Friday, December 19, 2014

The Chemistry of Christmas


What are the sights, the sounds, the smells, and the textures that you associate with Christmas? Perhaps it is Christmas trees with their lovely green shape, color and wonderful pine smell. Maybe it’s the smells of cooking, the savory smells of turkey or the sweet smell of warm cookies. Or what about all of the cozy feelings you get with big sweaters or a roaring fire? Did you know that there is a lot of chemistry that goes into all of the senses we associate with this holiday?

I was browsing through holiday-related articles, looking for something different from the usual psychology or sociology centered holiday study. That’s when I came across an article from 2012 published in the Journal of Chemical Education about the five senses of Christmas chemistry. The authors look through the lens of organic chemistry and take five “Christmas compounds” to examine in the context of the five senses.

Sound: Silver Fulminate

English CrackersIn 1824, Justus Liebig correctly determined the molecular formula of silver fulminate (AgCNO), and, around the same time, Friedrich Wohler identified the molecular formula for silver cyanate (AgOCN). Now, these might look the same, but they are in fact very different. Soon after, these scientists collaborated and rationalized these differences by introducing the notion of isomerism – molecules that have the same kinds of atoms but because these atoms have different arrangements in shape they differ in their chemical and physical properties. Silver fulminate is highly unstable, and even a small amount of friction leads to its violent decomposition. That makes it very useful when you want to make things go boom.

Christmas crackers are items that are a more traditional favorite in the UK. The Christmas crackers used today are short cardboard tubes wrapped in colorful paper. When they are pulled – bang! – out comes a colorful hat (usually looking like a crown), a small toy or a joke. The sound is made from the rapid breakdown of silver fulminate present in small quantities in the paper. Two thin strips of cardboard are glued together, one containing silver fulminate and the other a rough surface. When the cracker is pulled, the surfaces rub together to produce friction and facilitate the reaction. The compound goes through a redox reaction followed by a release of nitrogen gas and carbon monoxide. This sudden production of gases is what produces the distinctive popping sounds.

Sight: α-pinene

Different varieties of real Christmas treesA beautifully lit and decorated Christmas tree is one of the most common sights of this holiday. For the purposes of this section, we’ll assume that you bought a real tree rather than an artificial one. Geographic region can play a big part in the species of tree that is available to you, but they are very likely all evergreens (fir, spruce, pine, and cedars). In their resin, these conifers release terpene hydrocarbons, specifically monoterpenoids that is composed of two isoprene building blocks. This word should sound familiar as it is a derivative of turpentine, which you may know for its distinctive pine scent. Pine oil contains two monoterpenoids, α-pinene and β-pinene, which are both liquid at room temperature. This is another case of isomerism; although both have the typical C10H16 molecular formula there are four stereoisomers of each where the bonded atoms differing in their 3-D orientations. α-pinene is one of the most common volatiles in nature and is directly linked to the Christmas tree’s smell.

Touch: Sodium Acetate 

I don’t live in what most people would term a cold climate. Sure, we get cold weather, but we’re not talking blizzards. However, in my days as a field ecologist I spent many a winter day outside taking measurements. On those days, I was ever-so-grateful for one little invention: the hand warmer. Squish around the contents of the packet to get it to heat up to keep you pockets, and hands, toasty all day long. Bliss.

Many hand warmers are based on a simple chemical reaction – the crystallization of a supersaturated sodium acetate solution. When you squish around the contents of the hand warmer, you are triggering a chemical process. A nucleation site, usually a metal disk with small seed crystals, causes rapid crystallization of the super saturated solution. This is a highly exothermic process that releases energy to its surroundings as heat. These types of hand warmers are often reusable because of their physical mode of action. Other hand warmers rely on the exothermic oxidation of iron when exposed to air. Activated charcoal is used to catalyze the reaction, along with vermiculite and salt as additives. However, this chemical mode of action means that these are one use only products.

