A Study on Beer Taste? Sign Me Up!

I saw this item from the Journal of Food Science posted by a friend on Facebook.

This study aimed to test the much-pronounced but poorly supported theory that “Guinness does not travel well.” A total of 4 researchers from 4 different countries of origin traveled around the world for 12 mo to collect data on the enjoyment of Guinness and related factors. The main outcome was measured on a Visual Analogue Scale (VAS) from 0 (enjoyed it not at all) to 100 (enjoyed it very much). A total of 103 tastings were recorded (42 in Ireland, 61 elsewhere) in 71 different pubs spread over 33 cities and 14 countries. The enjoyment of Guinness consumed in Ireland was rated higher (74 mm VAS) than outside Ireland (57 mm; P < 0.001). This difference remained statistically significant after adjusting for researcher, pub ambience, Guinness appearance, and the sensory measures mouthfeel, flavor, and aftertaste. This study is the first to provide scientific evidence that Guinness does not travel well and that the enjoyment of Guinness (for our group of nonexpert tasters) was higher when in Ireland. Results, however, are subject to further verification because of limitations in the study design.

This is a pretty fun bit of research though, as the authors point out, very limited. For example, there is no reporting on a "control" beer to see if their findings are Guinness specific. Strangely, the authors attempted to adjust for pub ambience (which was ranked higher in pubs in Ireland) but seemed to ignore the fact that while in Ireland they consumed more alcohol before testing than in other countries (2.5 versus 1.4, P = 0.035), a factor that can undoubtedly affect perception and overall enjoyment. The authors point out the fact that Guinness is brewed in nearly 50 countries around the world, so the question "Does Guinness travel well?" may not be appropriate. And of course expectations and blinding issues run rampant in a study like this. Clearly the authors should recruit my beer-drinking expertise the next time they embark on this type of research.

Other items of note: The price of a pint of Guinness was not significantly different in Ireland compared to the other countries visited (£3.66 versus £3.83) and none of the pints served in Ireland had the head stamped with a shamrock or other design, compared to 13.1% of non-Irish pours (P = 0.015)

I have to say that while journals often do publish short "fun" pieces, I was a bit surprised to see this study appear in a peer-reviewed journal instead of a blog post. I just hope the editors are as kind when I submit my upcoming study of the best local beers here in Ottawa.

2000 years old tetracyclin beer?

When tetracyclin was detected in large quantities in the bones of ancient Sudanese Nubians from 350-550 CE, many wondered if it was accidental. But evidence suggests that it was manufactured on purpose by growing streptomyces in beer. It seems to have been used therapeutically, including in children:

"“The bones of these ancient people were saturated with tetracycline, showing that they had been taking it for a long time,” he says. “I’m convinced that they had the science of fermentation under control and were purposely producing the drug.”

Even the tibia and skull belonging to a 4-year-old were full of tetracycline, suggesting that they were giving high doses to the child to try and cure him of illness, Nelson says."

Mosquito Beer Goggles

It's the time of year when people retreat to campsites and cottages to relax and enjoy a beer on the dock or by the campfire. The only real downside to those kinds of getaways is the bugs.

There are over 2500 different species of mosquito around the world, but sometimes it seems like they've all joined forces to suck us dry unless we arm ourselves with DEET or lasers. And that beer by the lake may not be helping.

A paper just published in PLoS ONE reports that beer drinking makes you more attractive to mosquitoes. (Now if only my beer drinking would make me more attractive to other people) Greg Laden has more.

Researchers working in Burkina Faso recently decided to test the hypothesis that beer drinking would have an effect on mosquito prey preference, and they found that it did. Twenty-five human volunteers drank beer and were explosed to 2,500 A. gambiae mosquitoes, and 18 volunteers drank only water and were exposed to 1,800 A. gambiae mosquitoes (100 mosquitoes per volunteer). The behavior of the mosquitoes was observed, and it was determined that they go after the beer-drinkers preferentially.

As mentioned in the quote, the particular mosquito species being studied was A. gambiae, one of about 40 species that transmit malaria, which is another reason to trade in the beer, perhaps for a gin and tonic.

