"over-convert" your mash?

[ejearn]

As a noob, it seems that longer mash times can yield higher efficiencies, say a 90 minute mash. Is there any concern about extracting undesired flavors from the grain when doing a longer mash?

 

[the_bird]

If your pH is too high, I suppose it's theoretically possible you'd start extracting some tannins. 90-minute mashes aren't uncommon, though, the longer mash basically allows the enzymes to convert some of the longer-chain (unfermentable) dextrines into shorter-chain. fermentable sugars. Longer mash times will tend to promote a more fully-attenuated beer. If I'm doing a big Belgian, for example, something I want to finish pretty dry, I'll usually let the mash sit for an extra 30 minutes.

 

[wyzazz]

Some do sour mashes overnight or even longer, so yes you could "sour" your beer by leaving a mash too long but 90mins won't to that AFAIK.

 

[starrfish]

Many times my iodine test is not complete at 60min and I'll let it ride another 30min for a 90 min mash.

 

[redalert]

My best beer so far has been a Smoked Porter that was mashed for 12 hours! It tasted like porter and a fine Belgium that was aged for some time. I actually prefer longer mash times. Perhaps its subjective but not only do you I get better efficiency but somehow I think the wort is more rounder and complete with the full flavor of the malt coming through.

 

[Revvy]

Some do sour mashes overnight or even longer, so yes you could "sour" your beer by leaving a mash too long but 90mins won't to that AFAIK.

Some folks do non sour overnight mashes as well. As long as you keep the temps up out of sour range.

 

[jbrookeiv]

If I'm doing BIAB, would a 90 minute mash be a good idea then?

 

[devilishprune]

Most of the time, unless you want something special, you only need to mash until you have full conversion. Leaving your mash for longer than that isn't going to magically make you more efficient.

There are a set amount of starches in your grains that are going to be converted into shorter chain sugars. There is a way to calculate your mash efficiency, and if it isn't close to 100% then you are having issues somewhere.

Check this out: http://braukaiser.com/wiki/index.php/Understanding_Efficiency#Measuring_conversion_efficiency

Most of the efficiency loss (in my system anyway) is due to lautering dead space, and not to an inefficienct conversion.

 

[GilaMinumBeer]

Conversely, often times even a 60 minute mash is an extended mash. when the starch is gone, it's gone. Going longer won't make it goner.

If anything, going longer may give more time for non targeted amylase to cleave more chains thus altering the target fermentability or tactile character of the beer. Unless you are at the extreme ends of temp and pH range for a given set of enzymes, the opposing enzyme are still at work just with limited efficiency.

 

[the_bird]

Conversely, often times even a 60 minute mash is an extended mash. when the starch is gone, it's gone. Going longer won't make it goner.

If anything, going longer may give more time for non targeted amylase to cleave more chains thus altering the target fermentability or tactile character of the beer. Unless you are at the extreme ends of temp and pH range for a given set of enzymes, the opposing enzyme are still at work just with limited efficiency.

That's the thing, you can have conversion but just converting those sugars to starch doesn't mean all those sugars are as fermentable as they can be. The logic of the extended mash isn't to get more conversion, it's to get a more fermentable wort. Now, how much of an impact it actually has... I don't have any data, but would love to hear some if somebody does.

 

[devilishprune]

Your wish is my command:http://braukaiser.com/wiki/index.php/Mash_Time_Dependency_of_Wort_Fermentability

It seems like a difference of 2 hours makes only a 4% difference in apparent attenuation, with the largest increase happening at 90 minutes. So if we can apply these results to a wide variety of scenarios, it seems that mashing longer than 90 minutes isn't going to do you much good in terms of attenuation either.

The way I see it, you wouldn't mash for longer than 90 minutes unless you don't have time to complete lautering at the moment, want to do a sour mash, or have a stuck sparge.

Also, be sure to check out that website for the future. I took some time and read nearly all of it, and I feel enlightened for doing so.

 

[the_bird]

Figured if ANYONE had done the data, it would have been Kai! Thanks.

 

[ejearn]

So, basically, ensure proper pH, extending my mash time to ensure complete conversion or a more fermentable mash should not result in extraction of off flavors and what not; i.e. RDWHAHB. Thanks for the feedback!

As long as I have you all on topic, if I add say 0.5 lb carahel with the goal of having more dextrines for more body, would an extended mash time reduce the effect of the carahel by breaking down the dextrins to simpler sugars (assuming an infusion mash at lets say 152 deg.).

 

[funkswing]

if I add say 0.5 lb carahel with the goal of having more dextrines for more body, would an extended mash time reduce the effect of the carahel

Nope, but 0.5 lbs of Carahell in a 5-6 gal batch isn't going to give a whole lot of perceivable body, esp when mashed at 152 F. If you are going for more body I would would mash at 154-158 F to lower the attenuation. Yes, cara/crystal malts do add body to the beer, but when its only 5% of the grist the mash temp will be the dominate variable regarding perceivable body.