Taste: Tryptophan

/If you are a fan of a big turkey dinner then you have probably heard of tryptophan. It is a common misconception that the tryptophan from your turkey binge brings on sleepiness. It’s true that tryptophan is involved in sleep and mood control. However, turkey doesn’t contain enough of the compound (only 350 mg per 115 g) to have a soporific effect. It’s more likely that the sheer volume of food that you eat (and probably the wine you drank with it) on these occasions decreases blood flow and oxygenation, inducing the drowsiness.

Tryptophan is an essential aromatic amino acid that is commonly found in proteins. This compound has two enantiomers, chiral molecules that are mirror images of one another (kinda like left and right hands). L-tryptophan exists in nature and has a pronounced bitter taste, while D-tryptophan is synthetic and has a very sweet taste. Once you consume tryptophan, it goes through a series of metabolic reactions, one of which ends with melatonin. This final product is a neurohormone that is naturally secreted by the pineal gland, is involved in regulating circadian rhythms and may also have strong antioxidant effects.

Smell: Gingerol

Gingersnap cookies and gingerbread houses are common sights around the holidays, and with them come their wonderful ginger scent. Ginger products usually contain fresh or powdered bits from the rhizomes (rootstalk, or modified underground stem) of the ginger plant (Zingiber officinale). One of the organic compounds produced by this plant is gingerol, an aromatic vanilloid compound containing a β-hydroxyketone functionality. Interestingly, the taste of this compound can be modified via laboratory synthesis. Shogaol is derived by either refluxing gingerol with concentrated sulfuric acid or allowing a dehydration reaction can occur on gingerol to give the aldol condensation product. Shogaol has a more pungent flavor than gingerol. Conversely, ginergol can completely break down into zingerone after refluxing in strong aqueous base. Zingerone is considered to have less pungency than gingerol.

Considering this chemistry, you can alter the flavor of the ginger you use in your cooking. For example, if you cook ginger extensively, particularly in the absence of acid, then you produce the mildest tasting vanilloids, zingerone. But also keep in mind that your kitchen conditions are not laboratory conditions. This means that you are likely to end up with a mixture of all three compounds in your cookies.


That’s all for our journey through the senses of Christmas. If you are a chemistry teacher, or simply a chemistry nut, then I recommend reading through the paper. It has all sorts of skeletal formulas that you’ll love.


ResearchBlogging.orgJackson, D., & Dicks, A. (2012). The Five Senses of Christmas Chemistry Journal of Chemical Education, 89 (10), 1267-1273 DOI: 10.1021/ed300231z


p.s. In the interest of equal opportunity holiday science, does anyone recommend a study on Hanukka, Kwanzaa, etc. My academic database search is coming up with nil.



(images via Science NotesOld English Crackers, Buzzle, ThinkGeek, NYTimes Blogs, spydersen, respectively)

Thursday, December 18, 2014

Monday, December 15, 2014

Friday, December 12, 2014

The White Elephant in the Room: The Gift of Subversion

White Elephant Gift Exchange

Ah, the holiday work party. Free food, spending time with people you spend your whole day with already, and enough boozy libations to make things a bit more interesting. Here in North America, many workplaces engage in the gift “game” called the White Elephant Gift Exchange. On this topic, I'm basing today’s post on an article that I recently came across by Gretchen Herrmann in The Journal of Popular Culture where she dissects the Machiavellian nature of this little holiday game.

The White Elephant Gift Exchange (that I’ll abbreviate to WEGE, which you are free to pronounce as ‘wedgie’ even though no one does) is a pastime aimed to upend our normal conventions and beliefs of holiday generosity by celebrating and subverting the materialism. The goal is an unleashing of entertainment and satire, made all that much better after the first glass or two of eggnog.

I've written before on the topic of the perfect gift, concluding that considering someone’s interests and getting them something that you know they will love and use is the way to go. Herrmann generally agrees on this conclusion, pointing out that the ideal gift is a special item that is imbued with personal sentiment. This special item carries with it an emotional attachment that transcends the obligatory reciprocity of typical gift-giving. But object of the WEGE is exactly the opposite of all of that.

