The living part of beer

Yeasts are the living stars of the beer brewing process. Their work remained a secret for hundreds of years of brewing, but once brewers discovered their microorganism partners, they learned to use different yeasts’ characteristics to their advantage.

Yeasts are eukaryotic microorganisms, mostly unicellular, and vary largely in size from about 2 µm in diameter to 40 µm. They are classified in the kingdom Fungi, and have diversified to approximately 1500 different species. For the most part, yeasts reproduce asexually through mitosis, and often new yeasts may simply form as an outgrowth of existing yeast through “budding.”

The work that yeasts performed secretly for so long in the brewing process is called fermentation. It is the process by which they convert carbohydrates (sugars from the grains) to carbon dioxide and alcohols. Historically, brewers recognized that fermentation took place, but they did not understand the details of the underlying mechanism. Beer was exposed to the open air, which allowed natural yeast and bacteria to “infect” the beer, consuming the sugars and producing alcohols. One natural yeast is the Brettanomyces Lambicus strain, which produces sour beers descended from the lambic traditions of Belgian brewing.

Scientists in the 1800s began learning more about yeasts’ role in the environment in general as well as in brewing. In 1837, Theodore Schwann showed that yeast was alive, and by 1860, Louis Pasteur was able to connect yeasts to the fermentation process. He demonstrated that yeasts exposed to oxygen simply multiply, but when deprived of oxygen, cause a fermentation. Pasteur invented pasteurization to kill yeast, thus halting fermentation, which allowed more control over a number of food and drink production processes. Pasteurization was applied first to wine in 1864 at the request of Emperor Napoleon III to save his ailing wine industry, and about a decade later to beer (Pasteur authored his Etudes sur la Bière in 1876).

Later, brewers noted that the two main types of beer yeast are ale yeast (the “top-fermenting” type, Saccharomyces cerevisiae) and lager yeast (the “bottom-fermenting” type, Saccharomyces uvarum). The former operate at temperatures ranging from 10 to 25°C and rise to the surface during fermentation to create a thick yeast head. The latter work best at temperatures ranging from 7 to 15°C, and tend to settle at the bottom of the fermenter as their work progresses.

Today, brewers take advantage of yeast by-products in addition to alcohol, which impart much of the flavor and aroma on beer. Examples of these flavor compounds include acetaldehyde (green apple), esters (fruit), diacetyl (butterscotch), 2,3-pentanedione (honey), organic acids (sour or salty), fatty acids (soap), and dimethyl sulfide (cooked sweet corn). Brewers choose particular yeasts for their fermentation processes based on these byproducts, according to their desired aromatic and flavor profiles for the beers. For instance, German Hefeweizens often have distinct hints of banana courtesy of isoamyl acetate, the same ester found in abundance in one of the most popular fruits on Earth.

Next time you appreciate a good beer, take a moment to consider all the hard work accomplished by the yeasts, and imagine which ones were used to create the particular profile of the beer. They worked unappreciated for so long, so it’s up to us to celebrate their accomplishments – after all, they have supported networking and the creation of social connections for centuries.

An entryway to design, entrepreneurship, and beer



Much like Venture Café, Portico Brewing Company sees itself as an accessible entryway into another world. For Portico, that world is craft beer. This Thursday, Alex Rabe, co-founder of Portico, will visit Venture Café to conduct guests through that delicious entryway.


Named for one of the most ubiquitous architectural structures in the world, Portico Brewing Company focuses on the unassuming nature of its beer and markets its product to the everyday consumer who is considering a taste of craft beer. Like their logo, the Portico beer tap handles – one of which we will display this Thursday – reflect an emphasis on minimalism, featuring the brewers’ favorite pieces of architecture with a black and white design.

Portico arose from a love of entrepreneurship and beer. It was founded in the summer of 2012 by three Babson MBA graduates: Alex Zielke, Alex Rabe, and Ian Chester. The team spent over a year home brewing, incorporating Zielke’s skills as a certified Berlin Brewmaster, and hosting tastings with their friends. After several strategy sessions to figure out how three Babson MBAs should go about founding a brewery, they began to brew “gypsy style” at Watch City Brewing Company just down the road in Waltham, Massachusetts.

