Q. I'm looking at increasing the size/brewing capacity of my homebrewery. Right now I am using two 5-gallon (19-L) beverage coolers and they limit me to around 13 to 14 pounds (5.8-6.4 kg) of grain if I mash at a 1.25 qts/lb. ratio. When I upgrade, I want to be able to do bigger beers. How do I determine the grain capacity of any given mash tun of a certain volume?
A. Sizing brewing vessels is part of my job with the Paul Mueller Company. When I am sizing mash mixers for brewing applications where the mash is conducted in a stirred and heated vessel and wort separation is conducted in a separate lauter tun I focus on two primary parameters. The first is the range of grist weights used in the mash and the second is the typical mash thickness (liters of water/kg malt), which is usually between 3.0â€“3.5 in stirred mashes. The mash thickness that you are using is equal to 2.6 when you convert everything to weight. All of the routine brewing calculations I perform are done using metric units. If I want to switch to English units I do this after my primary calculations because metric calculations are much clearer to me.
Mash volume can be calculated by the following:
Mash Volume (liters) =
(Mash thickness + 0.7) x kg malt
The 0.7 in the above equation accounts for the gain in volume that happens when 1 kg of malt is added to water and is empirically derived. Using an example based on your set up I will assume the mash thickness is 2.6 and the maximum grist weight is 14 pounds or 5.9 kg. The calculated mash volume is (2.6+0.7) x 5.9 or 19.5 liters (5.15 gallons). This agrees with your numbers.
Sizing a lauter tun is a different problem. The best way to think of a lauter tun or an infusion mash tun is like a filter. Filters are sized based on area and so are wort separation devices. The critical process parameter to consider is the grist load on the false bottom. This value varies from about 150 kg/m2 on the low end up to about 300 kg/m2 on the high end when brewing big beers with lauter tuns designed for normal strength (12 Â°Plato) lager beers. The grist load is used to determine the diameter of a mash tun or a lauter tun.
Let's look at an infusion mash tun that will be built with a false bottom design (as opposed to a copper pipe manifold), and target a grist load of 250 kg/m2, a relatively normal load for this type of design (infusion mash tuns have higher grist loading than lauter tuns). I want to determine the diameter of this vessel and will begin by calculating the required area based on a maximum grist bill of 5.9 kg. To calculate area, simply divide 5.9 kg by 250 kg/m2 and the result is 0.024 m2 (0.25 ft2). This corresponds to a circle with a diameter of less than 7 inches (A=Ï€r2). And this makes absolutely no sense in the eyes of the homebrewer. Why?
Commercial mash tuns and lauter tuns have grain beds that are considerably deeper than what is used at home. In the commercial world of really high-speed lauter tuns, grain beds are rarely any thinner than about 9 inches (23 cm), and most craft brewers using lauter tuns have grain bed depths ranging from 12â€“24 inches (30â€“60 cm). Infusion mash tuns have deeper grain beds ranging from 24â€“36 inches (61â€“91 cm). So when it comes to designing the homebrew mash tun looking at the commercial world is not as helpful because the design would lead one to build a very odd looking vessel that is tall and skinny. Although the vessel would function, it would be something that could not be purchased off the shelf and would be expensive.
The good news is that designing the mash tun with a thinner grain bed is not a problem, as long as the bed is no thinner than about 6 inches (15 cm) deep. This corresponds to a grist load of about 80 kg/m2 or a diameter of about
12 inches (30 cm). This is more what one would expect and is in-line with the typical 5-gallon (19 L), round water cooler like the one pictured on page 15.
This means that when you upgrade your system you have a few options. You can either scale up using a grist load of 80 kg/m2, or you can scale up using a higher grist load. The advantage of scaling up using a higher grist load is that you may be able to find something readily available that meets your needs rather than staying with the lower grist load value. Whatever you decide, good luck with the project!
Q. How do I add body to my stout? My stout has good aroma and flavor but it seems thin. Is there a way to add more body to it?
