quiz 2.4

Sensory Aspects of Beer Consumption

1 http://beersmith.com/blog/2012/04/10/dimethyl-sulfides-dms-in-home-brewed-beer/

2 http://www.picobrewery.com/askarchive/dms.htm

4 http://www.bjcp.org/

Do you think you know what it takes to have a good beer? Well, you probably do. Human senses are extremely acute

and discriminating due to millions of years of evolutionary pressure. The difficult part about sensory analysis is

explaining the causes of flavor and aroma.

The sensory impact of beer is generally dominated by hops, malt, and yeast, but other factors can play a crucial role

(both good and bad) in flavor. Descriptions of beer flavors appear to be arbitrary, but they are actually precise and

accepted terms. The “beer wheel” below shows off some of these terms:

The 3 largest slices in the wheel (not counting mouthfeel) are all due to the influence of malt, hops and yeast. Sugar

(added), alcohol, barrel aging, and chemical flavors round out the list.

Malt sensory impact

Malt is responsible for cereal flavors, malt sugar flavors, and roasted flavors in beer. Cereal flavors are related by terms

such as grainy, cracker, and bready. Sugar flavors are related by the words sweet and caramel. Roasted flavors are

coffee, roast, toast, toffee, nutty. As mentioned previously, the prevalence of malt flavors in a beer are mostly the result

of style and nationality (Americanized beers have a smaller malt impact than their European counterparts). While malt

flavors are expected in beer, one must keep in mind that malt should be in some sort of balance with hops and yeast.

Besides being out-of-balance, malt could also have specific problems, causing faults (not the worst mistakes) or flaws

(mistakes that render a beer unenjoyable/undrinkable).

Creamed Corn Beer?!

Have you ever had a beer that tasted like creamed corn or cabbage? What you’re probably tasting is a compound

called dimethyl sulfide (DMS). DMS is created (from an amino acid derivative called S-methylmethionine) during

malting and driven out by heat. Flavors due to DMS are caused by insufficient heat treatments during brewing (i.e.

poorly processed malt). DMS is considered a serious fault in beer, but it can be controlled by boiling the wort for a

sufficient amount of time. Here’re a few interesting tidbits about DMS 1 :

- DMS is found primarily in lagers, especially in adjunct lagers. The reason why is that corn is a big DMS

producer. You’d be more likely to find DMS in beers such as Miller Lite and Budweiser.

- DMS aromas stick around until after fermentation, so if you’re homebrewing, don’t toss a batch that smells

like it contains DMS

- Longer kettle boils can get rid of more DMS, so often it’s a good idea to boil lagers for 90 minutes

DMS concentration as a function of time into boiling and fermentation

2

Hops sensory impact

Hops, along with malt, are significant in determining beer flavor and aroma. Hops impart humic flavors (earthy, grassy,

floral, perfume), spiciness (spicy, minty, citrus, grapefruit, resinous, piney), and bitterness to beer. The bitterness and

spiciness imparted by hops are the most important flavors that many look for in hops, so they are often remarked on

most often. In the US, hops are of paramount concern, making them the most significant contributors of flavor and

aroma.

A primary use of hops is as a bittering agent. Bitterness is measured by, among other things, the amount of alpha acids

in beer. This translates into comparative values called International Bitterness Units (IBUs). More IBUs (up to just over

100) mean higher bitterness. The amount of bitterness depends on the style, as shown below:

Here’s how specific beers rate in IBUs:

Most problems concerning hops in beer center on using too much or too little as appropriate for a specific style. There

are other problems, though:

Yeast sensory impact

Of the 3 main flavor contributors, yeast often provides the smallest flavor impact. Yeast imparts fruity flavors (and

aromas) (banana, apricot cherry, vinous, spicy, pepper, clove) and acidic flavors (sour, acidic, barnyard, horse blanket,

leather, goaty, wet hay). Fruity/spicy flavors are often sought after. Acidic flavors are good only in specific beers

(Belgian sour ales) and are considered faults when present in other styles. Here’s a few flavors attributable to yeast

errors:

Tastes Like Summer Chores?

A refreshing beer after a hot summer’s day of mowing your lawn is an enjoyable thing, but you probably wouldn’t like it if

your beer smelled like you threw grass clippings into it. A compound called cis-3-hexanol (and several compounds like it) is

responsible for a musty or freshly-cut grass flavor in beer. This is normally not a bad thing, but excessive grassiness in beer

could be a problem. Hops usually impart this flavor/aroma to beer, so it’s best to use good quality (i.e. fresh) hops and not

to overuse them.