To date, Portico has produced four beers: a Belgian inspired Kolsch called Fuzzy Logic, a summer sour named Rendition, a fall Farmhouse Ale dubbed Saison Charrette, and a winter Scotch Ale christened Sett Seven. We will be serving Fuzzy Logic, Portico’s flagship beer, in the Café on Thursday. Kolsch is a traditional German beer from Cologne, Germany, but Portico’s version combines North American barley and wheat with German hops. This combination results in a balance of citrus and sweet malty flavors, with only a slightly bitter hop profile. The brewers use Belgian yeast, which makes Fuzzy Logic “Belgiany,” creating a fruit and floral aroma. The result is a smooth, refreshing beer, tasty to the everyday consumer or the craft beer aficionado.

This Thursday, walk through the portals of Venture Café to taste Fuzzy Logic, and to meet one of its makers. You might just learn about two Venture Café favorites: entrepreneurship and craft beer.

Keg Coupler Madness!

Robin and Shahin, still basking in the glory of our Eurobeer experiment with the S-system keg coupler, opted to forge ahead with our beer diversification initiative for Venture Café. Our crash course in keg coupler technology has taught us much about the inner workings of beer dispensing systems, knowledge that we feel obligated to share with our fellow beer aficionados. First and foremost, all keg couplers are not created equal.


First unveiled in Operation Keg: Part 1, this project has encountered only one minor hiccup to date. Deceived by an incorrect photo on a vendor website, we mistakenly ordered plug connectors for the beer lines with retractable white plastic stoppers (top photo) that restricted flow more than we might have liked.



Last Thursday during the Café, we replaced the errant connectors on the S- and D-system couplers with unvalved plug connectors (bottom photo). Problem solved!

During lunch hour on Friday, following the fortuitous arrival of two additional 5/16” plug connectors for the gas lines, we outfitted our brand-new G-system and A-system couplers with their very own quick-release valves, allowing them to join the august company of the previously retrofitted D- and S-system couplers. (Micromatic, the fine purveyor of the Venture Café’s keg couplers, maintains a reasonably comprehensive list of beer brands with corresponding keg taps.)


The A-coupler, aptly nicknamed the “German Slider,” engages the beer line by sliding sideways onto the keg. German breweries Warsteiner, Hacker-Pschorr, Paulaner, and Spaten, among others, distribute their wares A-compatible kegs. Well-known brews from the UK such as Boddingtons, Fuller’s, and Tennent’s use the G-system, as well as the Dutch brand Grolsch. Anchor Brewing Company in San Francisco made a name for itself in the 1980s as a contrarian by adopting the G-system instead of the D-coupler used by the vast majority of American beermakers. In recent years, Anchor has caved to peer pressure somewhat. Although they still distribute ½ and full barrel kegs with G-system connections, 1/6 kegs of Anchor beer are D-coupler compatible.


As shown in the photo above (along with Shahin’s hand), the G-coupler, named after the UK manufacturer Grundy, has an O-ring configuration similar to that on the German Slider, but the beer line is engaged by twisting onto the fitting at the top of the keg. At first glance, the beer inlets of the D- and S-couplers also look quite similar. However, because the probe on the S-coupler is longer and narrower than its counterpart on the D-coupler, they cannot be substituted for one another. D- and S-couplers are sometimes referred to as American and European Sankey couplers, respectively.
Who exactly was this Sankey character? An inquiring mind wanted to know. Naturally, I turned to that formidable fount of fantastic factoids otherwise known as Google. As it happens, Sankey refers to GKN Sankey Ltd. (now GKN plc). GKN (formerly Guest, Keen and Nettlefolds), a multinational producer of components for the automotive and aerospace industries headquartered in Worcestershire, England, has a storied history. The company evolved from an ironworks founded in 1759 during the early stages of the Industrial Revolution. The Sankey in question was Joseph Sankey (1826-1886), a producer of steel tea trays whose company, Joseph Sankey and Sons Ltd., began manufacturing auto bodies and steel wheels in the early 20th century. Sankey & Sons was acquired by GKN in 1920. The combined entity continued to diversify, entering the airplane engine turbine blade market in the 1950s. In January 1977, the U.S. Patent and Trademark Office issued Patent #4,002,273, entitled “Dispense Head for Liquid Containers” to Cyril Golding and Eugene Leonowicz, assigned to GKN Sankey Ltd. of Telford, England. Figure 1 looks familiar:


Unfortunately, the Sankey brewery products business did not survive the manufacturing downturn in the UK during the 1980s, but the Sankey name (often misspelled as “Sanke” on beer websites) lives on.
Reading through the Sankey patent confirmed that all of the various and sundry keg couplers designs serve a common purpose– dispensing sanitary, good-tasting beer with just the right amount of carbonation. Modern beer kegs are equipped with a spear, a long metal tube that extends inside the keg down the middle from the ball valve at the top of the vessel, terminating at an open inlet near the bottom. The spear facilitates the uniform dispensing of beer at all liquid levels.


