A Tricky Treat

Seen in its natural form, many may swear they’ve never tried the fruit pictured below. However the foreign looking pods are actually the fruit of the Theobroma cacao, the tree that grows the main ingredient in chocolate, cacao. Below you’ll find a quick Q and A to test your knowledge of the science behind chocolate.

Figure 1. Inside view of the cacao pod. A white pulp surrounds the cacao beans—the main ingredient in chocolate. The pulp can be used to make a juice in some areas, while the seeds contain a large quantity of fat (cacao butter) that allows them to be ground into a fine paste and refined into the treat we know as chocolate!

Who were the first chocolatiers?

The first historical evidence of chocolate reaches as far back as 650BC in the Mayan culture. Archaeologists recently used a combination of high performance liquid chromatography and atmospheric pressure chemical-ionization mass spectroscopy to prove that residue of cacao existed in 14 jars found in Mayan burial sites. The found evidence of cacao in the form of theobromine, a molecule found only in cacao and a few other plants [3].

Figure 2. A vase tested in a recent study for theobromine, an component of cacao plants. The vase is from previously civilizations living in what is now northern Belize

What makes chocolate smell so good?

Chocolate has 600+ compounds volatile compounds that contribute to its smell. Volatile compounds transform into gasses at room temperature and react with odorant receptors in the upper half of the nostril [1]. Recent research shows that some of the individual aromas found in chocolate are human sweat, raw beef fat, and cooked cabbage. So how does chocolate maintain its sweet aroma despite these foul smelling components? According to Gary Reineccius at the University of Minnesota, when more than four scents are simultaneously present, the brain ceases to be able to differentiate individual smells, giving us a pleasant chocolate scent rather than cabbage and human sweat[1].

Is Chocolate really dangerous for my dog?

Yes! One of the main compounds in chocolate is theobromine, a relative of caffeine. Dog and cats metabolize theobromine much slower than humans do, and small doses can lead to poisoning. Dogs have similar tastes for sweets like humans do, so they are more susceptible to consuming a lethal dose of chocolate than cats, who can not taste sweets [6].

Why did the Hershey’s that melted in my pocket turn white once it hardened?

Triglycerides of cacao butter can form six different crystal structures named ß(I) through ß(VI). Each crystal structure is characterized by a distinct melting point, increasing from the lowest melting point, ß(I), to the highest, ß(VI). Most commercial chocolates available contain ß(V) crystal structures, which have a melting point of about 88°F. At temperatures higher than this, chocolate will melt (like the one you left in your pocket), and if not cooled at a slow enough rate, ß(V) crystals will not be able to form properly. The result is a “fat bloom” or a “sugar bloom” which is recognizable in the form of a light colored coating on the chocolate’s surface. In the case of a “fat bloom” cacao butter is separating near the surface, while a “sugar bloom” contains microscopic sugar crystals on the chocolate’s surface. Both blooms result from poor tempering, the process used to make sure chocolate’s temperature throughout its solidification to allow ß(V) crystals to form.

Figure 3. Chocolate that has developed a “fat bloom” due to melting and recrystalizing improperly or an extended shelf life.

Could climate change affect chocolate?

As if the predications of global warming aren’t scare enough, a study published this past September found that climate change in West Africa could actually reduce the suitability of cacao cultivation there [4]. Figure 4 shows all of the locations globally where chocolate is grown, but over half of the world’s chocolate supply is cultivated in Ghana and Ivory Coast. The study looks at climate conditions such as altitude, precipitation and temperature. Ideal cacao-growing temperatures are between 22-25°C globally. At this temperature most cacao can currently be grown between 100-250 meters above sea lever, but increasing temperatures will change the appropriate altitude to 450-500 meters above seal level by 2050. Some environmentalists worry that this shift will increase pressure on endangered forests.

Figure 4: Countries where Chocolate is Grown. Many countries with tropical climates are suitable for growing chocolate.

Figure 5. Change in Land Suitability for Cacao Cultivation Due To Climate Change. A few green regions show prospect for improved suitably as the appropriate growing altitude increases with temperature hikes. However, the overall trend for nearly all of the current growing area is a decrease in suitability.

