18 Nov Indiana Brew Kettles: There’s More Than One Way To Stir The Pot
By Mark E. Lasbury for Indiana On Tap
Jerry Sutherlin, one of the uncles of Indiana craft brewing (let’s face it, John Hill at Broad Ripple Brewpub is the father), has opened a new brewery in Indianapolis. After years of brewing at Oaken Barrel, Ram, and Rock Bottom, Round Town Brewery is now a reality that Jerry, along with partners Max Schenk and Eric Fear, has brought to the near south side.
Walter and I stopped during their first weekend of operation in October. We loved the beer and the old building, and the fact that you can reach out and touch the brew house. Max said, “Sure, go back and take a look at the equipment.” So we did. What we found was some beautiful stainless steel and the people who really know how to use it. What we didn’t realize, but Max was nice enough to point out, was that the system is a direct fire gas model, not one of the much more common steam-jacketed kettles.
What, you may ask, is a kettle what does it do, and why does its type matter for making beer? For the first two parts – I can help with those. As to the different types of kettles and why the manner of heating matters – I had no clue. So I called Jerry and asked for a tutorial on boiling water with plant sugars and hops added.
As to the first part of the explanation – the kettle is the boiling cauldron where much of the chemistry (not the biochemistry, that’s in the fermenter) of beer making takes place. You boil beer for several reasons:
Round Town Brewery is named for Indianapolis being the Circle City. That isn’t tough to understand. Go visit them and ask some other questions – they love that. Photo credit: Round Town Brewery
Sterilize the wort – Historically, beer and hard cider were important for keeping people alive before the days of water treatment. For almost two thousand years, much of the drinking water sources in cities and country were contaminated with bacteria, fungi, and parasites. Just as people used to avoid hospitals because they spread so much disease, water was avoided because it could make you sick. The alcohol and boiling of the wort in beer killed disease-causing organisms and, as long as good hygiene was used downstream, made the final product much better for you than contaminated water. Beer is a lifesaver!
Enzyme inactivation – When the malted barley/specialty malts are steeped in hot water in a previous step to make wort, the enzymes in the barley are important for converting long chain starches into short sugar molecules that will be available to the yeast as a food source during fermentation. But, after mashing in, you don’t need those enzymes any longer. Boiling stabilizes the sugars that will be available to the yeast by killing the remaining enzyme activity.
Remove some proteins and tannins – When heated, proteins unfold into long chains of amino acids. These can be a bit sticky and will clump together, trapping other molecules as they float around, including tannins from the malt husks that can make the beer too dry, woody, and unpleasantly bitter. When you see foam at the beach or on streams, or even the foam on top of your soup bones as you make stock – that’s protein foam from flocculation (not like making a Christmas tree white). The protein aggregates from this “hot break” in the boil are scooped off to improve the beer’s flavor and look.
Change the hop chemistry to make beer bitter – Hops are added during the boil for a couple reasons; they are antibacterial (that is why the original IPAs had so much hops, the beer had to stay sterile during a long hot trip to India for the thirsty British troops), and the heat converts a group of hop chemicals (alpha acids) to a different form (iso-alpha acids). The heat just changes the three-dimensional shape by switching the placement of some atoms on the same molecule; it’s called isomerization if you must have a name for it. The longer the hops are in the boil, the more alpha acids will be converted to iso-alpha acids and the more bitter the beer can be. For Dogfish Head 60, 90, and 120 minute IPAs, the time in each name refers to how long the hops are allowed to boil (although many other factors can affect how much isomerization takes place).
Most old kettles for beer were copper because it transfer heat better and the surface wets better, meaning that bubbles are less likely to stick so the boil will roil better. Photo credit: Rutgutis.wordpress.com
Boil off many things that would make beer taste bitter or bad – Many nasty chemicals can be boiled off (volatilized) during the boil to make the final beer taste better. Therefore, a brewer can’t boil wort for a very short time just to have it be less hoppy. The boil is required to get rid of sulfur compounds like DMS (make beer taste like stewed vegetables), although just a bit of DMS is OK in some styles – it tastes a bit like corn. Unfortunately, some good things are also lost in the boil, such as hop oils that give the beer a nice aroma. This is why brewers often add some hops VERY late in the boil, in the brite tank, or sometimes in the fermenter. The oils move out into the beer and will give that nice smell when you dry hop, but none of the alpha acids will be converted to iso-alpha acids, so the beer won’t get more bitter.
