Why use Carapils/Dextrine with BIAB?

I've seen a few recipes tailored fro BIAB that use Carapils/Dextrine.

What is the purpose of using this, especially when brewing in a bag?

What is different about BIAB vs. traditional brewing where Carapils is needed?

To start with, i'd challenge the notion that Carapils is needed anywhere.

Carapils is just a crystal/caramel malt that's very light in color; as such, it adds some unfermentable sugars that increase the body and sweetness of the beer.

There shouldnt be a difference in how it's used, whether it's BIAB or a traditional mash/sparge setup. In both techniques, it still accomplishes the same thing.

i very rarely use any crystal/caramel malts, choosing kilned base malts (vienna, munich) and slight bits of debittered black malt for colour correction instead
to me the beers taste cleaner

There is nothing inherently different brewing with BIAB vs traditional brewing other than the processes. Using Carapils/Dextrine malt is just pretty common among people when building beers to give the beer body without adding a lot of sweetness or color. Now in some styles it is very common and others not so much.

I personally have talk to a lot of people that use Carapils and wheat malt in every recipe just to make sure the beer turns out with body and head retention. To me that is just a crutch that you should avoid. If you brew the beer right your beer will have the qualities it should have without leaning on Carapils and wheat malt to make it a certain way.

I know this is a few months old, but I BIAB exclusively, and recently read that the higher water to grain ratio of the mash produces a slightly more fermentable wort than a traditional mash. If that's true, you could end up with a slightly thinner beer, in which case a handful of carapils could be used for balance.

What I'm wondering is could you alternatively mash 1–2 degrees higher, and how would that differ from adding 1/4–1/2 lb of carapils.

I've been thoroughly pleased with my brews using BIAB, but depending on the style, I might try this method to get a little more "chew" that I wouldn't say is lacking, but maybe just 5% short or so ...

I'm very curious to hear some responses. I had never heard of this phenomenon, but it would explain why our first BIAB ended up with an FG much lower than expected. It was a gumballhead clone, and FG was supposed to be about 1.012. Ours ended up at 1.006. The mash started at 153 and only dropped to about 150 after 75 min, so all in all I thought I was doing pretty well for a first go at all-grain.

marvinsjunk - I'm with you on the lower than expected FG. While not completely BIAB, I do mash in a bag and regularly attain lower FG. For example, my last batch of Double Dead Guy Ale started @ 1.084 and dropped to 1.010. It was supposed to be in the 1.018 to 1.020 range. Mashed @ 152 (I use a thermapen) and fermented @ 60 (using a thermowell and fridge).

Technically, I am confident in the temperatures.

Something unknown to me dried it out a little more.

My PM brews OG's are typically 1.043 to 1.060 with FG's from 1.010 to 1.012. About the same ranges as my AE beers. I typically mash 5-6lbs of grains in 2 gallons of local spring water & sparge with 1.5 gallons. This gives 3.5 gallons boil volume in my 5G BK/MT that I can easilly handle to get as much wort volume to top off water as possible.
I usually add 1/2lb of carapils as a matter of course. But since I also use a couple different base malts with crystal,chocolate,roasted malts,or others,I'm wondering if leaving out the carapils would be ok? Some beers,like my hybrid lagers,seem to need it after several weeks at room temp & a week or more fridge time. Even that seems to vary with regard to head volume & retention. But also having some chill haze problems,I've been rethinking the grains,crush,mash,etc. I started wondering too if leaving out the 1/2lb of carapils might help clear it up a bit more by introducing fewer proteins?

I think for the next BIAB I'm going to try a thicker mash and see what that gets me. For this first one, I mashed in a 5 gal beverage cooler (on sale at Menards for $10 ) and it was filled to the brim, including 12 lbs of grain. I believe the mash thickness worked out to be about 1.5. Maybe try 1.0 and see what happens.

I also dunk sparged on the first one just for a few seconds. Maybe that rinsed a lot of highly fermentable sugars and left the less fermentables behind. For the next one I'll try leaving the bag in the sparge for 10 min and stir it around a bit. Should help efficiency too.

From talking to a friend who is a pro, I gather that a thicker mash will usually lead to a fuller bodied beer.

Carapils is often used for head retention and body, as was mentioned earlier. I don't think it should be viewed as a crutch though. Today's very well modified base malts are highly fermentable, and often won't produce the long chain sugars that build mouthfeel unless mashed quite high. Therefore many brewers (and breweries) add Cara and crystal malts and other adjuncts to improve certain aspects of the beer.

If you BIAB with a thicker mash, you probably need to do an extra batch sparge step with your additional water amount. One of the benefits to the thin mash that BIAB utilizes is that it is actively sparging during the mash, and you don't need to do that extra step. I've done around 15 BIAB batches and every beer has turned out excellent with regard to body and the FG is usually on target. Though I may explore mashing 1 or 2 degrees higher OR adding a bit of carapils to future batches just to see what differences might occur.

I stir my mash every 20 minutes or so, and go 60–90 minutes, and always do a mashout rest for 10 minutes at 168. I also squeeze the bag and set it in my bottling bucket to drain the rest of the goodness while I bring the pot up to boil, then add it to the pot.

Regarding carapils/foam I read either on a bottle of Founders brew or their website that they "love carapils" and use it up to 15% in some brews!

When altering a recipe though, I am either going to add 1/4–1/2lb of carapils (if it's not already there) OR adjust the mash temp 1–2 degrees if it already has carapils.