Pulling the handle down and pushing it into the groove in the side of the coupler opens the CO2 valve. When connected to a gas canister but not to a keg, seating the handle causes CO2 to rush out around the rubber O-ring at the bottom of the device. The act of mating the coupler to the keg by twisting clockwise (or sliding in the case of the A-coupler) pushes down on the ball valve at the top of the spear. Beer flows upwards through the top of the coupler to the tap.

The engaged coupler forms a seal such that CO2 from the gas line cannot enter directly into the beer line. The gas, typically pressurized at 12-14 PSI, increases the pressure inside the keg, forcing beer up the spear and out the top of the coupler towards to the tap. As the keg empties, the CO2 forced into the keg through the gas line on the side of the coupler occupies the resulting empty space in the keg. Every couple of weeks, the CO2 tank in our kegerator runs out of gas and requires replacement. Although some of the CO2 dispensed from the gas canister in the kegerator ends up dissolving in the beer, CO2 also occurs naturally in beer as a byproduct of the fermentation process. Thus, the head of foam at the top of a glass of freshly-poured beer has both natural and artificial components.


You may (or may not) recall that kegs of mass-produced American swill in frat house bathrooms have keg taps equipped with hand pumps. These decidedly low-brow beer dispensing systems introduce air into the keg, contaminating the beer and accelerating spoilage. Quality counts at Venture Café! Our craft beer selections remain unsullied by the surrounding environment until Amy, Greg, or Robin artfully pour them into squeaky clean, compostable Vegware cups. Stop by this Thursday from 3-8 pm to enjoy a cold beer, brought to you by Venture Café’s impressive collection of keg couplers.

Home brewing: a photographic journey

What could be a better St. Patrick’s weekend activity than brewing beer? I experienced my first taste of home brewing on Saturday, courtesy of my friend Tom, who acquired the relevant equipment and ingredients. The goal for the day was to make the recipe for a pale ale featuring citra hops. The first step was to mash malt that had already been run through a roller mill and crushed. The process of mashing combines the cracked grain with hot water, allowing enzymes to convert the starch in the malt into sugars. It’s like steeping tea.


Next, we added both liquid and dry malt extract. Some brewers favor an “all-grain” approach to brewing, wherein they essentially make their own extract and are able to exert more control over the brewing process. For beginners, however, buying ready-made extract is a nice shortcut because it saves time and requires less equipment.


The next step was to add the hops – both Nugget bittering hops and Citra flavoring hops. This phase of brewing requires occasional stirring with timed periods of heating at set temperatures between adding ingredients. We also added Irish Moss to prevent the beer from becoming cloudy.


Finally, it was time to take our concoction off the stove to cool it. The mixture has to be cooled to under 80 degrees so as not to kill the yeast when it is added. The cooling technique was quite low-tech: we gave the whole pot a cold bath.


Once our brew was sufficiently cool, we poured it into a sanitized container and added water up to the 5 gallon mark.


Tom took the initial gravity reading for the beer. Gravity refers to the density of the wort, which is largely dependent on its sugar content. Tom will double check the gravity of the beer before declaring the fermentation process complete, because a high reading could indicate that the yeast organisms have not yet finished their job – and the resulting beer will be too sweet.


After funneling the brew into its final (sanitized) storage container, Tom pitched the yeast.


The end result of my very first home brewing experience:


The tube and water bath serve as a low-tech but sanitary way of allowing release of carbon dioxide produced from the fermentation process, but preventing other gases or potential contaminants from entering the storage container. I was informed this morning that the yeast were happily eating and reproducing, as evidenced by bubbles in the water bath.

Hopefully, in about a week and a half, Tom and I will bottle a delicious beer.

What do ESB, APA, XPA, EPA, IPA and DIPA have in common?

We get frequent questions at the Venture Café bar about different beer styles, and because we serve a lot of ales, many inquiries revolve around distinguishing pale ales, American Pale Ales, Extra Pale Ales, and India Pale Ales. As more craft breweries develop their own versions of these styles, the boundaries between them become less defined and the labels less meaningful. However, I can provide a brief pale ale primer for what you might expect when you order one of these beers.

