Thursday, September 19, 2013

BeerQuest: Off-Flavor tasting at Blank Slate Brewery.

On a lazy Sunday evening, I got up off my couch and drove across Interstate 275 into Ohio, crossing the river. After a short 20 minutes of breeze and riverside driving, I found myself browsing through the equipment at a brewery, admiring the handiwork of one man and many hours of labor. I wasn't there to drink beer or learn brewing, however; I had come for something much more sinister.

It was Blank Slate Brewing Company I wandered around, waiting for more attendees to that night's event. I admired the close quarters and warm notes of grain in the air, noting the unique touches of Scott LaFollette's mind. Fermenters named after the Three Stooges and an A-frame ladder painted to look like an American flag are just two of the many quirks around Scott's brewhouse. A jungle of steel and carbohydrates in a storage unit, Blank Slate's site is a refreshing change from most of the breweries around town. It almost feels like home.

One of Blank Slate's fermenters, named after the curly-haired member of the Three Stooges. The other ones are easy to guess. I'm glad Scott didn't name the third fermenter "Shemp."

I, however, was not there to admire Blank Slate's brewhouse. No, I had attended at the behest of Lindsay Bohanske (@BeerNFoodLover) of Love Beer, Love Food. Lindsay is studying to be a certified Cicerone, and in her dealings with Scott (Who is a certified Cicerone) had discussed an off-flavor beer tasting panel for local bloggers and personalities. Scott, who is always welcoming, gladly jumped at the chance.

For those not familiar, beers, like most other alcoholic beverages, can develop strange flavor characteristics referred to as "off flavors." When someone says "This tastes off," they've probably discovered an off flavor. These flavors can vary from innocuous ones like acetaldehyde (A mild sweet, sometimes apple-tasting note) to brew ruiners like skunking (Tastes exactly what it sounds like). The purpose of a tasting panel such as this is to train a taster's palate to recognize these flavors. While the actual off-flavors usually reside in a much more subdued version in commercial beers, they can still be there, and knowing what to taste is valuable information.

Barrels, surely aging something magical.
After Lindsay and her husband Mike, along with their friends Sean and Becky, sat down at a table Scott had prepared, our gracious host vanished into his vast cooler to prepare the samples. We pored over our tasting sheets, committing the off flavors' descriptions to mind or paper with notes. Wisely, Scott chose not to start us out with the control, but with an off flavor to trick our taste buds.

First up was acetaldehyde, the flavor I brought up earlier. It's marked by slight sweetness and sometimes a green apple flavor. While sweetness isn't always an undesired flavor in beer, the apple flavor is a tell-tale sign of stressed yeast. When too little yeast is pitched, the little critters have to work overtime to ferment the beer. Eventually, the acetaldehyde in the beer will convert to alcohol, so usually these flavors can be counteracted by a longer bottle conditioning.

Untouched, unmolested Bud Light Platinum. You finally did something useful for me, AB-InBev!
What was perhaps much more interesting that identifying the flavor was Scott's disclosure of the source: Unadulterated Bud Light Platinum. The sweetness in the beer probably comes from yeast trying to ferment up to 6 percent alcohol in a beer that in homebrew conditions, wouldn't exceed 3 percent. I would later find out from Jim Matt (@jemthebrewer), head brewer at Rhinegeist Brewery, that the flavor we tasted was not actual acetaldehyde, but ethyl acetate. Regardless of the taint, it was a good representation of the off flavor.

Our second beer wasn't exactly easy to guess. All of us smelled and tasted, smelled and tasted over and over again and couldn't pick up the flavor. Only after being asked to cover our eyes and a bit more work on the part of Scott did we pick up the flavor. What a flavor it was. Beer isn't supposed to smell like buttered popcorn. Lindsay and I, after picking up the smell, couldn't even bring ourselves to ingest the stuff. The second off flavor, diacetyl, makes itself known in a buttery smell and flavor with a slickness on the tongue. Usually, lack of oxygen in the wort pre-yeast pitching can cause this one. Scott told us some people can't taste diacetyl, and he wasn't wrong. Only Lindsay and I even picked up on the flavor.

The third sample was oxidized. Scott did this fairly easily by pouring the beer into a new bottle, only filling about halfway, then capping it. He turned it on its side and let it hang out for several days at room temperature. Since the bottle hadn't been purged of oxygen before filling, it reacted with the beer, giving it the stale, old papery flavor of an oxidized beer. Too much contact with air and splashing of the fermented beer during transfer and bottling will give this flavor.

Our fourth sample was our control. The original "King of Beers," Budweiser. Sadly, it wasn't in one of their new fancy "Here is less beer for the same price" bow tie cans. Even though it wasn't tainted, it still tasted depressingly bad. You can't polish a turd, I suppose.

