Saint Arnold (b. 580, d. 640) is the Patron Saint of Brewing. In his lifetime, he was known for encouraging local peasants to drink beer instead of water (as water sources were frequently contaminated in those days). These days, Saint Arnold lends his name to a microbrewery (b. 1994) in Houston, Texas. I have a long history with Saint Arnold brewery. I have known the owner since college and was the first volunteer for the weekly Saturday tour, eventually giving the tours myself. I have even become Saint Arnold, immortalized as the bobblehead (shown right) before I finally joined the staff, first as a Brewer and then as the Brewery Production Manager. Saint Arnold sponsors a wide range of activities that promote our hobby and has long offered their facilities (including the walk-in cooler) for judging The Dixie Cup, which is the Foam Rangers annual competition. In this article, I’ll relate some of the things Saint Arnold taught me and how they can be employed at the homebrewing scale.
A Homebrewer Goes Commercial
Size matters, as they say. Yet the processes used in making beer really aren’t that different between the homebrewer and the professionals. It’s more about the size and complexity of the equipment you’re using. Even so, bigger and better equipment doesn’t guarantee good beer or even consistent beer. You have to have processes in place to compensate for the variables which affect your final product.
That was my greatest lesson learned in transitioning from a homebrewer to a professional. There’s no magical wand that you use to ensure quality and consistency, it’s all about the processes you use to create the exact same product every single time.
Coming from a homebrewing environment, where each batch had its own character, the notion of reproducing the same beers every day to the same exact specifications seemed almost impossible. Indeed, my own attempts at brewing the same beer twice were often thwarted by varying ingredients, gravities and alpha acid levels. What was a homebrewer to do?
My former boss, and owner of Saint Arnold, Brock Wagner, at times described the 30-barrel DME system at the heart of the brewery as a “glorified homebrewing rig.” (Note: DME here refers to name of the company that fabricated the brewhouse vessels, not the commonly used homebrew acronym for dried malt extract.) Indeed, any homebrewer would instantly recognize the two vessel system as analogous to an all-grain homebrew system. Grain was ground and augured into the mash tun, allowed to steep, sparged and transferred to a kettle and then chilled as it was run off to the fermenter where yeast was waiting to do its work. What could be simpler?
The real key to producing consistent wort is to compensate for the variables you get in every mash. Grist quality will vary based on kernel sizes and composition. Efficiency will vary based on how loose or thick your mash is. Conversion will vary based on how accurately you hit your strike temperature. The alpha acid levels in your hops will vary year to year, even with the same varieties. One way the pros correct for these variables is to use a volumetric system of wort production. When you get down to it, all of the nuances of making wort boils down to getting the right concentrations of sugars and isomerized alpha acids every time. The beginning homebrewer follows that exact model when brewing with malt extract. A given volume of malt syrup and water should yield a wort at a given specific gravity.
For a commercial brewer (or all-grain homebrewer), however, the same amount of malt in the same amount of water doesn’t yield a wort with the same gravity time after time. Even if you have calculated your average extract efficiency, every batch is a little bit different. In order to hit their expected original gravity dead on, the brewers at Saint Arnold do the following. They begin with a 30-barrel formulation of the recipe they are brewing. However, they know ahead of time that their average extract efficiency is higher than the formulation uses. In other words, they expect to collect enough extract to brew more than 30 barrels. After runoff, they measure the volume of wort collected and its specific gravity. Later, as the boil nears the end, they add boiling water to adjust their volume upwards and arrive at the exact starting gravity of the beer.
Applying that basic concept to the homebrew scale is simple. What we want to do is determine how successful our mash was by taking an initial gravity reading when the boil begins. It is essential that this gravity reading be taken quickly and accurately, so a glass cylinder is used for the hydrometer and it is quickly cooled to the appropriate temperature for the most accurate reading. If the reading is delayed, concentration of the wort will have already begun, giving a false starting point. Using that initial value, we then determine a final volume to achieve the desired gravity. After that you compensate for evaporation (remember it is based on the initial gravity, not the post-boil gravity) and arrive at a volume driven value that informs your hop level correction, if any.
The initial equation (equation 1) looks like this:
End of Boil Volume (V2) = [Initial Gravity (G1) x Initial Volume (V1)]/ Target Gravity (G2)
where the two terms for volume can be expressed in gallons or liters, as long as you are consistent, and the gravity terms are in gravity points (the three decimal points after the one in your specific gravity; for example, SG 1.045 equals 45 gravity points)
The volume correction equation (equation 2) looks like this:
Volume Correction (for hop additions) = [End of Boil Volume + Evaporation – Batch Constant]/Batch Constant
So what, pray tell is a batch constant? This is the batch size you planned for, albeit knowing that your actual yield will likely require you to make a volume adjustment. The evaporation term is the volume of wort evaporated during the boil.
At Saint Arnold, the company goal is to deliver over sixty barrels of beer for packaging every time they brew. To accomplish this, they brew two thirty-barrel batches to fill a sixty-barrel fermenter. Consider for a moment what that means. Starting with kettle loss (trub and hops) then yeast loss after fermentation and finally filtration loss, there may be several barrels in a sixty barrel batch that are lost in standard production.
The same is true for homebrewing, but on a smaller scale. Most homebrewers simply aim for five and a half gallons (21 L) of wort to get a five-gallon (19-L) batch. So the goal has to be something larger than what you intend to finish with. In the case of Saint Arnold, that’s part of the difference between making money and losing it.
