Calculating your system’s separate efficiencies is the first step to dialing in your equipment and setting yourself up for good consistency from batch to batch. The term “efficiency” is used quite often throughout the industry and can have different meanings to different brewers. Here at Deutsche, we like to look at three points of efficiency measurements to help define how well our systems perform and help guide recipe building. Typically, we’ll look at conversion efficiency, lautering efficiency, and then overall brewhouse yield. These calculations can be very valuable as you calculate your needs for future batches, and to know when adjustments are necessary to the equipment or to the process.
Conversion Efficiency: Maximum Yield Versus Actual Yield
Conversion efficiency is determining the efficiency of the mash process your equipment created. It involves measuring and comparing the extract of the wort created during mashing versus the theoretical maximums of extract from the grains. The results of the calculation can demonstrate how well you converted all available starches from the grains prior to lautering and sparging. There are automatic differences in potential based on the type of grain used. The average pale malt will typically give an approximate 80% maximum yield with perfection in the brewing system.
Step #1: Grain Points
We’ll need to begin with the maximum potential of the malt. This is generally provided by the manufacturer and recorded on the datasheet for paler malts. It may be listed as ‘DBFG’ or ‘Extract %’. For some darker malts, this may not be provided and may have to be estimated based on similar malt listings online. The first thing to understand is how to record this for calculation purposes. This will usually be reported by only the last two digits. For instance, the DBFG of a pale malt might be 1.041. This would be noted as ‘41’ grain points. It is also possible that only a percentage, such as 83% will be provided on the datasheet. In this case, it is given as a comparison to one pound pure sucrose in one gallon of water, which has a specific gravity of 1.046, or 46 grain points. Therefore, an 83% implies: .83 * 46 = 38.18, 38 grain points.
Step #2: Total Grain Points
Multiple the grain points by the pounds of that malt, then divide that by the volume of the mash, and sum those figures for all malts included. For instance, you might have a mix of three individual malts in a 250-gallon mash:
Malt #1: DBFG of 80% = 36 grain points
Malt #2: DBFG of 77% = 35 grain points
Malt #3: DBFG of 68% = 31 grain points
Malt #1: 500 pounds: 500lb * 36 grain points / 250 gallons = 72
Malt #2: 200 pounds: 200lb * 35 grain points / 250 gallons = 28
Malt #3: 100 pounds: 100lb * 31 grain points / 250 gallons = 12.4
Total = 112.4 total grain points
This can be looked at as the maximum potential yield of your recipe, as it does reference the maximum amount of sugar that can be pulled from the malt mix.
Step #3: Calculating Conversion Efficiency
The last thing to do is to take a specific gravity reading of your wort after the mash and compare that to the total grain points calculated in the previous steps. For example, let’s assume your first wort produces a specific gravity of 1.108.
1.108 = 108 grain points
CE = 108 grain points / 112 total grain points * 100 = 96.4%
Your conversion efficiency is 96.4%
Conversion efficiency should always be in the high 90s or even be able to hit a true 100% if mash parameters were performed correctly. If mash efficiency is not in the 90% and above range, you’ll want to investigate mash parameters that affect conversion—including temperature, pH, time, grist crush size, mash thickness, the presence of dough balls, and if any mash steps were performed.
Lauter Efficiency: Separating & Rinsing Efficiently
Lauter efficiency is looking at the extract of wort in the kettle post lautering and sparging, prior to boiling. It utilizes the same calculations as conversion efficiency but is looking at pre-boil kettle volume and extract. In the example above, after lautering and sparging, if we collected 500 gallons of 1.050 wort at kettle full, lauter efficiency would be 50/56.2 = 89%.
Factors that may affect this efficiency number include:
- Properly designed lauter tun diameters, taking into account grain bed depth
- Sparge creating an even rinsing of grains during run-off and preventing channeling
You will most likely find you’ll have different lauter efficiency numbers across lower gravity beers versus higher gravity beers, due to the effects of grain bed depth. Hopefully, if your system was designed properly these differences will be slight and the lauter tun will be accommodating to low and high gravity beers.
Overall Brewhouse Yield
Overall brewhouse yield considers “into the fermenter”, efficiency which looks at the gravity of extract and volume of wort, post knockout cast, into your fermenter. This calculation can point out losses within the system. Having previous conversion and lauter efficiencies can help determine where the greatest losses are happening— at the boil, whirlpool, or knockout.
I’ve been very pleased and honestly impressed with how efficient, intuitive and true to recipe design our new Deutsche 5 bbl, 3 vessel system has been. I had to quickly produce 5 batches on the new system to be released for our anniversary celebration and not only did the beers come out great, the efficiency of the system proved to be significantly better than we anticipated. 4 of the 5 batches were returning beers from years prior and the resulting batches were very tight to the original brews if not even cleaner and more balanced than the last time we had produced them on a large scale. What was also impressive is how the system stayed highly efficient even though the grain bills, hop bills, original gravitys and mashing processes for all of the brews were dynamically different.
– Chad Henderson, Head Brewer/Co-Owner, NoDa Brewing Company.