing all the same things, why not make enough to make it worthwhile.

I brew 12 gallons at a time and because you are doing all the same things, why not make enough to make it worthwhile.

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Just devil's advocate here WBC but...because I'd have to brew less often.

I'm already almost to the point where the pipeline is too full for me to brew. I keep buying more kegs but I keep thinking there has to be a limit. I love to brew so brewing less is a bad thing for me.

WBC said:

Because ovens are too small to make a reasonable size mash and some do not regulate heat well at 150F. I brew 12 gallons at a time and because you are doing all the same things, why not make enough to make it worthwhile.

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I don't brew 12 gallon batches nor do I have the space or consumption habits to support that, my pot has no issues fitting in the oven, and if the door is shut and your oven can't maintain the temperature well enough to keep the mash temp. from dropping I suggest a new oven. There is no need to be exactly 150* in the oven, the thermal mass of the mash and mashtun is enough to maintain the temps, the warm oven is just a "blanket" so to speak.

I've been thinking about oven mashing. However, my oven won't go as lower than 185. Do you just leave the oven on or turn it off with the door shut?

Philsc said:

I've been thinking about oven mashing. However, my oven won't go as lower than 185. Do you just leave the oven on or turn it off with the door shut?

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If you have an oven thermometer wait until it hits ~165-170 and then kill the heat. When you open the door to put the mash in the oven temp will drop 10-20 degrees, this will put you in a good range for keeping the mash at the desired temp.

That's what I do. Or did... I bought an Igloo and will use that starting on my next brew. I heated my oven a bit over my mash temp. Mash in, in my spagetti pot and hit my temp, then throw it in the oven. I check the temp after a few minutes and maintain it by turning the oven on for a minute or two at a time. Usually only have to do that once near the start and once about halfway through when I open the door to give my mash a stir. I have an oven thermometer that sits right on the rack next to my pot. Works great. The only reason I'm switching to a cooler is because I want to do more grains and less extract in my PM's.