There was also some speculation as to why beer drinking attracts the bugs. One suggestion is that it might be adaptive: because of impaired reflexes and co-ordination, a mosquito biting a drunk is more likely to survive the encounter.

Personally, I think they're attracted to the increased self-esteem.

Good Head

Go to the pub, and you'll undoubtedly find people gingerly pouring from a pitcher trying to minimize foam and acheive a headless beer. This despite the fact that many beer glasses, particularly special glasses for premium beers, have a volume marking that allows for half an inch or more of frothy goodness. Which way is better - thick head or no - is a matter of taste, quite literally.

Beer is a delicious glass of chemistry and biology, and the bubbles can be natural or artificial. For the most part, the bubble forming gas is carbon dioxide, which causes bigger bubbles and a 'fizzier' beer. CO₂ can be artificially introduced by dissolving it under pressure, or it can be naturally formed as a byproduct of fermentation by the yeast.
Some beers, like the Guinness family of brews, use nitrogen or a CO₂-nitrogen mix either as a widget in the pacakged product or to draw the liquid from a keg. These bubbles are smaller and result in a denser head, less effervescent beer and the distinctive 'creamy' texture. Even without foam, the gas involved influences a beer's flavour. Dissolved carbon dioxide forms the weak carbonic acid, affecting the acidity of beer and therefore its taste.

Obviously the bubbles at the top of the beer aren't just gas - there's something holding them together. Lasting bubble formation requires a surfactant, a molecule with both hydrophilic and hydrophobic parts, like the lipids in soap. Ironically, even trace amounts of soap residue in your beer glass can kill the head. As the gas bubbles in your beer rise, they pick up a number of molecules. One of the more important molecules is lipid transfer protein-1 (LTP1) (pictured). This protein is present in barley, but is not surface active until denatured by the boiling of the unfermented liquid (or wort). This protein is so important for foam stability - and foam stability is so important for the beer drinking experience - that German scientists (and who knows beer better than the Germans? The Czechs and the Irish, that's who) have engineered yeast expressing LTP1 to improve the foaminess of your draught. Potential brewmasters should also know that the temperature and duration of boiling your wort affects the extent and degree of LTP1 denaturation, and therefore the quality of your head. But LTP1 isn't the only molecule involved in a frothy mug, and not the only one subject to engineering. Japanese researchers have discovered that another barley protein, lipoxygenase-1 (LOX), has the opposite effect, reducing foam and flavour stability. LOX-less barley has been developed and tested for brewing by Sapporo.

So why go to all the trouble to increase the amount and stability of beer head - something many drinkers go out of their way to avoid? For one thing, a foamy pour reduces carbonation. This has two effects: First - and this is important to any drinker and the bartenders they're tipping - it means you can drink more. On average, a pint of beer contains 2.5 pints of carbon dioxide. A still pour keeps the CO₂ dissolved in the beverage, where it ends up in your stomach, contributing to a bloated feeling. Secondly, less dissolved CO₂ means a less acidic flavour. A bubbly pour releases the gas, affecting the taste. Acidity is also associated with a less thirst-quenching beer. Yes, research has been done into what factors determine how refreshing that beer is on a hot summer day. Strangely, while acidity - which can be caused by carbonation - along with foam and flavourfulness, negatively affect thirst-quenching properties, bubble density and carbonation have a positive correlation. Which is why your refreshing summer beer tends to be a fizzy, flavourless drink.

As the bubbles rise in your glass, they pick up more than just LTP1. Alpha-acids from the hops are also accumulated, and create a longer lasting foam. More importantly, these are also flavour compounds. Like wine - or just about anything - flavour is as much a play in the nose as on the palate. And while you won't find many beer drinkers discussing 'bouquet', it's there and it's important. The white cap in your glass concentrates these scents and flavours, enhancing the drinking experience.

Next time one of your friends gives you a foamless beer, ask them to pour it right. Not only is it visually appealing (and a clue that the beer you're drinking isn't flat) but it results in a more drinkable pint that engages your tactile, olfactory and gustatory senses. There's a lot of science in there too.

