First BIAB - Dissecting Results

[ArcLight]

>>Measured Pre-boil Gravity: 1.049
Measured Original Gravity: 1.058 (5 gal)

>>We were short .5 gallon in the fermenter so we topped off with some water. I forgot to take a gravity reading after I added the water. Is there anyway to calculate it


1.058 measured with 4.5 gallons or 5?



0.5 is a dilution of 10% off of a 5 gallon batch.
1 + .058 * (5 / ( 5 + .5)) = 1.053

Off a 4.5 -> 5 its 1.052
1 + .058 * (4.5 / ( 4.5 + .5)) = 1.052

 

[divrguy]

>>Measured Pre-boil Gravity: 1.049
Measured Original Gravity: 1.058 (5 gal)

>>We were short .5 gallon in the fermenter so we topped off with some water. I forgot to take a gravity reading after I added the water. Is there anyway to calculate it

1.058 measured with 4.5 gallons or 5?

0.5 is a dilution of 10% off of a 5 gallon batch.
1 + .058 * (5 / ( 5 + .5)) = 1.053

Off a 4.5 -> 5 its 1.052
1 + .058 * (4.5 / ( 4.5 + .5)) = 1.052

Did you top off because you we're just short of water or was your gravity too high? If your gravity was ok, I would have just left it. Plus, was your water clean? It appears your gravity was okay based on your recipe. Just volume was off.

 

[OrangesOfCourse]

>>Measured Pre-boil Gravity: 1.049
Measured Original Gravity: 1.058 (5 gal)

>>We were short .5 gallon in the fermenter so we topped off with some water. I forgot to take a gravity reading after I added the water. Is there anyway to calculate it


1.058 measured with 4.5 gallons or 5?



0.5 is a dilution of 10% off of a 5 gallon batch.
1 + .058 * (5 / ( 5 + .5)) = 1.053

Off a 4.5 -> 5 its 1.052
1 + .058 * (4.5 / ( 4.5 + .5)) = 1.052

We got 5 gallons into the fermenter and topped off with .5 gallons. Our gravity aim was 1.055.

Did you top off because you we're just short of water or was your gravity too high? If your gravity was ok, I would have just left it. Plus, was your water clean? It appears your gravity was okay based on your recipe. Just volume was off.

We topped off with bottle spring water that we used to brew so we will have enough when it comes time to bottle. Should we have not done this?

Over all I'd say this batch was a success. There are still a few areas we need to improve but I'm happy with the results so far.

Quick fermentation question: What temperature should I keep the fermentation chiller at to ferment around 63°?

Also: During the first day of fermentation I was unable to refrigerate the batch and it was sitting around 70-78. Will that cause me any harm?

 

[BlueZooBrewing]

We got 5 gallons into the fermenter and topped off with .5 gallons. Our gravity aim was 1.055.



We topped off with bottle spring water that we used to brew so we will have enough when it comes time to bottle. Should we have not done this?

Over all I'd say this batch was a success. There are still a few areas we need to improve but I'm happy with the results so far.

Quick fermentation question: What temperature should I keep the fermentation chiller at to ferment around 63°?

Also: During the first day of fermentation I was unable to refrigerate the batch and it was sitting around 70-78. Will that cause me any harm?

I personally would prefer to have 4.5 gallons of beer coming out with the intended gravity, then having 5 gallons of beer that has been watered down a little bit to hit the desired volume. If I lose a six pack because of it, so be it. It still may taste good, just a little thinner than intended with the recipe.

I agree with the comments about making sure you stir your mash well to make sure your full volume of grist is getting saturated and hitting your desired temperatures. The bigger bag makes it much easier to do that. I consistently hit about 80% efficiency, but I grind my own and grind it finer than pictured.

Another handy toy to keep around is a refractometer. It makes it easier to monitor your conversion as you're mashing so you can adjust temperature and time as you go to hit your desired results.

 

[BlueZooBrewing]

b-amylase appears to be more heat liable at higher water to grain ratios. Here is some data from the Kunze book I have:

(Water to grist ratio)

This would mean that thinner mashes produce less fermentable wort if mashed at the same temperature as thicker mashes. But that has not been my experience. The literature is also divided on the effect of mash thickness on fermentability.

Kai

Reading through the link you referenced with the image, the literature doesn't link the enzymatic activity to a conclusion that thinner mashes produce less fermentable wort. In fact Figure 7 and the associated comments draw the opposite conclusion with regard to conversion of malt starches and production of fermentable sugars, and concluded no impact on the ratio between fermentable extract and total extract.

"Figure 7 shows data from mash experiments done by Windisch, Kolbach and Schild. It shows how the thinner mashes were able to convert more of the malts starch and also produce more fermentable sugars. But the ratio between fermentable extract and total extract (i.e. fermentability) remained largely constant over the range of mash thicknesses that were tested."

It loosely infers that the factors that prepare starches for conversion, and extracts those sugars into solution, operate better in thinner mashes, which more than compensates for the reduced enzymatic residual activity.

"while thick mashes offer better protection for the enzymes, they also inhibit the enzymatic activity through the reduced availability of free water and the sugars acting as competitive inhibitors [Briggs, 2004]. In addition to that the gelatinization of starch is also slower and happens at higher temperatures in thick mashes and as a result thinner mashes are known to give more fermentable worts at normal mashing temperatures."