The final word on beer serving temperature.

Sounds a bit arrogant, eh? Well, follow along and we’ll see if you disagree.

It seems like every week I run across some sort of discussion about what temperature to drink your beer at. These conversations usually involve some people (who are often fairly well educated in the various topics of beer) enlightening the beer n00bs of the best way to serve, pour, and drink various beers. This “best way” is most often dependent on the style of beer in question, with lagers being served colder than ales and other ideas like that. Well, I’m here to tell you that is a bunch of bollocks.

Now, don’t get me wrong: everyone who drinks or eats anything should know that volatile flavor compounds are more readily released and detected when the sample is warmer. The same with agitation: when you stir, swirl, swish, or chew your sample (be it solid or liquid) you’re allowing more volatiles to be released. Also, controlling serving temperature has great importance when conducting sensory experiments, not only for ensuring that all samples are treated in the same way, but also to maximize (or whatever the goal is) the chance of picking up certain flavors. These are all fundamental ideas in flavor science.

But beyond these considerations, my point is that once you are armed with that knowledge you should be free to enjoy your food or beverage in whatever way you like most. There are a number of instances where a beer will taste better when it is colder than it does after it warms, regardless of the style. I’ve experienced this many times, particularly when drinking beers from small microbreweries who may not have the control of quality parameters that larger breweries have. Some beers will be wonderful and defect free when drank below 40F, but after the beer warms in your glass some of the ugly defects that you didn’t notice earlier start to come out. Diacetyl is usually the culprit here, but it can be other flavors as well. Plenty of times I’ve opened a can of Heineken and poured it into a frosty glass and enjoyed the first half, but by the time I near the end of the glass oxidation flavors are starting to make themselves apparent and the beer becomes far less tasty. In these cases you almost NEED to drink the beer cold, regardless of whether it is an ale or a lager, just to enjoy it. Another reason I enjoy my beer colder is that it’s more drinkable and refreshing, and yes, I often like my ales drinkable and refreshing. Sometimes when flavors hide behind the coldness it can make the beer easier to drink. For example, beers that have higher alcohol and a lot of solvent-like flavors can be tamed when drank colder, while they can sometimes get more aggressive and unpleasant as they warm.

What might bother me the most about this serving temperature topic is when a pub will assume that this is the best temperature at which to serve their beer. Sure, it may be better for delineating the subtleties of the beer flavor, but what are those extra 10 degrees doing to the stability of the beer? It’s allowing the beer to oxidize and age that much faster, so while you may be trying to appreciate the beer now you are also making a poorer quality beer for the next pint.

What it boils down to is this: don’t tell me how to enjoy my beer. I know how and when to use serving temperature to achieve different goals, but when I am drinking beer because I just want to drink a beer, I will serve it at the temperature that I want it at, not what you think it should be. And I encourage you all to have the same mind set: if you like your IPA at 35F, that is your call and I won’t ever have a problem with it. I just hope you’re not under the impression that all the flavor you taste is all the flavor there is in that beer.

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Teasing out the underlying aromas of complex flavors

One of the most interesting things about flavor science is the fact that certain aromas and flavors are so complex that no single compound can replicate the experience. Even flavors which are represented fairly well by a single compound (like the isoamyl acetate in bananas, or the methylanthranilate in concord grapes) are more of a simulacrum to their natural inspirations, often times having a slight “artificial” quality. While this “marquee” compound may make up the bulk of that particular flavor, there are probably a half-dozen or more other compounds at or below threshold levels which are contributing to the overall impression of the flavor, adding to its complexity and depth. In some cases, these compounds may have aromas in the same category as the main flavor, but sometimes they seem to come out of left-field…

Chocolate, maybe not surprisingly, is one of those flavors that is made up of a strange hodge-podge of flavor compounds which, taken on their own, have no relation or similarity to the flavor of chocolate. Research from the Technical University of Munich is starting to show just how complex chocolate flavors are. They’ve found that there are up to 600 different aromatic compounds in cocoa beans, but you really only need about 25 of them to make a decent chocolate flavor. Twenty-five is still a big number for a single flavor and the ones on that list come from a wide-range of flavor categories, many having no obvious connection to chocolate: potato chips, cooked meat, peaches, raw beef fat, cooked cabbage, human sweat, earth, cucumber, honey… etc etc. Certainly not the types of flavors you contemplate as that decadent Swiss chocolate melts in your mouth, are they?

