Saturday, November 18, 2017

☸️ Beer-making, Part Two

This is the second part of a two-part article. The first part gives a brief description of Wort Hog Brewing in Warrenton, Virginia, a review of one of their beers, and a simple explanation of the first half of the beer-making process. This article finishes that explanation.

The last article left the hot, boiled wort in the boil kettle. Debris from spent hops and proteins have formed a crusty substance on top of the beer, called trub.

The wort requires two things prior to fermentation, the process that will transform it into beer. First, it needs to be separated from the trub, and then it needs to be cooled to a temperature that won’t kill the yeast.

Yeast typically does its thing at a temperature between 50 and 75 degrees Fahrenheit, depending on whether the brewer is producing an ale or a lager. Some beers, notably saisons, ferment at higher temperatures. Lager yeast fermented at higher temperature can produce cream ale, while ale yeast fermented at lower temperature can produce steam beer. Both products require specific strains of yeast that survive and thrive outside their normal profile.

Our wort is just off the boil, and so is considerably warmer.

The wort is swirled in the brew kettle using a metal paddle-like apparatus inside the tank, not unlike the rakes in a mash tun. As a whirlpool develops, solids migrate to the center by centripetal force. Wort is pumped out the side.

The wort passes through a heat exchanger, which is a small radiator with cooling fins that radiate excess heat. The flow rate determines how much heat is dumped into the surrounding air. After heat exchange, brewers inject oxygen into the cooled liquid to goose the yeast.

The wort emerges at the far end of the hose into the fermentation tank at something approximate to fermentation temperature. The fermentation process generates not only carbon dioxide and alcohol, but heat as well. The process is therefore referred to as exothermic, and that excess heat has to be removed right away. Variation in fermentation temperature can produce significant differences in flavor, so fermenters are held at correct temperature by one of several cooling methods. Perhaps the most common is a glycol- or water-filled cooling jacket surrounding the fermenter and circulating to the outdoors, where excess heat is radiated by another heat exchanger. The liquid forms a closed loop, flowing back for another pass.

The fermenter itself is a tall, narrow, stainless steel tank, with a cone-shaped bottom pointing down to the floor. The top is sealed after yeast is pitched into the cooled wort, and a hose emerging from the top leads down into a five-gallon bucket of water sitting on the floor. This bucket is a bubbler. When bubbles of CO2 emerge, fermentation has begun, and when bubbling stops, the yeast is spent. The sealed top prevents ever-present wild yeast and bacteria from entering the wort and altering fermentation. The water in the bubbler prevents these from entering the hose.

(Some brewers, such as Pen Druid Brewing in Sperryville, Virginia, specialize in wild, or spontaneous fermentation. Most brewers eschew wild yeasts and scrupulously clean their equipment to prevent it and bacteria from “spoiling" their product. It’s all a matter of what results are desired. Wild yeast strains and bacteria produce sour beers, which are indeed pleasantly sour. If you’ve never tried it, the style is worth seeking out for the experience. Gose (go'-zuh) and Berlinerweisse (ber-linner'-visuh) are two sour styles, both German.)

Whether using top-fermenting yeast (which rises to the top of the fermenter as it digests sugar) for ale-making, or bottom-fermenting yeast (which tends to settle to the bottom) for lagers, the yeast will eventually die and settle. The conical tank floor collects the spent yeast, and a valve at the very bottom allows for draining the result. A higher-placed valve rescues the beer for its final transfer before tank clean-out.

Going by memory, Wort Hog has four fermenters, so Jeremy can boil up another batch, and another, and another while the first is turning into beer. This is how commercial breweries keep their taps flowing – people are drinking the result not long after fermentation is complete.

What’s now referred to as beer is pumped out to a brite tank in a process called racking. Brite tanks are the final vessel in the beer-making process. The beer sits in these tanks as any remaining solids precipitate out. This is known as fining. Some brewers use filtration to instantly remove finer particulates, while other wait it out.

Settling takes a week or so, and during this time additional CO2 is pumped into the brite tank to carbonate the beer and pressurize the taps. Recall that most of the CO2 bubbles out of the fermenter, so the resulting beer is rather flat. Some like it that way. Others expect more carbonation.

Some beers are enjoyed unfiltered and unfined. The process is the same, without the wait. The brite tank is pressurized and the taps are opened to serve right away. Some of the beer is immediately bottled or kegged, preserving the spent yeast particles that add a distinctive tangy flavor to the beer and are integral to the finished product.

A little added sugar in the keg or bottle lets remaining yeast continue to produce CO2 and alcohol, in what’s known as bottle conditioning. The result is a higher alcohol content and more carbonation.

The next step is opening a tap, drawing a beer, and enjoying.

That’s beer-making. It’s a simple process made more complex by large volume production at commercial brewhouses. Home brewers do much the same with a couple of food-grade plastic buckets, a glass carboy, and plastic hose.

If you’re ever offered the opportunity to tour a brewhouse, take it. The better tours take you up on the beer platform where the brewer works, from which you can see everything arrayed around you.

One final note: much of the process I’ve described is computer controlled these days. All those pumps and valves and heating and cooling criteria are measurable and machine-controllable, and a machine can handle them more precisely than human hands. Even a small, local brewer usually employs some degree of automation in the process of making beer. There’s often as much science as there is art to making beer.

If you’ve enjoyed this two-part series, or any of the other articles on this blog, please subscribe to my RSS feed along the right side of the page, or bookmark us and come back regularly. Comments and corrections are welcome.


Addendum: as is my custom, I stopped in at Wort Hog Brewing this afternoon for a pint and a growler fill. My time in Warrenton is often curtailed by our quilt shop’s closing, but today we’re open late for a special event. More opportunity for time at the bar.

As luck would have it I bumped into Matt and Lou, two of the three owners of Wort Hog, and had a long chat with Lou. The back room, part of the additional space Wort Hog is expanding into, is open now and filled out with tables, chairs, and their regular barbecue provider, Cheat-Ham’s BBQ. Great plans are in store for my local brewery, part of the walkable space of Warrenton, Virginia.

I also bumped into Jen, who poured me a pint or three, and Sydney, whose fun, upbeat self adds to Wort Hog’s allure. Alex was on her way off-shift while I enjoyed my cups, relieved by Tyler, who’s dipped his hand into Wort Hog’s brewhouse and has the world of craft beer before him.

The mezzanine has been redecorated with couches and keg-tables to create a more informal, comfortable space. Think of it as a living room. I could unwind in this space with a pint or two.

I’m obviously fond of these people and the work they do. I’m not easily moved. They, and the beer they serve, are worth a visit.

#WortHogBrewing #beerMaking #craftBeer #process #PenDruidBrewing