Concentrate beer and develop color – Boiling the wort means that water is lost. When it is lost on the macro scale (evaporation), the wort becomes more concentrated. This can be important for beers that need high gravity for their style, like barley wines and such. When water is lost on the micro scale, like when an H and an OH (together they make HOH, also known as H2O) are eliminated from complex sugars. This creates a different kind of chemical bond in the sugar that absorbs more light. It’s this caramelization that makes the beer darker in color and a bit sweeter.
SO…… after that pile of information, one naturally wonders how this boiling is done. I’m glad you asked. There are some basic methods, but they can have some twists. The most common way that commercial breweries boil their wort is in a steam jacketed kettle. The inner tub holds the wort, while a space between the inner and the outer walls is circulated with steam from a boiler. This provides an even temperature through the tank, since all sides are exposed equally to the hot temperature, and the temperature can be controlled fairly well. One gets a consistent boil with fewer hot spots that might burn the wort.
Second, the steam can be moved through the kettle using something called a calandria. The pipes that carry the steam are in the middle of the boil kettle, usually in a tall set of pipes that forma cylinder. This helps the wort roil and circulate through the entire kettle, upward through the middle, over the top of the calandria, and downward near the walls. This also improves the efficiency of the boil because it helps the volatilization of the nasty things you want to get rid of, and evens out any potential hot spots by reducing the time the wort is any one place. There are internal and external calandria, but even Jerry wasn’t sure how external calandrias work, so we’ll pretend they don’t exist.
Lastly, You can boil the wort in the kettle by using direct heat. Gas flame against the bottom of the kettle is the most common way, but some smaller breweries like Cannon Ball Brewing, Books and Brews, and Redemption Alewerks in Indianapolis are opting for electric heat systems. A brewery may pick one system over the other for economic, efficiency, or style reasons. Most breweries bigger than 15 BBL systems use steam jacketed systems, with or without a calandria. Smaller system can go steam, electric, or gas flame, the economics of them actually tend to favor the direct heat methods. So why did Jerry Sutherlin, a brewer of extraordinary experience, choose gas flame direct heat for his new 30 BBL system at Round Town? Mostly because he was used to them and knows he can brew good beer with a direct heat kettle.
The internal calandria helps to roil the boil as well. The beer travels up through the open pipes, the steam is held in the round jacket. The boiling wort spews out the top and circulates well. Photo credit: ProBrewer.com
Way back when, in the days that Jerry was just learning to brew on the Oaken Barrel system in Greenwood – it was direct heat gas brew house. At that time, steam jacketed systems were very new and very expensive. When Jerry moved to Rock Bottom, they had a direct fire system as well. If it ain’t broke, don’t fix it – so Jerry sought a direct flame gas system for Round Town. Of course nothing ever goes to plan; the 15 BBL system for which he put a huge down payment never materialized. The company went belly up and took his money with them to the great beyond. Then he came across a builder with larger gas systems, the one he had in mind for Jerry was 30 BBL – bigger than Jerry had originally envisioned, but hey! – go big or go home.
Jerry explained to me that a gas fire system may have more hot spots and might be harder to control the evenness of the boil, but it does offer some distinct advantages. Caramelization is easier in a direct fire system. You can scorch the malt, with lots of caramelization and more melanoidin formation. Melanoidins are the sugar:protein aggregates that turn your steak a nice brown when you throw it on a hot pan (in chemistry it’s called the Maillard reaction). The melanoidins and caramels taste about the same, but they come about by very different chemical reactions. Scorching malt gives more Maillard reaction and more caramelization, but a little being good does not mean that alot is better. Too much scorch and you just end up with bitter, burnt, wort that is so hard to clean out of the kettle. Caramelization also gives a buttery flavor, from a chemical called diacetyl. Too much diacetyl is not good in a beer, so again, the heating process in a direct fire system must be controlled carefully. However, the advantage is that you can make a heck of a Scotch Ale, Czech pilsener, or ESB with scorched malt. Just consider that when back when ALL systems used to be direct fire – literally a fire built under the kettle, the scorch was controlled according to the style of beer they were making. Nowadays, brewers with steam systems often add melanoidin malts to get the same color and flavor – and this works just fine too. I’ve had some killer wee heavys from steam jacketed systems.
The take home message is that brewers are awfully good at locking in the best conditions for the system they happen to have. Experience is the great equalizer and most brewers are happy with the beer they make on their own system. Illustrative of that point – Jerry told me that despite the supposed limits of a direct gas system, especially at the size he is brewing, he feels it gives him more options, not fewer. But then I talked to a brewer using an electric system, and he said the exact same thing – lots of options. Finally, an unnamed head brewer with a big steam jacketed, internal calandria, system making tons of beer – he said his system offers the most options with the fewest limitations. To each his own; just keep making great beer.
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