A. The old thin-bodied stout is definitely one of the more frustrating flaws for this particular style. From what I have observed, this flaw is often associated with stouts that are brewed in an attempt to mimic the famed dry stouts
of Ireland like Guinness, Murphy's and Beamish. These draught stouts all are dispensed using nitrogen and much
of the body is directly related to the method of dispense. Take away the nitrogen dispense methods and the result is a thinner-bodied dark ale with the alcohol content of a
So, body-building tip #1 is to use mixed gas dispense methods when brewing dry, Irish-style stouts. Bottle conditioning this style or serving it with normal draft equipment is not going to result in the type of stout served at your favorite Irish pub.
The other frequent cause of thin-bodied stout, especially when styles other than dry, Irish-styled stout are considered, comes down to malt selection. It seems that many stout recipes contain pale malt, roasted grains (roasted malt, roasted barley, or a combination of the two totaling about 10% of the total), and perhaps a few other malts thrown in for good measure. Full-bodied beer, in general, begins with a grist bill composed of a variety of grains that have complexity of flavor.
Body-building tip #2 is to beef up your grist bill. If you are using very pale malt, or pale malt extract, as your base ingredient consider adding high-kilned malts like Munich, Vienna, amber and/or brown as a substitute for the pale malt. I also like adding crystal malts to my stouts to add some mid-palate fullness and a bit of sweetness in the finish. The type of crystal can be changed to bring different flavors into the fold based on your personal preferences. I like using darker crystals when I want the raisin and dark toffee notes associated with these sorts of malts. Lighter crystal malts bring a less obvious flavor to the mix. Another classic grain to add to stout is flaked barley or oats at a
rate of 10% of the total grist. These grains are both rich in beta-glucans that add palate fullness. Oats are also known to add a silky, sometimes described as oily, mouthfeel to beer. And both grains slow down wort collection because they increase wort viscosity.
Sometimes beers lack body because the wort strength is simply too low to leave enough extract behind following fermentation to give body. Body-building tip #3 is to increase residual extract by adding more malt to increase the wort original gravity and/or by using higher mashing temperatures to reduce wort fermentability. You can enhance the perception of the increased residual extract by reducing your carbonation levels and serving your beer at temperatures that are warmer than the typical refrigerator. Hopefully there is a cure for your stouts in this answer.
Q. Aside from muslin bags, how can one avoid so much hop sludge when brewing a hugely hopped beer?
@6thFloorBrewing (via Twitter)
A. Copious volumes of hop sludge are a real problem for brewers who are in pursuit of hugely hopped beers because this sludge represents wort loss and batch size contraction. The net result is the inefficient use of ingredients and the reduction of your batch size. In commercial terminology, your material and labor costs are both increased and the opportunity costs associated with your equipment is reduced. Bad, bad, bad! Here are some ways that commercial brewers deal with this very real dilemma.
Solution #1: If you are using pelletized hops you are probably using a whirlpool to separate hops and trub from your wort. When brewing hop bombs you typically have a lot more hop solids to remove. A solution that is very effective is the implementation of a whirlpool vessel with a broader aspect ratio. "Normal" whirlpools have height to diameter ratios around 0.4:1 and very broad whirlpools have height to diameter ratios of about 0.25:1. There is a limit to the practicality of building really broad whirlpools because they become so large in diameter that they are
not practical. They also cease to function when taken to the extreme.
Solution #2: Use whole hops instead of hop pellets and separate the hops from the wort with a hop strainer. Some brewers even add sparge water at this stage of wort production to minimize the wort loss associated with high hopping rates.
Solution #3: Use hop extracts for bittering instead of cone or whole hops. Since the name of the game is hop material reduction, this method is something to consider if you are coupling high bitterness with high aroma. Alpha acid extract can be added to the kettle, or if you want to venture out of the brewhouse you can add iso-alpha acid extract to your beer.
Solution #4: If you are using hop pellets and do not have a whirlpool, let alone a super broad whirlpool, consider collecting the sludge and transferring it to a conical vessel, such as an Imhoff cone (Google search this and you will find plenty of sources). You can allow the solids to settle and then syphon off the good stuff. If I did this I may consider re-boiling for a short period to make sure that I have not contaminated the wort.
Solution #5: This solution is totally impractical for use at home, but is something used by commercial brewers and is interesting to think about. The solution is to use a decanting centrifuge to separate hop and trub solids from wort and to reduce losses normally encountered in the whirlpool to almost nothing. In my beer geek brain, this is an awesome solution to a very real, and potentially very expensive, problem.