Ask Mr. Wizard

Increasing Mash Efficiencies


Tim Jennings - Chicago, Illinois asks,

I am looking for ideas to help me get more yield from a batch of my homebrew. I figure the time spent for mashing (I brew all-grain), fermentation, racking and packaging all take about the same amount of time whether I net 5 gallons (19 L) of beer or 4 gallons (15 L). My problem is that I never get anywhere close to 5 gallons (19 L).


This question reminds me of a phone call I once received from a winemaker who was considering building a brewery, and the plan was to build a 400-barrel brewhouse (12,400 gallons per batch). This made my ears perk up as I was thinking that the brewery in planning would have an annual capacity of at least 500,000 barrels per year. I was wrong. The idea this fellow had was to install very large equipment and only brew once a week. While this may be appealing from a labor point of view, the capital investment required for this person’s sort of plan is impossible to justify based on labor savings over a rational time frame. But the general concept does indeed have merit.

The first thing I would consider is to brew larger batches if you want more beer for one very simple reason; there is always some loss encountered during brewing. If you simply want to improve your efficiency for the challenge involved, that’s one thing, but if you feel like you are not generating enough beer from a batch to justify the time required or to satisfy your demand, brewing larger batches can help address that problem.

But there are some techniques to help improve the yield from a batch. The most common sources of loss in brewing are encountered during extract recovery from malt (mashing and lautering), wort loss associated with hops and trub, and beer loss associated with foaming during fermentation, yeast, racking and/or filtration, packaging and beer dispense. The most common topic discussed by brewers is brewhouse yield. Although this is an important topic for a number of reasons, such as ability to formulate new beers, ability to consistently brew and economic considerations, poor brewhouse yield does not equate to loss of volume. A brewer with an inefficient brewhouse can make up for this by simply using more malt than a brewer with a more efficient brewhouse to produce the same wort volume.

As the popularity of very hoppy beers continues to spread, brewers continue pushing the hop addition envelope. One of the huge downsides to some of the methods being used is wort and beer loss. Wort loss increases in the whirlpool process used to remove pellet hop solids when hopping rate increases and beer loss increases during racking when dry hopping is used. Some large commercial brewers are using centrifuges to reduce wort loss after whirlpooling.

Although this method is out of the reach of the homebrewer, and most small commercial brewers, the idea is pretty simple; recover wort typically discarded with hop solids. An easy and relatively inexpensive method that can be used at home is to collect the trub and separate the wort from the solids using an Imhoff cone. I will leave the details of this method for another day, but this basic idea will definitely reduce loss. Kettle finings, e.g. Irish moss, are very effective at increasing the density of protein flocs precipitated during boiling and improve the separation of trub from wort. And if you really want to push the homebrewing envelope, the use of hop extracts can all but eliminate hop solids from the whirl-pool process . . . there is much more to using hop extracts than simply replacing hop cones or pellets with extracts, so calm down if this seems like a silver bullet!

Beer loss during fermentation is so common that many brewers assume that “blow-off buckets” are a requisite of a well-appointed brewery. This sort of loss drives me crazy and is not limited to homebrewing. While tepid fermentations with little activity are often indicative of real problems with yeast pitching rate or yeast health, fermen-tations that gush beer from the top of the fermenter are certainly not models of perfection. Properly sized fermenters are large enough to accommodate foam, designed to safely vent carbon dioxide out of the fermenter and permit the beer to ferment with-out losing product. This is easy to address by simply using a larger fermentation vessel. There are some fermentation methods that are designed to skim brandhefe (literally translated as “burned yeast”) or braun hefe (brown yeast) from fermenting beer. These include Yorkshire Squares, Burton Unions and a variety of lager fermenter designs with foam chambers, but all of these methods are designed to minimize beer loss, whereas the blow-off bucket is simply a method to control the mess associated with this unmanaged loss.

Racking loss is a loss that is pretty difficult to eliminate because the greatest source of the loss is beer tied up with the yeast at the bottom of the fermenter, and unless a centrifuge is used to separate beer from yeast, this loss is always present. Racking loss can be minimized, however by selecting yeast strains that have good flocculation traits that lead to thick sediments that are easy to leave behind in the bottom of the fermenter.

Like wort loss, racking losses are affected by hopping. Dry hopping is a great method, but with it comes inherent losses. There are numerous methods being explored by some of the larger craft brewers to address this very real and expensive loss. Additionally, the traditional method of simply adding hops to the fermenter is not the most efficient method of extracting hop aroma compounds. So the losses are two-fold when it comes to dry hopping, and both forms are expensive. Some of the newer dry hopping methods include containing the hops in a small vessel through which beer is pumped, for example, the Torpedo method developed by Sierra Nevada, hop removal using a centrifuge, and methods aimed at increasing the aroma yield from pellet hops by more effectively dissolving the pellets prior to addition. Many brewers are also looking at hop extracts to address these issues.

And finally there is loss associated with packaging and dispense. Most homebrewers are either bottle conditioning or kegging their beers and these methods typically do not result in high packaging losses, as compared to packaging carbonated beer. Beer dispense, however, frequently does result in high losses that are, for the most part, entirely controllable. The use of refrigerated keg boxes, “jockey boxes” with cold plates or cooling coils, and the elimination of sections of beer line exposed to ambient temperatures help to reduce foaming associated with warm lines. Proper pouring techniques — specifically the implementation of patience — help to further reduce dispense losses. Emulating the practices seen in most bars where bartenders pour foam down the drain is something to avoid since beer foam is about 50% beer. If a foamy pour is allowed to settle and patience is used during dispense, losses, which typically hover around 10% for many bars, can virtually be eliminated at your home bar.

Response by Ashton Lewis.