Troubleshoot my BIAB recipe!

[Brehwens]

Hi guys!

New to home brewing, I recently started playing around with the recipe creator here on the site and I really enjoy the tool, and seeing how I can affect the parameters of the beer. I have made a couple of "kit" recipes, and felt it was the time to "play around" a bit, and so I created a straightforward lager recipe:

https://www.brewersfriend.com/homebrew/recipe/view/751671/modern-lager

So: I wanted to have 10 L going into the fermenter. As I did a BIAB, and from a previous run (and internet wisdom) realized I would loose appr. 2 L of water in the grains, I heated 12 L for my mash.

According to the recipe, I was expecting an OG of 1.049. With 9.5 L in my kettle after mashing, I was at 1.066.

Adding more water, I was at 1.054 at 12 L. Final post-boil OG was 1.052 at 12.3 L (approximately). So I came fairly close, no big deal. But I ended up with 2.3 L "excess" wort, as I had to dilute the wort.

My questions:

1. How should I use "batch size" in the recipe calculator when doing a BIAB? I understand that the grains absorb water, but do they not also absorb the sugar dissolved in the water? (in other words, should the BIAB step be considered a "concentration effect" or a "bulk loss effect"?
In my case, I realise I had too much grain/too little water for my mash, but I can't really get my head around the water volume I should enter as the "batch size" when doing a BIAB. For my recipe to add up, giving the OG I actually got this corresponds more to a batch size of 9.5 L (which is what I got after taking out the grain bag), but to me it sounds strange if I were to always add a certain amount of water/kg grain, as the IBU calculations then would be performed on a volume that is not there when the hops are actually added. Do I make sense?

2. The point of the "estimated boil size" to me is unclear: During the boil, one can concentrate or dilute as one wants to reach the volume to which the hops amounts have been adjusted to.

Please check out the shared recipe (link above) and give me your thoughts on this!

Best regards, and all the best for 2019!

/Karl

 

[Ozarks Mountain Brewery]

welcome to the site and good luck brewing

 

[Mark Farrall]

There's a few more areas where you've also got to keep track of where you lose volume apart from grain absorption. The best place to see them is to go to the tools menu in your recipe and choose quick water requirements.

For your recipe the values are:

• Total mash water needed 19
• Grain absorption losses -2
• Starting boil volume 17
• Boil off losses -4.5
• Kettle dead space -0.5
• Hops absorption losses -0
• Amount going into fermentor 12
• Total: 19

These are largely driven by your equipment profile. If you haven't already you should start by updating the values in https://www.brewersfriend.com/homebrew/profile/equipment. If you don't know a value just leave it as a default. You can ignore mash thickness as you're not sparging.

For full volume BIAB the places where you're likely to change the defaults are:

• Grain absorption losses - if you squeeze the bag the default will be too high,
• Hop absorption losses - as for grains, if you squeeze the default is too high,
• Boil off losses - if you're on a stove top and you don't get a vigorous boil this might be too high as well,
• Kettle dead space - if you're just pouring the kettle into the fermenter set it to 0

So update those and go back to your recipe and see if the values in the quick water requirements come closer to your first batch.

And batch size is generally used to represent to the amount going into the fermenter and estimated boil size is the amount of wort that should be in the kettle prior to starting the boil (so final volume + boil off losses + hop absorption losses + kettle dead space).

edit: the dilution/boil off calculator is great if you're trying to adjust things at the last moment (https://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/). Personally I just wear the shortfall or overshoot and adjust the recipe for next time. I've stopped caring whether a particular batch hits the correct numbers. I'm now more interested in the next batch being closer to the recipe/profile.

Generally they taste just as good if they're a little lower or higher in ABV and I've made more batches worse by changing things near the end of the boil than I have by letting it ride.

 

[GFHomebrew]

What he ^ said . It will take a few batches to get an idea where you loss are. Keep at it and enjoy the process and more so the beer.

 

[Brehwens]

Thanks for your input so far guys!

A question on the grain absorption though: is it thought that the absorbed water also contains sugar, or is it in fact only a loss of water?

In order not to end up with a larger starting volume than necessary, I'll think I will calculate with a near zero boil-off loss as I will compensate with boiled water at the end of the boil.

So in my case, the batch size will essentially be the batch volume plus the grain absorption volume (which was in my case probably more than a litre even if I squeezed the bag)

I will rework the recipe and see if I can make sense of the volumes

 

[Mark Farrall]

Hmm, not sure, but I guess some of the sugar solution would be absorbed. But that's probably tiny as on the way to being as hydrated as it wants to be it would be absorbing the clean water and then the very, very dilute sugar solution. I'm guessing that it's so small that it doesn't affect the calculations.

 

[Craigerrr]

How much unconverted starch, or how much fermentable sugar does not make it into the kettle contributes to overall efficiency. Don't get hung up on whether you could have put 3 or 4 more grains of sugar in your coffee.

There are losses all throughout the brewing process. What you want to do is to gain an understanding of what, and where those losses are in your system, and account for them. The goal is to get the end result you planned for, as opposed to squeezing every last ounce of beer out of a batch.

 

[Nosybear]

The recipe builder actually does a pretty good job of tracking losses. Lost sugar to grain can be approximated: Take a gravity reading of second runnings. Let's say you get 1.010. A pound of grain soaks up about 0.5 quarts of liquid so if you have 10# of grain, you have 5 quarts of water remaining in them. Alternately, you could weigh the grain before and after to get the actual mass of water left behind but for now, let's go with the assumption built into the recipe builder. 5 quarts is 1.25 gallons, multiply times the 10 gravity points to get 12.5 points of gravity left behind. Divide by 46 ppg for sugar to get 0.27 pounds, or 4.35 ounces of sugar left behind. Not enough to worry about at our scale.

 

[thunderwagn]

Just my personal opinion, but I think the Brewers Friend water calcs are kind of a pain in the ass when first starting with BIAB. I much preferred using this calculator to really pinpoint what was happening and setting up my equipment profiles. After a few batches, and using this calculator, and comparing it to Brewers Friend, it was much easier for me to get my water amounts dialed in. This calculator also gives you some calculations and measurements that BF doesn't, which personally, I find useful.
https://pricelessbrewing.github.io/...ssFermTrub=0.5&Gabs=0.08&Habs=0.0365#Advanced