Actually, the name WEGE can vary depending on the type of gifts. The specific version of the game typically goes after a particular brand of holiday subversion: shrewd trading and parsimony (e.g., Yankee Swap, Scotch Auction), undercutting holiday beneficence (e.g., Dirty Santa, Evil Santa), turning Christmas on its head by those that are considered inscrutable and untrustworthy (e.g., Chinese Christmas, Chinese Gift Exchange), pointing to the dubious value of the gift or that it might be pre-owned (e.g., WEGE), and/or telegraphing personal gain at the expense of others (e.g., Stealing Santa, Rob Your Neighbor, Cut Throat Christmas).

Basically, the rules are these:

  1. Participants bring an anonymous wrapped gift that fits within prespecified guidelines (price, regifting, etc.) that they slip into the gift pile. 
  2. Everyone picks a number that is used to determine the gift-choosing order of the participants. 
  3. First Turn: The first person called chooses a gift from the pile, opens it, and then displays it to the other participants. 
  4. Second Turn: The next person has three choices. They can either a) steal the gift from the first person, sending them back to the gift pile for another, b) select, unwrap and keep a gift from the pile, or c) select and unwrap a gift from the pile and swap the unwanted gift with the first person. 
  5. All Subsequent Turns: Each new person can steal any unwrapped gift or choose a wrapped gift from the pile. However, a gift can’t be stolen more than once during a turn, and a particular gift can’t be immediately stolen back from the participant who just stole it.

WEGE it isn’t about the personalization, it’s about the stealing. The Machiavellian nature of the game is spelled out in its stealing, its taking, its greed. Rather than the generosity of the personalized, perfect gift, the emphasis is placed on personal gain, creating a series of winners and losers, and getting something for nothing with impunity at the expense of another. I think we can all agree that that is what makes it fun.

You want to make sure that you bring a gift that will engender group favor and can trigger a chain reaction of stealing and hilarity. For example, one of the most popular gifts I’ve seen at one of these events was a big battle axe. Yeah, a real one. How many times it was stolen = funny; who actually wanted a battle axe for their very own = hilarious. In other years, the same group went crazy over gifts like a big stuffed moose or a case of craft beer (I ended up with that one!). So is there a key to picking out the perfect gift for one of these events?

First is to consider your group. Do they appreciate the tacky, silly, and weird or are they more the classy, mainstream crowd? However, slipping a bizarre gift into the latter crowd’s pile will likely cause unexpected amusement. Second is to keep to those prespecified rules. Don’t spend a lot of money trying to impress people; keeping to the anonymity means they won’t know it was you anyway. Next is to not forget the creative wrapping and use it to satirize as well – although you might have to be equally creative to keep it anonymous as you walk into the party.

Herrmann explores the transient nature of both the receiving of the gift and your attachment to it. In the game, the gift itself can be arbitrary and that participants are forced to focus on the transience of possession instead. She cites behavioral economists who describe the “endowment effect,” wherein the brief possession of an item makes it worth more to the owner than other identical items. This extra value makes the stealing of this item even that much more poignant. However, she also points out what we’ve all heard during particularly rousing games: “Give me that! I want it!” so there is at least some value of the item too.

Herrmann breaks down the gifts into three categories:

Fetishized Commodities: Those items that are disproportionately coveted and stolen. My battle axe example is a good one. These gifts take on a life of their own as they gain more value every time they are stolen. A hierarchy of items can emerge as the game goes on. Within this hierarchy are also a series of substrategies like pointing out other gifts to take attention away from yours, loudly hawking lousy gifts in the hopes of trading up, sitting low and hopping no one will see and remember what you have, or even making after-game deals.

Booby Prizes: Of course, no one wants to end up with the “booby prize” or gifts at the undesirable end of the hierarchy. So much so that often the rules will stipulate that the final recipient must take it home with them. It can sometimes be difficult to predict whether a gift will be seen as a booby prize. Perhaps the battle axe was originally meant as a booby prize, a way offload an old D&D costume. But bad became good.

Lazarus Gifts: These are the items that make reappearances in coming years. They are the ones that are most commented on, laughed about, or pawned off. These resurrected gifts actually add to the layers of complexity and amusement of the WEGE.

