Efficiency

[Buell]

I’ve brewed 5-6 BIAB batches I’m I’m comfortable with the process but I’m having a hard time grasping the efficiency concept.

If I’m buying pre-made recipe kit, do I even need to know my setup efficiency?

Or do I need to know that to help me hit the correct OG?

Confused..

 

[BobBailey]

There are 2 different efficiency numbers most brewers are concerned with. Mash efficiency is the percentage of available sugars you extract from the grains. Brewhouse efficiency is the percentage that actually makes it into the fermenter.

As for efficiency numbers being useful when brewing kits, you answered your own question. They will definitely help you to predict your OG. Also, if you don't come close to your predicted OG, they will help you isolate the reason why.

 

[tomwhit19]

i think im going to say this correctly, or at least along the right line because this took me awhile to grasp myself, and i still stumble on it from time to time

mash efficiency is measured by how many of the converted sugars from the mash make it to the boil so even if youre doing BIAB from kits where all the grains come milled and ready to go, doesnt mean your efficiency is going to be as high as you want. if a mistake is made or if you miss your mash temp or if you lose wort to a spill or something youre going to lose efficiency

example - if your preboil volume is supposed to be 6.5 gal @ 1.035 gravity and you only collected 6 gal for the boil at that gravity your efficiency will be lower

like i said i may not be 100% accurate with that but i believe im on the right track of it

 

[IslandLizard]

Most kits are tailored to 75% mash efficiency. Using BIAB you may get higher efficiency, especially when you mill the grain yourself or remill it finer. Since the bag is your (tight) filter, you can mill it to almost powder. That increases mash speed, mash efficiency and thus usually total brewhouse efficiency too.

If you end up with too high a gravity each time, keep some of the (base) malt behind and make a "special" brew every 5-10 brews from all the saved grain. Or live with the bit higher gravity and alcohol it produces.

Or, if you want and have the extra space in your kettle and fermentor you can increase your boil volume to get the proper gravity. You'll get more beer. If you're kegging, you can't fit more than 5 gallons in a keg, so there will be good beer leftover. You can fill plastic soda bottles with it and use a carbonation cap.

 

[Buell]

Soo..
If I take a reading pre-boil, that gives me the efficiency of sugar extraction.
Post boil reading gives me OG, correct?

I have John Palmers How To Brew Book but it is lacking in some areas..

Thanks for the great responses so far!

 

[Gnomebrewer]

I measure efficiency at three points.
1. Mash conversion efficiency - measured in the mash. There aren't many calculators for this one. This should be close to 100% (certainly above 90%). It is the percentage of the total sugars that can possibly be extracted from the grain before sparging. I recently started using braukaisers spreadsheet for this one http://braukaiser.com/documents/efficiency_calculator.xls
2. Mash lauter efficiency - efficiency in the boil (start of boil or end of boil should both be the same). This is the efficiency of extracting sugars into the kettle. It's the actual gravity divided by the maximum possible gravity for a given volume of wort in the kettle. Some wort will be left behind in the mash tun, so this is lower than mash conversion efficiency.
3. Brewhouse efficiency - measured in the fermenter. This is the overall efficiency into the fermenter. It's the actual gravity divided by the maximum possible gravity for a given volume of wort in the fermenter. Some wort is typically left behind (trub) in the kettle, so this is lower than mash lauter efficiency.

Note that I use the term 'sugars', which is not technically correct. It includes dextrins and other soluble non-fermentables, including starch if conversion isn't complete.

The reason it can help to measure all three is that you understand your system better - if efficiency is low, you'll know which point is the culprit.

 

[IslandLizard]

Soo..
If I take a reading pre-boil, that gives me the efficiency of sugar extraction.
Post boil reading gives me OG, correct?

That is correct.

If you lower your mash volume by a bit (either forced by limited kettle volume or voluntarily) and reserve some of that water for sparging the bag, and also squeeze it each time you drain it, you can eek a few more points out, raising your (mash) efficiency.

 

[RM-MN]

Or, if you want and have the extra space in your kettle and fermentor you can increase your boil volume to get the proper gravity. You'll get more beer.

This is a great idea for a beer that has only base malts. However, if your efficiency is very high and you add water to compensate for that without adding more caramel or roasted malts if the recipe calls for them you get a (slightly?) watered down beer because you will have diluted the flavors. It will be much better to adjust the base malt before the mash, saving it for future batches as you also suggested.

 

[IslandLizard]

This is a great idea for a beer that has only base malts. However, if your efficiency is very high and you add water to compensate for that without adding more caramel or roasted malts if the recipe calls for them you get a (slightly?) watered down beer because you will have diluted the flavors. It will be much better to adjust the base malt before the mash, saving it for future batches as you also suggested.

The biggest problem with most kits is the grains are premixed and usually milled, so you can't just remove the base malt.

Brewing with higher efficiency will get you somewhat higher gravity (and alcohol), but generally not much more color and flavor from the steeping grains either, although finer milling might help with that, as does more thorough sparging.
That said, if given the choice, I tend to favor brewing at the bit higher gravity (and resulting higher alcohol) over having a bit higher volume with the risk of it tasting a bit bland.

Most recipes are pretty robust in variations of their ingredients anyway. Increments are typically in 4 or 8 oz, so it's not all that precise either. Then there are differences in the actual malts used.

So if efficiency of an all grain kit recipe goes up from it's designed 75% to an actual 85%, we're looking at a 13% net gain. That's significant! And as you said, that gain is not all across the board, from elements that may not increase much at all, to others that, due to much better conversion and/or lautering, are even higher.