Author: Malcolm Frazer

Of the various things that can be wrong in a beer, one of the more difficult to nail down is astringency due to the fact it is a tactile sensation rather than a characteristic perceived by other senses such as taste and smell. Often and understandably confused with bitterness, astringency differs in that, by definition, it leads to the constricting of body tissue, which produces an autonomic puckering sensation, tightening of the jaw muscles, and/or a fuzziness on the tongue. The astringent responsible for these experiences in beer are polyphenols called tannins that exist in seeds, like barley, and vascular plants, like hops. They’re also present in hardwoods like those used to barrel age beer, in which case a minimal amount of astringency may be stylistically appropriate.

Generally, astringency is considered an undesirable trait in nearly every style and is occasionally cited as a reason for reduced scores by competition judges. Since tannin extraction is positively correlated with pH, brewers looking to avoid this characteristic are advised to adjust their mash using acid to ensure the pH stays within an appropriate range, the popular recommendation being 5.2 to 5.6, give or take. Astringency can also be caused by the heavy use of hops and has been noted to be more prevalent in highly dry hopped styles, making new products such as Cryo Hops all the more appealing.

With its similarities to bitterness, we were curious if tasters would be able to tell apart a beer intentionally dosed with astringent flavor standard from a unadulterated sample of the same beer and put it to the test!

| PURPOSE |

To evaluate the ability of blind tasters to distinguish between a pale lager dosed with astringent flavor standard from an unadulterated sample of the same beer.

| METHODS |

In order to keep me blind to the off-flavor for my own trials, all identifying labels were removed from the flavor standard packaging prior to me receiving them. Wanting to ensure the off-flavor had the best chance of being perceived, I relied on a technique I recently learned is commonly used in beer sensory analysis and made three 50/50 blends of Miller High Life and Miller Lite, dosing just one with with the flavor standard.

Since tannins are present to some degree in all beers and come from various sources, it’s difficult to define a threshold at which humans can typically perceive the astringency they impart. While FlavorActiv does not provide the specific threshold of their astringent flavor standard, they recommend dosing 1 liter of beer with 1 capsule in order to ensure a perceptible concentration. I prepared the dosed sample per the instructions provided by FlavorActiv by first gently pouring about 200 mL of beer into a pitcher, adding the contents of 2 flavor standard capsules, gently swirling, then adding an additional 1800 mL of beer to the vessel. The non-dosed samples were treated similarly to ensure no differences caused by anything other than the off-flavor.

| RESULTS |

Data for this xBmt was collected during a TRUB Homebrewers meeting being held at Voodoo Brewery. In total, 19 people with varying levels of experience, all blind to the variable, were served 1 sample of the beer intentionally dosed with astringent flavor standard and 2 samples of the clean beer in different colored opaque cups then instructed to select the unique sample. In order to reach statistical significance, 11 tasters (p<0.05) would have had to accurately identify the dosed sample, while only 6 (p=0.65) were capable of doing so. These results suggest participants in this xBmt were unable to reliably distinguish a beer intentionally dosed with astringent flavor standard from a clean sample of the same beer.

The 6 participants who correctly selected the unique sample in the triangle test were instructed to complete a brief set of additional questions comparing only the two different beers, still blind to the nature of the xBmt. First, they were asked to select the beer they thought was dosed with the off-flavor and 4 people chose correctly. Tasters were then asked to select from a list the off-flavor they thought the beer was dosed with. Not a single participant correctly identified astringent, 2 selected diacetyl, and 1 each chose oxidized, metallic, acetaldehyde, and chlorophenol.

My Impressions: Unaware of the off-flavor used in this xBmt until after data collection, I found the spiked sample particularly difficult to detect, though I was able to pick it out in a semi-blind triangle test. I got flummoxed when I detected no differences between the beers upon initially tasting them. I was eventually able to sense what I thought was a slightly sharper bitterness in one of the samples, which left me torn between astringency and bitterness. My final decision, a 50/50/90 semi-educated guess, was based on the fuzzy prickly sensation I experienced in my mouth upon my initial taste and swallow– astringency. This was not an easy choice, the difference was less obvious than I would have expected, and it’s possible I had a slight advantage since I’d been undergoing some sensory training in preparation for the Certified Cicerone exam.

| DISCUSSION |

Tannins are real, they are present in beer, and they do lead to astringency. That’s undeniable. However, the fact tasters in this xBmt could not reliably tell apart a beer intentionally dosed with astringent flavor standard from a clean sample calls into question just how good us humans are at accurately detecting astringency. Considering the non-significant results from a recent xBmt on high mash pH, which is perhaps the most commonly cited culprit of astringency in beer, it seems plausible this oft noted foible is occasionally mistaken for something else. And what about beers made relying on the decoction method where portions of the mash are literally boiled? Contrarily, these beers are usually lauded for being generally smooth in character.

Another source of astringency is hops, particularly when they include high amounts of leaf and stem material, and I certainly feel like I’ve noticed a tannic bite when tasting a beer soon after adding a large dry hop charge. It’s not good, but it always seems to fade, which again leads me to question the accuracy of judges who claim to perceive astringency in an otherwise fine beer that hasn’t been aged on wood.

As a judge of many years, I’ve made my fair share of checks in the astringency box on scoresheets, and while I’ve tended to avoid it lately, I can’t help but question the veracity of those earlier evaluations. Astringency being a sensory perception, there really isn’t a good way to objectively measure its presence in beer, and given the aforementioned results, I’m not sure it’s as common as I’ve been led to believe, which leaves me feeling a lot less anxious.

If you have any thoughts about this xBmt, don’t hesitate to share them in the comments section below!

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