The pale ale is a style of beer made through warm fermentation processes with top-fermenting yeast and predominantly pale malts. (These characteristics differentiate it from lagers, which are cold-stored and incorporate bottom-fermenting yeasts.) The malts are the source of the light color.

The granddaddy of pale ales are the British bitters – Best Bitters, Special Bitters, and Extra Special Bitters (ESBs), which are distinguished by strength. These beers are usually amber in color and dry, with hop bitterness dominating the flavor profile. Goose Island Honker’s Ale and Young’s Bitter are both examples of this style.

American Pale Ales (APAs) derive from the Bitters. They too are amber in color but can also range to more golden palates. Compared to their English counterparts, they tend to be cleaner and have less body, with less of a caramel malt profile and a more hoppy finish. Most of the flavor comes from American hops, including Amarillo, Cascade, Centennial, Chinook, and Simcoe. Unlike Belgian beers, flavors from the yeast (esters and phenols that lend fruity or spicy notes to a beer) are weak and dominated by the hops. The alcohol content ranges from about 4.5-6%. Sierra Nevada Pale Ale is the quintessential example of this style.

Extra Pale Ales (EPA or XPA) are usually categorized under American Pale Ales. They tend to be lighter in taste and alcohol content than regular pale ales, but there are no hard and fast rules for the label. Both High and Mighty XPA and Berkshire Brewing Company Steel Rail Extra Pale Ale do indeed fall on the lighter side of the APA spectrum.

India Pale Ales (IPAs) represent a hoppy solution to keep British soldiers stationed in India happy. To prevent beer shipped to India from spoiling, 19th century English beermakers increased the hopping rate and the alcohol content. English IPAs are brewed with English hops and tend toward woodsy, earthy, and spicy flavors. Try Left Hand’s 400 lb Monkey or Brooklyn’s East India Pale Ale to get a taste for the English IPA. In comparison, American IPAs have more alcohol and are more aggressively hopped, so you can expect to experience a well-rounded hop aroma and a more bitter flavor. Some American IPAs incorporate resinous pine and bitter grapefruit flavors, but many feature an overwhelming flowery hoppiness. Compare Dogfish Head’s 60 Minute IPA or Mayflower IPA to the English style IPAs above.

Finally, Double IPAs (DIPAs) or Imperial IPAs are an American invention that goes to extremes. These beers usually use double or even triple the typical amount of hops in an IPA recipe, but also add more malts to balance the flavors. The result is often a deeper, more complex brew featuring hoppy notes alongside a well-rounded malt profile and a high ABV. I find these beers to be sweeter than the typical IPA as well. Harpoon Leviathan and Blue Hills Imperial Red IPA provide local examples of this style.

These short descriptions should arm you with some rules of thumb the next time the pressure is on to select a beer. But remember, at Venture Café, we are always happy to guide your choice, and you can rarely go wrong.


At Venture Café this past Thursday (7 March 2013), Robin and Shahin performed a wildly successful full-scale test of our new S-type keg coupler. Check out Operation KEG Part 1 for a blow-by-blow of the behind-the-scenes engineering. The first Eurobeer on tap at Venture Café: Leffe Belgian Blonde Ale. We dispensed an entire 30L pony keg in less than 90 minutes!

We captured the ceremonial tapping of the keg on video:

We had the distinct pleasure of serving an actual Belgian, Alban de Brouchoven de Bergeyck, who seemed quite pleased to encounter brew from his home country at Venture Café.


Operation KEG Part 3: Bespoke Kegbot


The Venture Café Kegerator Enhancement Group (VC-KEG) has been hard at work fulfilling its lofty mission to transform our kegerator into a technological marvel. As outlined in Operation KEG Part 2: Kegbot 101 the Kegbot open source beer kegerator control system has many virtues—most notably, the ability to measure keg temperature and beer consumption and to authenticate drinkers. Never satisfied to rest on his laurels though, Mr. Kegbot decided to take a trip to Savile Row and get himself a custom-made suit, hence the title of this post. Only the best for Venture Café! [Given that I have the artistic ability of a gnat, I commissioned my friend Ashley Short to render his new look in Photoshop.]

