20 min. BIAB batches. Are they ok?

[jcorn]

Have brewed extract and mostly partial mashes for the past 4.5 years. I used to almost all of my ales on a 20 minute boil with late extract additions and level out my ibu's on a calculating app (BrewR for Android) and thanks worked flawlessly for me. I have brewed 5 batches of all grain BIAB this year with the same 20-30 min. Boils and just using more hops to make up for the ibu's. My ag brews have turned out so amazing but after doing some searching it seems no one else partakes in these short boils.
Is there a reason why I should NOT boil for 20 mins. on biab batches besides making up for the hops (which I do)? Am I hurting anything only boiling for such a limited time?

 

[RM-MN]

There is another reason for doing the hour long boils. It's known by its acronym, DMS which stands for dimethyl sulphide and if it is present in your beer you will notice a cooked corn flavor. Boiling longer will drive off the precursor, SMS, so you beer won't have this. With that said, most malts have little SMS to be boiled off so you can get by with the shorter boil as the yeast will drive off or consume any DMS that is still present. The exception to this is Pilsner malt which really should have a longer boil.

With all that said, how long do you mash while doing BIAB? 60 minutes, 90 minutes, 30 minutes?

 

[jcorn]

I typically mash between 60-90 minutes. Typically about 75 minutes. From the 5 or 6 biab mashes I have done all have been base grains of 2-row and hardly any pilsner malt. I have mashed munich, crystal 60, carapils, crystal 10 and crystal 75. I have not noticed any cooked corn flavors in my brews. So I am safe to boil for 20 min. as long as I do not use any Pilsner malt? If I do use pilsner malt, how long would I have to boil to burn away the DMS that the yeast may not be able to take care of ?

 

[pkrath84]

I want to say that the time in the boil is also to allow for complete starch to sugar conversion. Does that sound right?

Edit: I just read a thread asking about 90 min boils and it was said that 60min should suffice, but 90 may be necessary in some brews. In regards to extract, it was mentioned that while DMS precursors are present, the amount isnt significant enough to warrant longer than a 60 min boil.

 

[CBMbrewer]

I want to say that the time in the boil is also to allow for complete starch to sugar conversion.

This is incorrect. The conversion of the starches to sugar takes place during the mash.

 

[kaconga]

It really depends on the style if beer and how you want to approach it. For most beers I would say a 30 min boil is possible. However, some beers derive their chracteristics from a long boil. In some cases even 2 or more hours. There may be shortcuts for this by using melanoiden malt and such. If it works for you then keep rocking it. I like the 60 minute boil because hops are one of my most expensive ingredients.

 

[RM-MN]

I typically mash between 60-90 minutes. Typically about 75 minutes. From the 5 or 6 biab mashes I have done all have been base grains of 2-row and hardly any pilsner malt. I have mashed munich, crystal 60, carapils, crystal 10 and crystal 75. I have not noticed any cooked corn flavors in my brews. So I am safe to boil for 20 min. as long as I do not use any Pilsner malt? If I do use pilsner malt, how long would I have to boil to burn away the DMS that the yeast may not be able to take care of ?

If your grain is crushed/ground fine enough you could get full conversion in less than 30 minutes so a 75 minute mash is just a waste of time. If you have iodine, check your wort just as you mash in (should turn dark blue indicating starch) and another sample at 30 minutes. I'll bet the iodine won't change a bit.

With that in mind doing a 75 minute mash and then saving time with a 20 minute boil seems wrong.

 

[Yooper]

With that in mind doing a 75 minute mash and then saving time with a 20 minute boil seems wrong.

That's what I was thinking! Since the grain is well crushed in a BIAB, it's probably likely that the mash had full conversion in 20 minutes or so, and I've seen it happen even in traditional mashes. Most people go 60 minutes just to be extra sure there was enough time for complete conversion.

You could check the mash with iodine to make sure, if you wanted to save time, and do a 30 minute mash.

As far as a short boil goes, lots happens in the boil besides hops utilization. Not only does the boil get rid of the DMS precursors, it condenses the wort some (increasing the gravity), coagulates proteins, and allows maillard reactions to happen to make the wort "richer".

Far more good info from our wiki: https://www.homebrewtalk.com/wiki/index.php/Boiling_the_Wort

If I needed to save 40 minutes badly, I'd cut it off of the mashing side and still do a 60 minute boil. Some brewers (like Jamil Zainasheff) are proponents of 90 minute boils, even without pilsner malt, due to the benefits a boil provides (including clearer beer).

 

[jcorn]

I never ever would have imagined that a 30 minute mash would do all the conversions that a 60 min. mash would do. The reason I cut my times to begin with was trying to get to bed earlier on nights i brewed during the work week. I will try a 30 min. mash and go back to longer boils. Now onto the discussion of how short of a boil I could get away with and if 45 mins. would cut it. Hop utilization was the only thing I was ever aware of with boil times. I noticed this short boil stuff after one of my beer kits a few years ago had me out extracts in at flameout.