Works Cited

  1. Arnold, Carrie. “The Sweet Smell of Chocolate: Sweat, Cabbage and Beef: Scientific American.” Science News, Articles and Information | Scientific American. 31 Oct. 2011.
  2. Grassi, Davide, Christina Lippi, Stefano Necozione, and Claudia Ferri. “Short-term Administration of Dark Chocolate Is Followed by a Significant Increase in Insulin Sensitivity and a Decrease in Blood Pressure in Healthy Persons.” American Journal of Clinical Nutrition 81.3 (2005): 611-14.
  3. Hurst, W. Jeffrey, Stanley M. Tarka, Terry G. Powis, Fred Valdez, and Thomas R. Hester. “Archaeology: Cacao Usage by the Earliest Maya Civilization.” Nature. 418.6895 (2002): 289-90.
  4. Läderach, Peter, ed. Predicting the Impact of Climate Change on the CocoaGrowing Regions in Ghana and Cote D’Ivoire. Rep. Managua: International Center for Tropical Agriculture, 2011.
  5. Schenk, H. “Understanding the Structure of Chocolate.” Radiation Physics and Chemistry 71.3-4 (2004): 829-35. Print.
  6. Snyder, Alison. “Fact or Fiction: Chocolate Is Poisonous to Dogs: Scientific American.”Scientific American. 2 Feb. 2007.
  7. Stecker, Tiffany. “Climate Change Could Melt Chocolate Production: Scientific American.” Scientific American. 3 Oct. 2011.

SPOTSHOT & Carpet Removers: How do they work?!

                             

Have you ever been in a situation in your house, bedroom,…perhaps , dorm room…and someone accidentally spills something on the carpet?  I mean how many countless times does your “responsible” mother spill her red wine everywhere during one of her shows (Dancing with the Stars, Desperate Housewives, The Bachelor, etc.)?  Or how about the number of times you return home and see that your loveable golden retriever puppy left you a “treat” on your new Kerastan carpet?  Or even more likely (and surely more applicable to you fratstar college kids)—the number of occasions your college roommate had a bit too much to drink and, well, couldn’t find the trash can quick enough?  Lucky you, there is a quick remedy to save your carpet: SpotShot Carpet Stain Remover.

But seriously, have you ever thought how this magic potion remover actually works?!  Yeah, me neither….until now.  Here’s how:

Most cleaning agents work according to one of four mechanisms.  These mechanisms employ either “like” solvents, surfactants, oxidizing agents, or “whiteners.”  First, the stain remover may contain a certain solvent capable of dissolving the stain, which is based on the popular solubility aphorism “like dissolves like.”  For instance, if your child accidentally wipes his greasy hands all over your carpet, the resulting grease stain will contain a bunch of hydrocarbons.  In order to dissolve this grease stain, you would remove it by using an inorganic solvent containing hydrocarbons, since like dissolves like.  On the other hand, you might have a stain as a result of, say, butter, which is an organic substance.  As a result, you would want to remove the stain using an organic solvent, such as tetrachloroethylene.  This technique, based on picking a solvent similar to your stain, is the same technique implored in dry cleaning.

Sulfunate ion

A second approach—and the most frequently used in stain removers—employs surfactants, such as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.  Soap is a common surfactant, but stain removers often use sulfonates (pictured left), which are salts of sulfonic acid.  Surfactants are usually organic, amphiphilic compounds.  Amphiphilic molecules contain both hydrophobic groups and hydrophilic tails, so that they contain both a water-insoluble and a water-soluble component.  Thus, a surfactant molecule contains a long, hydrophobic tail with a small, polar head.  The hydrocarbon tail can surround (i.e. dissolve) the grease stain, and the polar ends dissolve in water.  As a result, these surfactant molecules can interact with each other, forming a micelle around a “stain” molecule (pictured below).  This micelle is water-soluble and gets washed away.  In this process, which is called emulsification, stains are thus removed via the formation of micelles by surfactant molecules around inorganic (or organic) stain molecules.

Micelle

A third mechanism stain removers might use involves “eating the stain.”  By using oxidizing agents, such as chlorine bleach or peroxides, stain removers can break the bonds holding the long-chain stain molecules together.  The products of this oxidation reaction are water-soluble and can be washed away more easily by the solvent.  In food-related stains, biological and enzyme detergents work well since they release enzymes that act as catalysts to speed up the chemical digestion of the proteins and fats in these stains.

Lastly, the fourth approach (and certainly a “shortcut” or “last resort” for stain removers) essentially hides the stain from eyesight.  They employ detergents like bleach that disrupt the bonds between chromophore molecules, which absorb light at specific wavelengths, re-emitting it as visible light to produce “color.”  In this case, the optical properties of the stain molecule are changed and seem to be “colorless.”  So with this technique, although we may say that the stain left from dog doo on your living room carpet has been “removed,” the dog doo is actually still there: it just is no longer visible.  Comforting…it makes you think twice about lying down on that carpet of yours, huh?