Pucker up!

Astringent is the word you’re looking for when you describe a food or beverage that causes your mouth to dry out and

pucker up. Astringency, which isn’t really a flavor per se, is most often caused by excessive tannins. Tannins are common

in most plants as a major compound located in the stems and seeds of plants. In beer, astringency can be reduced by

using less hops as well as treating grain more gently during milling and mashing (in order to avoid freeing up tannins from

seed husks). It’s also a good idea to avoid using fruit skins when making specialty ales/lagers and the like.

Types of tannins

Other sensory impacts

Additional flavors in beer are seldom an intentional thing. What’s worse is that some are considered serious flaws.

Here’s a few:

Medicinal

 Tastes like – cough syrup, cloves, bandaids

 Causes – naturally occurring in yeast (some more than others), contamination with wild yeast

 How to avoid – use the appropriate yeast for the style of beer being brewed, practice aseptic technique

Oxidation

 Tastes like – wet cardboard, sherry, stale

 Causes – excessive oxygen introduced to beer after fermentation

 How to avoid – prevent splashing while transferring beer from one vessel to another

Fresh Green Apples?

“Sick” yeast often results in incomplete fermentation and the production of flavors in beer reminiscent of freshly-cut

green apples. Excessive acetaldehyde causes those flavors, and aldehyde is produced as an intermediate compound in

alcohol fermentation. The solution? Let your beer ferment and age longer. Also, make sure your yeast is healthy and

growing.

Buttery Beer?

Diacetly is a compound which imparts buttery, sometimes spoiled butter, flavors to beer. Yeast typically produce, then

reabsorb diacetyl. Provided the yeast is healthy, there’s no problem. If your yeast is not healthy, you might be in for a

buttery flavor and slick mouthfeel that isn’t all as pleasant as it sounds.

The production and absorption of diacetyl from acetolactate

Skunky

 Tastes like – aroma of skunk, burned rubber

 Causes – exposure of alpha acids in hops to UV light

 How to avoid – avoid using clear or green brewing vessels in direct light

Solvent

 Tastes like – paint thinner, nail polish remover

 Causes – combination of very high fermentation temperatures and oxidation

 How to avoid – avoid high temperature fermentations and oxidation

Sulfur/Hydrogen Sulfide

 Tastes like – burning match, rotten egg

 Causes – hydrogen sulfide naturally produced by yeast

 How to avoid – ensure that beer is conditioned as CO2 carries off hydrogen sulfide

Sour/Acidic

 Tastes like – vinegar, acrid

 Causes – bacterial or wild yeast contamination

 How to avoid – sanitize!

Beer tasting

Judging the character of a beer involves much more than its taste. Everything from how it looks to how it smells is

important to a beer. Beer is typically judged on the basis of appearance, aroma, taste, and mouthfeel.

Appearance

Appearance is not just about the beer color, it’s about the head too. A clear, clean glass is really all that is needed to

judge color. Judging head requires that you use a specific glass designed to show off the head properties in the beer.

Here are some basic glasses:

In most cases, a pint glass is sufficient, provided it has sufficient volume (20 oz. is best). The larger volume of imperial

pints is good for properly dispensing European beers, which occasionally come in volumes larger than 12 oz. Pilsner and

weisen glasses are great for lagers and wheat beers because the narrower glass diameter helps to emphasize the head.

Tulip glasses are good for accommodating the voluminous heads of Belgian bottle-conditioned beers as well as providing

a larger liquid surface area to help you sense aromatics. A snifter is strictly for very high (usually above 12% ABV)

alcohol beers and also for lambics. High alcohol beers have no appreciable head, which is mostly due to the high alcohol

disrupting bubble nucleation (formation). Snifters allow the drinker to enjoy aromatics (because of the wide bowl) and

see “legs” (which are surface tension phenomena found in high ABV beverages).

Pouring a beer is both an art and science. The idea behind a good pour is 2-fold:

- Prevent overflow - Accentuate head

These two ideas are often in opposition to each other. Therefore, a good pour often involves a bit of compromise. A

standard type of pour is displayed below:

The exact pouring method you “should” use is sometimes dependent on the beer style. Some of the Belgian beers, for

instance, include pouring instructions. Some companies even advise or include glasses for specific beers!