The key is to be intimately familiar with your kettle. You should know exactly how much liquid is in it at any given time. The brewery has a nice engraved scale (pictured at left) which hangs in the kettle that is easily read. My ten-gallon brew pot has a stainless steel spoon with engraved level marks on it that are calibrated to that specific pot. The finer the resolution of the marks, the easier it will be for you to accurately dilute (or concentrate) your wort to the desired strength.
So let’s run through an example. Assume a batch constant (BC) size of 5.5 gallons. Saint Arnold’s Amber has a target gravity (G2) of 1.0545. Now let’s say that our initial runoff volume (V1) is 6.5 gallons at an initial (pre-boil) gravity (G1) of 1.056. (In other words, we have more wort, at a higher gravity, than our target.) Thus, to calculate our end of boil volume (V2):
V2 = [G1(V1)]/G2 = (6.5 gallons x 56)/54.5 = 6.68 gallons
So, at the end of the boil, we will need to add enough boiling water to bring our volume up to 6.68 gallons. How much water we need to add depends on how much volume is lost during the boil. (You can see how a properly calibrated scale will come in handy, although I think it’s possible to “eyeball” and come pretty darn close.) Kettle evaporation for a 90-minute boil at sea level is about 10% of the volume (according to Dave Miller’s “Homebrewing Guide”), so 0.65 gallons will evaporate.
Knowing the volume that will evaporate will also allow us to adjust our hop amounts as per equation 2 :
VCH = (6.68 gallons + 0.65 gallons – 5.5 gallons)/5.5 gallons = 0.33
What that means is that your alpha acids need to be about 1⁄3 greater (remember your calculated final volume is larger than your batch constant) to achieve the same hopping level as the original. Multiplying the hop levels by 1.33 will give you the correct level. (Given that most homebrewers have brewing software, the hop calculation could also easily be done by simply changing the batch size in the software, and adjusting the hop amounts to reach the target IBU value. Multiplying the amount of each hop addition by the ratio of the new volume divided by the original volume will get you there.)
Of course, the amount of bitterness in a beer depends not only on the amount of hops added, but their alpha acid levels, and these differ between different seasons and crops. The Cascade hops in the Saint Arnold recipe were at 6.0% alpha acid in 2008, while the 2009 crop is at 7.5%. One way to correct for differences in alpha acid levels is:
Old Alpha / New Alpha = Alpha Correction in this case 6 / 7.5 = .8
So you can get the same alpha acid levels by using 80% as much of the new crop. That will be combined with the 1.33 correction required by the volume of wort. So overall, we have:
Original weight x Alpha Correction x Volume Correction or 1 x .8 x 1.33 = 1.064
It is important to note that you need only to adjust for alpha in hops that are providing bitterness. Flavor, aroma and dry hops still need to have the volume adjustment made. (And again, another option is to use brewing software, if you have it, to do this calculation.)
Having made all the required adjustments, only one remains to be executed, adjusting the final volume. Ideally this is done with near boiling water right at the end of the boil, so that you can boil a few moments, add your zero minute hops and proceed to chill. If you have been tracking your liquid level on your scale, then it’s a simple matter to measure out the required volume and add it at the right time. With practice, a good brewer can hit within a point or less of target gravity every time.
Water and Yeast Nutrition
Of course, once you have your wort, you still have to ferment it. At Saint Arnold there is a reverse osmosis system that reduces water to its bare bones, but of course bones aren’t exactly what you look for when it’s time for a meal. Yeast need nutrients and reverse osmosis water has many of these nutrients removed. Interestingly enough, regular tap water has a lot of what yeast needs. What you don’t need is the chlorine that comes with it. A simple charcoal filter will take care of the chlorine. The solution applied at the brewery was to set up a blend of mostly reverse osmosis water with charcoal filtered city water mixed straight in. Of course, every city’s chemistry varies, so your mileage may vary. One thing is for certain though, reverse osmosis and distilled water lack the desired level of micronutrients that allow yeast to thrive. Beyond that, water salts can be adjusted to suit whatever you’re brewing. Just don’t use “bare bones” water.
Sanitation — Feel the Heat
Even with healthy and vital yeast, competitive strains of bacteria aren’t what any brewer wants for his wort, which leads me to another “pro” level method of ensuring an organism-free environment, heat (in the form of hot liquid or steam). The most significant benefit of heat is that it penetrates surfaces, even scratches, fittings or gaskets that might harbor stray bacteria. Of course, using heat on a homebrewing scale can be dangerous. Glass carboys can break, plastic can melt and you can scald yourself if you are not careful. It is ideally used with stainless steel vessels, but can be used with extreme care on other materials.
Most of professional brewing remains the common sense methods good homebrewers use. The difference is process, everyone in the brewhouse doing the same things, the same way and achieving the same results. That process allows you to reproduce the same results, the same way every time. While it sounds rather boring, consider the implications. Once you know how to produce the same beer, the same way, every time, you have total creative control over your products. You can alter one variable at a time to bring about new creative visions. I recently had the privilege to interview Tomme Arthur of Port Brewing Company and his Lost Abbey series of beers exemplify that mentality. From a warehouse brewery like Saint Arnold’s old facility they are starting to catalogue the intricacies of barrel maturation so that it can become a consistent part of the brewer’s toolkit.
My own time in the brewhouse was both the most stressful job I ever have held, but also the most fun. Meeting the exacting standards requires skill. Meeting the rigors of lifting, climbing and cleaning requires physical endurance. Meeting the people who enjoy the beer is pure joy.