BIAB Mash Question

[Ethompson28]

I usually mash for at least 75 to 90 minutes rather than 60 just so I can get as high efficiency as possible. My question is does a longer mash have any possible negative affect or is it basically once conversion is done it's done?

 

[Snicklefritz]

Good question I'd like to hear some answers on this as well. I also typically mash for 75 with a 15 minute mash out.

 

[Rockn_M]

In my opinion once it's done it's done. I use BIAB for pretty much all my brews right now and I do a 60 min mash and I do not have problems reaching my OG.

 

[QuercusMax]

I would be surprised if you'd get better efficiency with a 75 or 90 minute mash than with a 60-minute mash, unless your pH is totally screwed. You may get better attenuation (a drier beer), though. If you're concerned about efficiency I'd suggest stirring the mash a few times during a 60-minute mash, to ensure there are no lingering dough balls.

Shouldn't hurt anything to a couple hours, even, but at some point you're going to start growing some bacteria and getting some funky flavors. Anyone who's left their mash tun uncleaned overnight can attest to that!

 

[misterkidd]

I'm typically a 90 minute man followed by a 5 min mash-out, and I don't think a longer mash does any harm. Since I'm lazy, I don't do an iodene test, so it's a longer mash as I like to be on the safe side. But equally if you do do this test then there's no problem with a shorter mash either, provided that everything's converted. My understanding is that if you mash at lower temperatures you need a longer mash (90 minutes for anything below, say, 145F)...

 

[Foosier]

There are folks who are using very short mashes. For example 20 minutes and less. They are reporting success and minor noticeable differences.

I say that to illustrate that when conversion is done, it is done. The primary reason for a long mash is to ensure that larger cracked grain particles can be fully wetted and the sugars extracted. With BIAB you can crush very fine which reduces the time required to wet the grains. This allows you to mash in a shorter time.

 

[VladOfTrub]

Grinding fine has little affect on sugar extraction, enzymatic action doesn't increase because malt is ground to flour. A fine grind will improve amino acid formation during the proteolytic rest, that's about it. I'm not sure if bag brewers do anything with temperature control, except for choosing a single temperature rest for conversion. So, a rest in the proteolytic range would be out, when the English method is used. Wetting grain and resting at conversion temps for long periods does little to get hard starch into solution. Hard starch begins to burst and enters into solution at temperatures upwards of 168F. That's part of the reason why decoctions are boiled.

Depending on the temperature chosen for conversion, alpha may end up as the primary source for conversion. Alpha creates non-fermentable sugar. The OG might be good. However, the FG might not be so good. Alpha doesn't thermally denature as quickly as beta. Once beta is knocked out, alpha continues to convert starch into non-fermentable sugar. The final product might become imbalanced. Throw into the enzymatic activity process, things like amylopectin, A and B-limit dextrin, gelatinization temperature and pH. Learning about and understanding the role enzymes play in brewing isn't a bad idea. Controlling enzymatic action has an affect on what the final product ends up as.

 

[Magnus314]

The major difference will be how fermentable the wort is. That's measured by the final gravity.

If you're grinding normally, you'll likely get ok to high fermentability. If your grind is finer, you'll likely get very high fermentability/ a very low FG.

A 75 minute mash with a 15 minute mash-out, for me, creates VERY high attenuation... and a FG from 1.004 down to 1.000.