While not part of the research mentioned in this latest press release (for an ACS meeting), here is a table from a book about ‘chocolate science’ which includes data from the same researcher (Schieberle) which shows a large list of compounds found in the aroma of chocolate (milk chocolate, pg 67; dark chocolate, pg. 69). Since chocolate also undergoes Maillard reactions and is fermented as well (like beer in both regards), a number of these flavors are also found in beer: maltol, phenylacetaldehyde, diacetyl, dimethyl trisulphide (ew!), gamma-nonalactone, butanoic acid, various furans and pyrazines, just to name a few. Fascinating stuff!

Esters

Yes yes, I know. You’re right: it’s been far too long since I’ve posted. Well, I’m going to try to make it up to you with a nice article about one of the most influential and ubiquitous flavor components of beer: esters. I bet you’ve been waiting a long time for this article.

So, what are esters? If you ask a chemist they’ll tell you that esters are a class of molecules which contain a specific type of functional group called an ester group, if you can imagine that. These ester groups are made up of an oxygen molecule double-bonded to a carbon which is immediately adjacent to another oxygen which is bonded in-line with the carbon chain of the organic molecule. Perhaps a picture would illustrate the concept well.

A generic ester.

Looking at that picture we see a portion of a larger molecule, where the R-groups represent what could essentially be any kind of organic chain. The ester group consists of the carbon and the two oxygens that are bound to it. Esters, due to the variation that can occur at those R-groups, are found in many shapes and sizes, but they all share the common feature of the ester group. The smaller weight esters are quite volatile and are frequently used in the production of food products and fragrances; they are largely responsible for much of the flavors and aromas associated with many types of fruits. Larger weight esters are also found everywhere, from DNA and plastics to triglycerides and explosives (nitroglycerin).

More after the break.

Taste vs. Flavor: A retronasal excursion

So, when we talk about what a food or drink “tastes like”, it’s pretty common to get confused about the terminology.  You may hear someone say that something tastes “fruity” or “rancid” or whatever.  What they are actually discussing is how the food smells.  As we discussed already, “taste” applies only to the basic tastes. Everything else, apart from the various tactile sensations, is aroma. Combine the taste, the aroma, and the mouthfeel and you’re now talking about the overall flavor of the substance.

Here’s an exercise for you to try to drive home this point:

Eat or drink something while your nose is plugged.  What I like to use is a piece of gum or a mint candy or something. It might be tricky to swallow like this, but it’s possible.  So while your nose is plugged, what are you sensing?  Sweetness, sourness, saltiness, bitterness, temperature, texture, etc.  It’s all just taste and mouthfeel, right?  No aroma.    Now, unplug your nose and breath out through it.  NOW we’re in flavor country, eh? This aroma that you smell while food or drink is in your mouth is called “retronasal aroma” (backwards nose). It is distinct from “orthonasal aroma” (straight nose) which is sensed when you put your face over the food and smell normally through the front of the nose.

So apparently, the majority of food and beverage flavor is perceived by your nose.  What’s happening is, as the substance is in your mouth, it’s warming up.  This warming action allows the volatile aroma compounds to leave the food and enter the air in your mouth and sinus.  Also, the surface area of the food is increasing as you chew it and spread it around your mouth, which also allows more volatilization of flavors.  Other things might be happening as well, like bursting carbonation bubbles carrying even more flavors out of the beverage.  All these things are causing aromas to become “airborne” which allows them to be carried into your sinus (via the back of the mouth/throat). This retronasal method leads to distinct differences in the aroma of your food compared to the orthonasal method, since with the orthonasal method the warming and the agitation of the sample are considerably less. It’s not uncommon for the flavor profile of a food or beverage smelled retronasally to be quite unique from the same product smelled orthonasally, as certain compounds may not be volatile enough in the glass to be detected; they may need to be warmed and agitated to be detected at above-threshold levels. This demonstrates the importance of smelling AND tasting the product before you try to describe it.

Here is a diagram showing a cross-section of the human head, where you can see how the back of the throat is connected to the back of the sinus cavity.  This is where the retronasal aromas access the olfactory bulb at the top of the sinus (essentially the bottom of the brain) which houses the various receptors responsible for detecting aromas.

Cross section of mouth and sinus, showing how retronasal aromas access olfactory bulb.

So now that we understand how taste, aroma, and flavor are all related, we can use the correct terminology when we discuss our sensations and assess our beers with proper diligence.