Moving on, the next sample had some not-so-delicious notes of corn going on. The vegetal aroma wafting from our next sample of beer was a prime example of dimethyl sulfide (DMS), a compound that manifests its nefarious tentacles in beers that aren't properly boiled. Wort that doesn't sit at a rolling boil for long enough will hold onto these compounds instead of boiling them off.

Sadly, we had to move on to another off flavor after this, continuing with my mother's old favorite brew, Corona Extra. I say sadly because anyone who's tasted a Corona knows why there is always a lime to be found in the neck of the bottle: It's skunked. Corona, which comes in a clear bottle (What is wrong with the world), is skunked before it even hits shelves. The lime dulls that flavor. Aside from the fact that beer doesn't need fruit to taste good, it masks the true sinister character of Corona. Scott did us one better: He sat the 24-ounce bottle of Corona out in the sun for a few hours, really cranking up the musk in the beer. I didn't even have to taste the beer to catch that skunky aroma. To say it was disgusting is an understatement, and glutton for punishment that I am, I actually took a sip of the liquid. There's a pretty great picture over in Lindsay's post of my reaction.

You know, it was skunked already, Scott. You didn't have to leave it in the sun a few more hours. I can almost smell this beer as I type this.

Our second to last sample featured the fusel, or alcohol characteristic. Sometimes a person may say a beer is "hot." This usually means a high-gravity beer hasn't conditioned for long enough. Beers with this characteristic will usually burn a bit and cause a warming sensation in the throat, and have a bit of a sharp, ethanol-heavy aroma. Scott easily set this up by dumping a shot of grain alcohol in the sample before rationing it out.

We finished up with an acetic, sour sample. Sometimes, sourness is a desired characteristic in beers. Some of the best beers I've ever tasted are sours, but typically sourness is a flavor reserved for wild and sour mashed ales. It's marked by a sharp, tangy aroma (Think balsamic vinegar) and a sourness that really hits the back of the tongue. As I said, it can be desired in some styles, but Scott explained to us that sourness in a non-sour beer can be a symptom of dirty beer lines. He also explained that a lot of bars don't clean their beer lines regularly enough, which scared me a lot. A bit of plain white vinegar in the sample provided the sourness needed, but I honestly thought it improved the Bud. Word to the wise: a few drops of vinegar in a can of Budweiser makes it mildly drinkable.

After all that grossness, Scott thankfully freshened us up with a collaboration beer as part of the 2012 Oktobersbest competition put on by Cincinnati Malt Infusers. Brewed by Tom Frank of Erie, PA, the beer is called Flagship City Mild. A classic English mild, it reminded me of a cross between Fuller's ESB and Rhinegeist's Uncle. Scott offered me a refill and by instinct I politely declined. That may have been one of my lowest moments, refusing free, delicious craft beer.

Flagship City Mild. Tasty and needed on a warm day.
The tasting was a bit of an eye opener. I feel like I'm better equipped to catch problems in beers going forward, and I know it'll help with my homebrewing escapades. I'm grateful to Lindsay for working to organize this event and her husband Mike for taking some great photos that you can see in Lindsay's post. Last, but certainly not least, thanks to Scott for having us in and sharing his knowledge (and beer)! Attending the tasting has me excited to set up my own with some friends who have been eager to expand their beer knowledge.


  1. Hey, thanks for posting this. I've never noted the buttery flavour before!

    I was wondering if you could comment on "soy sauce" off flavours. I had a cask version of Fuller's London Porter recently, one of my favourites. It tasted horrible at this bar. It tasted heavily of soy sauce or oysters, instead of the full-bodied roastiness I'm used to.

    Similarly, I've had a bottle of Ayinger Celebrator that tasted like vegemite, straight out of the bottle.

    What causes this off flavour? How can it be avoided?

    1. Thanks! Glad you enjoyed the article. While we didn't cover all of the possible beer off flavors in the tasting panel, I know what you are tasting.

      Soy sauce and vegemite flavors are symptomatic of autolysis. Yeast that is left alone for too long with nothing to eat and ferment will eat itself. The yeast cells will rupture releasing these flavors.

      For home brewers, this can be fixed by just making sure to use a secondary fermenter when it comes to beers that need to condition longer. In the case of the two beers you had, they were probably on the shelf too long, or the brewer left too much yeast in solution. Both of those beers are bottle conditioned (as are most European beers), and eventually the bit of yeast in the beer that was put there to produce fizz started eating itself.

  2. Ian,

    Enjoyed the article. I never get a chance to check out your site often enough. Learned a lot though.