Why bother with the formal wear? For aesthetic reasons, of course. It’s perfectly understandable why the specifications for the Kegbot electronics call for old-school LEDs, resistors, capacitors, temperature sensors, and transistors with long wire leads. This choice of form factor makes self-assembly by hobbyists far easier. However, I just couldn’t get over the shocking resemblance of the Kegbot printed circuit boards (PCBs) to my 8th grade science project. I opted to redesign the PCBs with surface mount components, ensuring end products with sleeker, more sophisticated lines.


In a standard Kegbot build, an Arduino Uno acts as the primary controller. Arduino has done a great service to the world by bringing embedded computing to the masses. Arduinos are, for instance, immensely popular with hipsters creating ironic conceptual art installations that involve blinking LEDs. However, an Atmel Atmega328 8-bit microcontroller clocked at 16 MHz with no operating system has its limitations, prematurely thwarting VC-KEG’s Machiavellian scheme to rule the universe (of kegerators).

I considered two replacement options for the Arduino, both equipped with 32-bit ARM processors, the Raspberry Pi and the BeagleBone. Exhaustive feature comparisons live elsewhere on the Internet. The Raspberry Pi and required accessories retail for about ⅔ price of the $89 BeagleBone. The CPUs on both boards are clocked at upwards of 700 MHz, but the BeagleBone’s Texas Instruments AM335x ARM Cortex-A8 processor seriously outguns the Broadcom BCM2835 ARM11 on the Raspberry Pi.


Macho man microprocessor comparisons aside, the 65 externally accessible GPIO (General Purpose Input/Output) pins on the BeagleBone, make the Dog (woof!) the clear winner for the Venture Café Kegbot. The Raspberry Pi has a mere 8 GPIO pins, not enough to meet Kegbot requirements. (Ironically, Texas Instruments is one of my employer’s biggest competitors. But Analog Devices has no skin in this particular game, so as Robin Coxe, Venture Café bartender, I chose TI.)

The GPIO header connectors running along the edges of the BeagleBone enable the Kegbot Controller board to readily interface with the CPU. Mezzanine cards that mate with the BeagleBone to provide supplementary functionality such as the Kegbot Controller are called capes, in homage to the cape-wearing superhero beagle Underdog. Kegbot Controller inputs include temperature and flow readings from the Kegbot Coaster boards inside the kegerator. The processor can, in turn, activate relays, switch the LEDs on and off, and activate the buzzer over output lines. The BeagleBone sources 5V and 3.3 V DC power to the Controller board over the header connectors. Because the end result of my redesign of the Kegbot Controller to make it BeagleBone-compatible makes the entire get-up look like a flying squirrel, the Venture Café Kegboat Controller board shall henceforth be referred to as the BeagleBeer Flying Squirrel Controller.

As a self-respecting, card-carrying member of the Open Source Hardware Association, I forked the kegboard repository and uploaded the Venture Café Kegbot PCB design files and the Bill of Materials (BOM) to Github. I ordered the components on the BOM from Digikey, the mail-order electronics superstore in Thief River Falls, MN [of all places], and Sparkfun Electronics in Boulder, CO. [For those interested in building a standard Kegbot from scratch, click here and here for comprehensive parts lists.] I used Cadsoft Eagle PCB design software, originally developed in Germany, which has become the de facto standard for open source hardware designs. The arcane details of PCB design would probably bore most of you silly, but for those interested in learning more, the helpful engineers at Sparkfun have put together an excellent set of web tutorials on schematic capture, PCB layout , and parts creation using Eagle. The final PCB layouts of the Kegbot Coaster board and the BeagleBeer Flying Squirrel as rendered in the Eagle PCB layout tool:



I plan to retrieve the hand-assembled PCBs from the contract manufacturer, Proxy Manufacturing in Methuen, MA, by the end of the week. Just like our beer, Venture Café electronics are locally sourced and artisanal. (“Wicked awesome!” as we Massholes liked to say back in the ‘80s.) The PCBs were fabricated in the Oregon, so the bespoke Venture Café Kegbot electronics can wear the “Made in the USA” label with pride. As soon as I have fully populated boards in hand, I’ll port the Kegbot controller code (written in C++) from the Arduino to the BeagleBone, a process that, like most things in life, is easier said than done. Fasten your seatbelts! In Operation KEG Part 4, I’ll document the fascinating saga of commissioning the Kegboard Coaster and the BeagleBeer Controller electronics.