Drunk Red Asians

Recently went drinking with a FOB (friend of the bayblab) and, as usual with him, he turned pretty red in the face. Apparently approximately half of people of Asian decent have this reaction to the consumption of alcohol, which has been nicknamed the "Asian glow".This glow shows up really well in this particular FOB, because he is half Caucasian, providing a pale, pastey canvas for his inebriated glow.
I had heard that the Asian glow was the result of a variant or deficit of the acetaldehyde dehydrogenase (ALDH2) enzyme. This enzyme is responsible for the conversion of acetaldehyde into acetic acid. Acetaldehyde is the first breakdown product of ethanol produced by alcohol dehydrogenase and it is this nasty compound that causes all of the "Asain glow" symptoms which also include: nausea, headaches, light-headedness, an increased pulse, occasional extreme drowsiness, and occasional skin swelling and itchiness. It is also responsible for the scurge of mankind; the hangover.
Worse still for the previously mentioned FOB is that the east asian drunken red face variant of ALDH2 is associated with increased risk of alcoholism related cancer. This is likely because acetaldehyde is carcinogenic and would be in increased concentrations if you posses a less active ALDH2 enzyme.
If you're smart and paying attention you'd remember that the FOB is of both Asian and Caucasian decent. So what about his Caucasian allele? How could an enzyme deficiency be domninant? Well, the origonal paper on the subject explain demonstrates that ALDH2 exists as a homotetramer and that the Asian allele has a markedly reduced half-life and in a cell expressing both versions of the subunit passes on it's reduced stability to the resulting heterotetrameric complex. So presumably the increased acetaldehyde is not due to decreased specific activity of ALDH2 in some Asians but due to lower stability of the active enzyme complex. Therefore this allele is dominant.

Alcohol may impair your science

If you're a graduate student, chances are you came into the lab yesterday hungover from St Patrick's day and that your productivity was impaired. So how does drinking beer impact your science? The February issue of Oikos, an ecology journal, features a paper by Tomas Grim from the Czech Republic entitled "A possible role of social activity to explain differences in publication output among ecologists".

We at the bayblab take beer drinking and science very seriously, and these new findings are cause for concern. The study is mostly a correlation between beer consumption and citation counts. As per the abstract:

"One of the most frequent social activities in the world is drinking alcohol. In Europe, most alcohol is consumed as beer and, based on well known negative effects of alcohol consumption on cognitive performance, I predicted negative correlations between beer consumption and several measures of scientific performance. Using a survey from the Czech Republic, that has the highest per capita beer consumption rate in the world, I show that increasing per capita beer consumption is associated with lower numbers of papers, total citations, and citations per paper (a surrogate measure of paper quality)."

Unfortunately I do not have access to the paper in question to peruse the figures but here are some great quotes about the results from the NY Times:

“It’s rather devastating to be told we should drink less beer in order to increase our scientific performance,” Dr. Symonds said."

"Though the public may tend to think of scientists as exceedingly sober, scientific schmoozing is often beer-tinged, famous for producing spectacular breakthroughs and productive collaborations, countless papers having begun as scrawls on cocktail napkins."

"Yet the new study shows no indication that some level of moderate social beer drinking increases scientific productivity. "

"More important, as Dr. Grim pointed out, the study documents a correlation between beer drinking and scientific performance without explaining any correlation. That leaves open the possibility that it is not beer drinking that causes poor scientific performance, but just the opposite"

I think this needs to be investigated to find the optimal number of beers to produce good science. We'll get into this matter as soon as we've figured out the optimal number of beers for bowling... So what is your citation count and beer consumption?

Bayblab Podcast Episode 13

One year anniversary podcast: supersize edition (twice the length, half the content). Discussions of the appendix, the Ignobel, the cancer carnival, and the usual beer-fueled nonsense.

Bayblab podcast Episode9

Finally available in all its glory..an epic two part series.

Part1: Steven Hawking presents... glycolysis and the Warburg effect in cancer and heart attacks, and road density in the United States.

part2: Pharming drugs and the production of interferon in transgenic tobacco plants and opportunities from advances in sequencing technology such as mapping the beer genome...

Also if you want to subscribe to this podcast, simply search for bayblab at the iTunes store...