Beer color is actually more of a science than a guessing game. Beer color is often quantified by SRM, EBC or Lovibond

units. SRM units (which are measured by a machine called a spectrophotometer) are the most common units in use, but

the other 2 units are well-used. Beer color is primarily caused by the level of kilning. Like in baking bread, the longer

malt is kilned, the darker it becomes. The reason for this is because dark non-enzymatic browning compounds are

produced the longer the malt (which contains sugar and protein, 2 things necessary for dark color formation) is kilned.

Below is how SRM units translate to styles and colors:

Beer head is a bit simpler in many ways than color. In heads, longer-lasting heads with smaller bubbles are prized as

evidence of good brewing. A longer lasting head is made more stable by smaller bubbles. Head is important because it

helps to preserve aromatic compounds responsible for flavors that are found in the liquid. Smaller bubbles are also

more apt to leave foam remnants (called “lacing”) on the sides of the glass. Lacing is an informal indicator of foam

stability in beer as well as being an indicator of a sufficiently-clean glass (lacing is hindered in dirty glasses).

There are a few rules-of-thumb with heads:

- High alcohol beers have little head - Beers made with wheat, rye, or oatmeal will have creamy/fluffy heads due to the protein content in these grains

Aroma

Aromatic compounds are volatile, which means they convert to gas phase easily. Pouring is a good way to release the

aromatic compounds, which are part of the malt (largest aroma contributor), hops (2 nd

), and yeast (distant 3 rd

). When

judging aroma, the relative intensity and quality of malt, hops, and yeast can be noted. In some cases, you can learn as

much about a beer by its smell than you can by its taste.

Taste

Taste is most often regarded as the most important aspect of enjoying beer. When tasting beer, there are a couple of

things to be aware of:

- Cold temperatures mask many flavors. Allow the beer to warm in your mouth before swallowing. - Different tastes are interpreted in different areas of the tongue, so, once again, pause before swallowing. - The aftertaste (or “finish”) is as important in beer as the initial taste.

SRM

An effective tasting does not necessarily involve drinking beer at room temperature, which many people incorrectly

assume you should do for dark English beers. The darkest beers are often consumed no higher than 61 degrees

Fahrenheit, which is cooler than room temperature (typically 68.0 to 74.3 °F). Lighter beers are best consumed at lower

temperatures, and temperatures near or below freezing are not good for any beer. The reason is that cold

temperatures impair taste bud function.

Frosting your glass by putting it in a freezer before use is an excellent way to dull your taste buds. You should really only

frost your glass if you are not drinking a beer for its taste.

Mouthfeel

Mouthfeel is literally, how the beer feels in your mouth. It’s not really taste because you are not using your taste buds

to detect anything related to mouthfeel. Experiencing mouthfeel is as simple as pausing before swallowing. There are a

few details that fall under the umbrella of mouthfeel:

- Body – light or heavy, how “thick” or “thin” a beer feels - Carbonation - fizziness - Creaminess – affected by the type of malt used, also affected by the addition of other ingredients (like lactose) - Astringency – a puckering sensation, usually caused by poor brewing but can also be caused by excessive hops or

overuse of dark roasted malts -

Aftertaste

Aftertaste (i.e. finish) is often cause by hops. Bitterness is the taste that is most attributed to aftertaste.

Judging Beer

Fancy yourself a cervesa connoisseur? While enthusiasm and trying all the craft beers you can think of may seem like good

preparation to be a judge, many competitions either prefer or require judges to produce some sort of certification. One of

the most widely-used programs is the Beer Judge Certification Program (BJCP). The purpose of the program is to 4 :

 Encourage knowledge, understanding, and appreciation of the world's diverse beer, mead, and cider styles;

 Promote, recognize, and advance beer, mead, and cider tasting, evaluation, and communication skills; and

 Develop standardized tools, methods, and processes for the structured evaluation, ranking and feedback of beer, mead, and cider

There’s several stages of training (Recognized, Certified, National, Master, and Grand Master), and your rank is dependent

on your exam scores (real and tasting) as well as experience judging. For more information, check out http://www.bjcp.org/

A more “prestigious” (and more expensive) route is the get certification as a “Certified Cicerone”. The Cicerone certification

program includes classes and exams designed to expand and test your beer knowledge. There are only 3 levels here,

Certified Beer Server, Certified Cicerone, Advanced Cicerone, and Master Cicerone. There are currently only 13 Master

Cicerones in the world, so that should give you an idea of the amount of effort you need to put into it. For more information,

and to check out your beer knowledge, try out http://cicerone.org/