Ultimately, the WEGE is about group bonding through entertainment. Perhaps that’s why it is so often played at workplace parties. There’s a ritualistic swapping of gifts, but you don’t need to go through the stress of finding the perfect gift. So this year, think of a creative, subversive, fun WEGE gift. Oh yeah, and don’t forget to steal all those good ones away too!


ResearchBlogging.orgM. Herrmann, G. (2013). Machiavelli Meets Christmas: The White Elephant Gift Exchange and the Holiday Spirit The Journal of Popular Culture, 46 (6), 1310-1329 DOI: 10.1111/jpcu.12090



(image via The Lovely Journeys)

Tuesday, December 9, 2014

How to Read a Professor's Door

This comic is so true that I'm considering taping it to my P.I.'s door.



(via PhD Comics)

Friday, December 5, 2014

Adopt-a-Graduate

The semester is coming to an end. This seems appropriate...


Friday, November 28, 2014

Packing on the Pounds: Let the Holiday Eating Season Begin


Here in the U.S., yesterday was Thanksgiving. A time of family, thanks, and lots and lots of food. Be honest, how much did you eat yesterday? Me, I watched a lot of football while I ate appetizers followed by turkey with gravy, mashed potatoes, green bean casserole, cranberry sauce, and cake. Then I entered a food coma for a few hours. It was glorious.

I typically approach a holiday with a journal article, but this time I am going to use the holiday as a jumping off point: Thanksgiving as the start of the holiday eating season. Work parties, family parties, gifts, shopping, etc. All we do for 6 weeks is eat eat eat. And we aren’t eating vegetables, people. A slightly older study from 2006 in Nutrition Journal takes a look at the effect that Thanksgiving has on holiday weight gain.

As with many university studies, this one utilizes their pool of willing college students for their evaluation. However, this isn’t just a story of easy subject access; college students have alarmingly high obesity rates. This demographic gains approximately 0.4-1.8 pounds (0.2-0.8 kg) per year. But is this a result of continual daily increases or more discrete periods of weight gain? That is what this paper aims to answer with this relatively straight-forward study.

The researchers evaluated 94 participants from the undergraduate and graduate programs at their university. These participants visited the human body composition laboratory one week prior to the Thanksgiving holiday break and then revisited again 5-7 days after the break. During these visits, the students were measured for body weight, height, and waist and hip circumferences. From these data, the participants’ body mass index (BMI) was also calculated and categorized as normal (less than 25kg) or overweight/obese (greater than or equal to 25 kg/m2).

They found a significant increase in body weight for the entire group, about 1 pound (0.5 kg). When they broke the group down by characteristics, they found that both males and females gained, and graduate students gained while undergrads did not. When they looked at “fat patterning” (such a lovely, descriptive term), they found a significant decline in waist circumference and waist/hip ratio for the group, males, females, and undergrads. No significant increase in BMI was found in those classified as normal, but those students classified as overweight/obese increased. After calculating correlations, they found the only significant correlation to be in a change in baseline BMI in females. So in general, everyone gains a little weight, but grad students and those already overweight are the most likely groups to pack on the pounds.

The authors discuss a few holiday eating pitfalls: longer eating durations, easy access to food, eating in the presence of others and increased portion sizes. All true. But what they spend zero time discussing is the differences they found between groups, simply stating that the Thanksgiving holiday is “a critical period for weight gain and obesity development.” Um, duh? I would posit that grad students use the holidays as a time to see friends and family and to relax and let loose. That, perhaps, they abandon their normal eat-at-my-desk strategy in favor of home cooked food and lots of wine (and/or beer). For those already classified as overweight, I would say that this demographic already has a problem with food, one that is only exacerbated during this time. For this group, the food challenges are that much harder to resist and all of those pitfalls are magnified.

What are your thoughts? And how do you cope with holiday eating?


ResearchBlogging.orgHull HR, Hester CN, & Fields DA (2006). The effect of the holiday season on body weight and composition in college students. Nutrition & metabolism, 3 PMID: 17192197



(image via The Bella Vita)
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