For all-grain brewers, mash efficiency refers to the percentage of available sugars that are extracted from the malt into the wort. A mash efficiency of 70-80% is typical for most homebrewers, though it is possible to get upwards of 90% mash efficiency.
Mash efficiency matters for a couple different reasons. For one, you want to be able to hit your estimated original gravity. Too low, and you could miss the market on alcohol content, flavor, IBUs, and mouthfeel. Secondly, by improving mash efficiency, you can essentially brew more beer with less raw ingredients. Commercial brewers pay special attention to mash efficiency, because just a percentage point could mean the difference of hundreds or even thousands of pounds of grain – quite an impact on the bottom line!
Though a couple points in mash efficiency improvement may only be a difference of a few dollars for us homebrewers, it’s still something worth paying attention to. Here are 6 tips for improving mash efficiency.
- Get a good crush. One key to getting good mash efficiency is getting a good crush on your homebrew grains. The objective is to expose the starchy insides of each kernel while maintaining most of the grain husk to use as a filter bed during the lauter/sparge step. If you don’t crush the grains very well, you could hurt your mash efficiency and miss your original gravity. On the other hand, crushing the grains too much could result in a stuck mash. You can exercise strict control over your crush by using your own grain mill.
- Mash longer. Sometimes improving mash efficiency only takes a little more time. If you normally mash for 60 minutes, try a 75- or 90-minute mash to see if that helps your mash efficiency. This can be particularly helpful if you have trouble reaching your desired mash pH (see below).
- Control your pH. pH is one of the main factors affecting mash efficiency. Though a mash will convert at a neutral pH, it works best around 5.4. Use a pH meter to monitor mash pH, and if needed, try using gypsum or lactic acid to lower your mash pH.
- Do a protein rest. A 15- to 20-minute protein rest can help break down the cellular structure of the grain, making starches within the grain more accessible. On the flip side, a protein rest can harm body and head retention, so you may want to compensate with extra Carapils or crystal malt. Still, improving mash efficiency may be something a simple as a protein rest.
- Identify lost space in your mash tun. It’s important to account for mash tun losses when figuring out how much grain you need to reach a target pre-boil gravity. For example, if you need 6.5 gallons of wort, but leave behind half a gallon of wort in the mash tun, you need enough grain to create 7 gallons of wort. Many homebrew calculators have inputs for this number. Paying attention to your mash tun losses makes it much easier to hit your target extract efficiency.
- Don’t oversparge. Adding too much sparge water can dilute your wort and hurt your mash efficiency. Try to use only as much sparge water as you think you’ll need to maximize your mash efficiency.
If all else fails, it’s ok to add a little DME to your wort to bring your original gravity up to target range. But dialing in your mash efficiency will save money on raw ingredients and make it easier to develop accurate homebrew recipes.
Do you have any tips for improving mash efficiency? Share in the comments below!
David Ackley is a beer writer, brewer, and self-described “craft beer crusader.” He holds a General Certificate in Brewing from the Institute of Brewing and Distilling and is founder of the Local Beer Blog.