In sharing these stain-removing properties with you, I hope you have had some sort of “common sense science” revelation.  We often overlook simple everyday items and how they might function.  However, it is important to realize that these seemingly simple items function scientifically—whether chemically, biologically, physiologically, or physically—and that we can benefit from understanding the scientific principles that they employ, no matter how basic or how intricate they may seem.

http://antoine.frostburg.edu/chem/senese/101/consumer/faq/stain-removers.shtml

http://www.cip.ukcentre.com/soap1.htm

http://en.wikipedia.org/wiki/Sulfonate

http://www.youtube.com/watch?v=y3AdOsRAipU&feature=related

Music to My Ears

Walking around Julian, Roy O. West Library, or any other study space on campus, you are sure to see students working hard on their assignments while listening to music on their ipods or computers. Many students claim that the music helps them block out the surrounding distractions and concentrate on their work. Although students have a variety of musical interests, the common thought is that listening to classical music, such as Wolfgang Amadeus Mozart, is the best choice for studying. Research on the effect of listening to music, however, is not so clean cut.

On one hand, it would seem contradictory that dividing the brain’s function between two tasks, studying and listening to music, would provide an improvement to having the brain focus solely on studying. On the other hand, listening to music may stimulate the brain and enhance the student’s ability to study.

As it turns out, it may depend on how often you listen to music when you study. A study done at Bradley University gave reading comprehension tests to 16 male and 16 female college students. Half of each gender were given the test in a quiet setting, while the other half took the test with music of their choosing (many previous tests did not allow subjects to choose their music). The subjects read the passage for 10 minutes and then answered  5 questions without looking back at the reading. The mean reading comprehension score in the music condition for maIes was 6.9 and for females, 6.6. In the no-music condition, mean scores for males and females were 6.6 and 8.6, respectively. While it appears that the music had no major effect on the males and a large effect on the females, the results also showed that the frequency that the students study with music was also significant. Among females, two reported that they frequently studied to music, 4 said occasionally, and 10 reported never. Of the male subjects, 5 reported frequently studying to music, 6 said occasionally, and 5 reported never. Thus, females studied to music less often than did males. The distracting effect that the music had on the females studied can be explained by the fact that they were not used to studying with music.

A more recent study at the University of Wales Institute in Cardiff, United Kingdom, suggests that music may actually hurt your studying if you are trying to memorize and ordered list, such as numbers, facts, or dates. Participants were tested under various listening conditions: quiet, music that they’d said they liked, music that they’d said they didn’t like, a voice repeating the number three, and a voice reciting random single-digit numbers. They then instructed 25 participants between ages 18 and 30 try to memorize, and later recall, a list of letters in order. The study found that participants performed worst while listening to music, regardless of whether they liked that music, and to the speech of random numbers. They did the best in the quiet and while listening to the repeated “three.” The researchers hypothesized that your brain might get thrown off it’s attempt to memorize a sequence by the changing words and notes in a song. This study, however, does not completely contradict previous studies that show music’s benefit. It simply points out that there may be limitations on the types of studying that are enhanced by listening to music.

But what is actually happening in the brain that would cause the positive or negative effect of listening to music while studying. Recent research using functional magnetic resonance imaging, or fMRI, allows scientists to see what the brain is doing and take pictures and videos of its activity. Using this technology, a research team from the Stanford University School of Medicine research team showed that music engages the areas of the brain involved with paying attention, making predictions and updating the event in memory. A link to the video is here: http://med.stanford.edu/news_releases/2007/july/music.htmlSubjects listened to short symphonies by 18th century composers while undergoing the fMRI to image their brain. What surprised them was that the peak brain activity came during the short time period in between musical movements.

So what does all this research mean, and how does it apply to you?

First, if you currently listen to music while you study, you can continue. If, however, you are thinking starting to listen to music for the first time, you may want to stop and rethink. Starting this new activity during your studying may distract you until you become used to it.

Second, it depends on the type of studying you are doing. If you are trying to memorize a list, ordered process, or the digits of pi, listening to music will hinder your studying.

Third, to increase your brain activity, only listen to the transitions in between songs on your ipod. This suggestion may not be particle, but you can try it if you want.

References:

Baker, M. “Music moves brain to pay attention, Stanford study finds.” Web. 30 Nov. 2011. http://med.stanford.edu/news_releases/2007/july/music.html

Landau, E. “Music may harm your studying, study says.” web. 30 Nov. 2011. http://thechart.blogs.cnn.com/2010/07/27/music-may-harm-your-studying-study-says/

Etaugh, C. and Michals, D. “Effects on Reading Comprehension of Preferred Music and Frequency of Studying to Music.” Perceptual and  Motor Skills,  1975, 41 , 553-554.