 

[C-Rider]

That's what I was thinking! Since the grain is well crushed in a BIAB, it's probably likely that the mash had full conversion in 20 minutes or so, and I've seen it happen even in traditional mashes. Most people go 60 minutes just to be extra sure there was enough time for complete conversion.

You could check the mash with iodine to make sure, if you wanted to save time, and do a 30 minute mash.

As far as a short boil goes, lots happens in the boil besides hops utilization. Not only does the boil get rid of the DMS precursors, it condenses the wort some (increasing the gravity), coagulates proteins, and allows maillard reactions to happen to make the wort "richer".

Far more good info from our wiki: https://www.homebrewtalk.com/wiki/index.php/Boiling_the_Wort

If I needed to save 40 minutes badly, I'd cut it off of the mashing side and still do a 60 minute boil. Some brewers (like Jamil Zainasheff) are proponents of 90 minute boils, even without pilsner malt, due to the benefits a boil provides (including clearer beer).

I do 2 gallon batches (BIAB) and lately noticed that BeerSmith calling for 75 min mashes. For a few batches I took SG readings w/my refractometer every 15 min and noticed a big change in the SG over time. I can't imagine a 20 or 30 min mash as getting all the sugar out of the grain. Right now I'm doing the 75 min mashes and getting like 80% Eff.

 

[RM-MN]

I do 2 gallon batches (BIAB) and lately noticed that BeerSmith calling for 75 min mashes. For a few batches I took SG readings w/my refractometer every 15 min and noticed a big change in the SG over time. I can't imagine a 20 or 30 min mash as getting all the sugar out of the grain. Right now I'm doing the 75 min mashes and getting like 80% Eff.

I've done a bunch of BIAB 2 1/2 gallon batches and with a 30 minute mash I was getting about 85% efficiency. If it takes 75 minutes to get full conversion, your grains aren't milled fine enough. Conversion takes very little time but with too large of grain particles it takes much more time to leach the sugar back out.

 

[jcorn]

The best I have done is 71% efficiency at 153/154 for 75 mins @ 2qts. Per pound

 

[Yooper]

The best I have done is 71% efficiency at 153/154 for 75 mins @ 2qts. Per pound

BUT- you don't know if you had full conversion at 20, 30, 40, 60, or 75 minutes if you didn't test for conversion.

In general, a warmer mash will convert faster. Also, adjuncts (oatmeal, corn) take longer to convert. A 158 degree mash with two-row and Munich mash should convert in 20-25 minutes, while a 147 degree mash with two-row and lots of oats may take 90 minutes.

The only way to know if you've reached conversion is via an iodine test. If the iodine doesn't turn black, there is no starch.

There are other reasons to mash longer, but if I was so pressed for time I needed to desperately save 30 minutes so was considering a 30 minute boil for an AG batch, I'd cut it from the mash (probably) instead of the boil.

 

[jcorn]

Yooper, you are definitely right on the fact I need to start doing an iodine test along with my refractometer samples. I am going to try the 30 minute mash on my next batch (zombie dust clone) and see what happens. Bad news on the side of things: My first encounter with this dms problem that was spoken of: I brewed 2 citrusy apa's 2 weekends ago and both are around 1.020 gravity with safale 04. One beer tastes pretty good and on target for what was expected. The other citrusy pale ale turned out really WEIRD! It tastes very cooked vegetable like. The grist was 10lbs 2row, 1 lb. Carared and 1lb crystal 60. I guess only time and hopeful dry hopping will kill this weird flavoring off. I even put some amylase enzyme into the fermenter to try and dry the hell out of that beer and hopefully get some more work of my Safale 04 to drive off this DMS.

 

[Yooper]

Yooper, you are definitely right on the fact I need to start doing an iodine test along with my refractometer samples. I am going to try the 30 minute mash on my next batch (zombie dust clone) and see what happens. Bad news on the side of things: My first encounter with this dms problem that was spoken of: I brewed 2 citrusy apa's 2 weekends ago and both are around 1.020 gravity with safale 04. One beer tastes pretty good and on target for what was expected. The other citrusy pale ale turned out really WEIRD! It tastes very cooked vegetable like. The grist was 10lbs 2row, 1 lb. Carared and 1lb crystal 60. I guess only time and hopeful dry hopping will kill this weird flavoring off. I even put some amylase enzyme into the fermenter to try and dry the hell out of that beer and hopefully get some more work of my Safale 04 to drive off this DMS.

No, DMS won't go away during fermentation unfortunately. It's there to stay.

 

[jcorn]

Guess I could add some nice mesquite chips to the fermenter and turn it into a corn flavored roasted smoke ale!

 

[C-Rider]

I've done a bunch of BIAB 2 1/2 gallon batches and with a 30 minute mash I was getting about 85% efficiency. If it takes 75 minutes to get full conversion, your grains aren't milled fine enough. Conversion takes very little time but with too large of grain particles it takes much more time to leach the sugar back out.

That could be. I double mill at the LHBS. There is a range of crush when finished. But I'm happy w/the high efficiency. Gonna change my BeerSmith rating from 75 to 78% to save a "little" on grain. LOL