BIAB efficiency and mash-out questionss

I've brewed 4 batches now using the "Aussie" BIAB method, full volume one pot no sparge. I have seen many places that I am supposed to mash out at 170 degrees. What exactly does this do, as in if I stopped doing it what was the result be. And am I doing it correctly?

My "Mash-Out" is simply raising the temp to 170 F for 10 minutes.


Now onto my efficiency question. I use hopville.com's "Beer Calculus" but being fairly new I don't always hit my volumes. How does that affect my efficiency numbers. For example on my most recent brewday I did this:

7lbs Vienna Malt

ended up with 3.25 gallons
OG of 1.059
efficiency at 86%

I was trying to get 3.5 gallons so I'm assuming my efficiency is lower than calculated, but by how much?


Thanks!

This is my first question I've had to ask, as I have found the search feature to be a blessing.

Mash out stops the enzymes that are converting your starches to sugars from continuing to work and produce undesireable things in your wort.
As for efficiency, you calculate that by finding the ideal extraction (ie what you could get were everything perfect) and dividing your actual by that then multiplying by 100.
here's an example, say you had 10 lbs of 2-row, which has a potential of 36/lb/gallon, your potential would look like (36*10)/5 for a 5 gallon batch, you get an expected initial gravity of 1.072. so now, supposing you actually got 1.065, your efficiency would be (65/72)*100=~90%

Thanks for the answer!

So based on 7lb of Vienna, ending up with 3.25 gallons of wort after the boil I come up with roughly 90% efficiency, but that seems unbelievable to me. Am I doing this right?

Raising the temp to 170 also makes it easier to get the sugars of the grains and into the wort where you want them. Just like cold versus warm honey. Going higher than 170 with the grain in the wort risks extracting bitter tannins from the grain.

When you are doing a brew in a bag, you accomplish mash out by raising the bag of grain (mash) out of the water. You can rinse out more sugar by either sparging or squeezing the bag of grain.

KRamey said:

Thanks for the answer!

So based on 7lb of Vienna, ending up with 3.25 gallons of wort after the boil I come up with roughly 90% efficiency, but that seems unbelievable to me. Am I doing this right?

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you got 78% efficiency

7 * 35 / 3.25 = 1.075

59/75 = 78%

frankstoneline said:

Mash out stops the enzymes that are converting your starches to sugars from continuing to work and produce undesireable things in your wort.

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what undesireable things are you talking about? allowing them to continue working will only further break down your sugar strains allowing them to be more easily fermented.

dcp27 said:

what undesireable things are you talking about? allowing them to continue working will only further break down your sugar strains allowing them to be more easily fermented.

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If you keep the bag in the mash and you arent heating the water to maintain temp I thought the thought was that drops in temperature would produce undesirable off tastes (I may be way wrong, sorry if thats the case)

I have only done 1 other BIAB and it's still bottle conditioning (currently brewing one as I type). I have never conducted a mash out. Do I heat the grains and wort to 170* and hold it for 10 mins? Or just the wort?

I only remove the grains and heat to a boil without any type of mash out temperature hold. Will this effect my efficiency? What other effects could it have on the beer without the mash out temp hold?

a mash out isn't critical and won't have much effect on the beer. because the wort viscosity decreases with higher temperature, a mash out does improve your lautering efficiency of your 1st runnings. however, the change of viscosity from 150F to 170F isn't that much, so its really not much of a bump. if you sparge, its even less of an effect.

i guess it does have some use in ensuring you have full mash conversion, but you should regardless.

Yeah, I think that for BIAB, mash out is over-rated. It may gain you a couple of points.
But if I'm low, it's usually because I've screwed something else up, not because I didn't mash out.
My efficiency changes based on OG as well. I typically get 75% at 1.050, but only about 68% at 1.080. I can get 90% on 1.030; so good notes and recipe adjustment are mandatory for me.

I have never conducted a mash out. Do I heat the grains and wort to 170* and hold it for 10 mins? Or just the wort?

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No, you are going to ideally start heating from your mash temp and take a TOTAL of 10 minutes to go from your mash temp to 170F. So, say you start at 155, you then heat from 155 to 170 over a 10 minute period, ideally hitting 170 right at the 10 min mark.