Trash Talk

With all the recent talk of being “green”, many people have begun to make small changes to do their part. Living on my own I have vowed the same. Since I live in a duplex, without a yard, I am unable to compost so I have begun using my garbage disposal religiously.

Have you ever thought about how your garbage disposal works? Well, neither had I. Most people view their garbage disposals as being mysterious, you flip a switch and it works. That’s all most people care to know, though how a garbage disposals works is actually quite simple.

It is commonly thought that a garbage disposal works like a blender, with spinning blades chopping and breaking down the food. In reality disposals work in a different way and there are NO blades involved. Instead, impellers (or lugs) mounted on a spinning plate use centrifugal force, at a speed of almost 2,000 RPM, to continuously force food waste particles against a sharp-toothed inner wall. The wall breaks down the food waste into very fine particles, practically liquefying them. This process is most commonly interrupted, causing a jam, when the food placed in the disposal is either too large or too firm for the machine to handle. In these instances, the food will usually fall beneath the plate where it cannot be broken down properly. Keeping this in mind, large or firm pieces of food should not be placed directly into the disposal, but should first be broken down by hand into a workable size. Once pulverized, the running water flushes the particles through the inner wall, out of the disposer, and into your wastewater pipe. From there it flows into your septic system or to the wastewater treatment plant.

There are two common types of garbage disposals available that differ slightly from one another; continuous feed and batch feed. A continuous feed disposal operates, once switched on, by feeding food and water from the spinning plate to the inner wall and then finally to the drainage pipe. Batch feed disposals work in a similar way, except for the fact that a stopper is placed in the disposal. After loading a batch feed disposal, the stopper activates a switch which turns it on. Continuous feed disposals are considered to be more user-friendly, and are therefore more common, than batch feed disposals.

I hope you enjoyed learning about a little bit about your garbage disposal, but if you’re craving a bit more, here are some fun facts…
• John W. Hammes invented the garbage disposal in 1927 for his wife (apparently she didn’t want a vacuum cleaner). He spent eleven years refining his invention before starting his own garbage disposal business. The name of his company? The In-Sink-Erator Manufacturing Company.
• In nations with ready access to water and an industrial base, such as the United States, garbage disposals are common fixtures.
• In the US approximately 50% of homes had garbage disposal units in2009, compared with only 6% in the UK.
• Garbage Disposal Energy usage is not high; typically 500 to 1500 watts of power are used. This is comparable to an electric iron, but only for a very short time. Per year, this totals to approximately 3-4 kilowatt hours of electricity per household. Daily water usage varies, but is typically one gallon of water per person per day, comparable to an additional toilet flush.
• Food scraps range from 10 – 20% of household waste, and can be a problematic component of municipal waste. Burned in waste-to-energy facilities, the high water-content of food scraps does not generate energy; buried in landfills, food scraps decompose and generate methane gas, which is considered to be a potent greenhouse gas.
• The premise behind the proper use of a disposal is to effectively regard food scraps as liquid (averaging 70% water, like human waste), and utilize existing infrastructure (underground sewers and wastewater treatment plants) for its management. Modern wastewater plants are effective at processing organic solids into fertilizer products (known as biosolids), with advanced facilities also capturing methane for energy production.

References
Formisano, Bob. “Anatomy of a Garbage Disposal.” Home Repair. About.com. Web. 26 Nov. 2011. .
“Garbage Disposal: Facts, Discussion Forum, and Encyclopedia Article.” AbsoluteAstronomy.com. Web. 27 Nov. 2011. .
In-Sink-Erator Staff. “How Garbage Disposals Work.” InSinkErator. Web. 26 Nov. 2011. .
Larsen, Kurt. “How A Garbage Disposal Works.” Home & Garden Ideas. The Writers Network, 24 Feb. 2011. Web. 26 Nov. 2011. .
Vandervort, Don. “Home Tips : How a Garbage Disposal Works.” Home Tips. Web. 26 Nov. 2011. .

Food Cravings and what those foods do to your brain!

Ever find yourself staring at that delicious chocolate cake or pumpkin pie on the shelf and with your mouth watering just at the sight of it? Then you know how craving food feels like.

Scientists define food craving as the intense desire for a very specific food and your willingness to go out of your way to receive it. A lot of us blame ourselves for giving into those cravings “letting go” by indulging into something either sweet or very fatty, but there are many scientific facts that now allow us to understand why those foods are so tempting.

Many questions may arise when you think about food craving and I will attempt to answer a couple with this post, starting with: What types of foods do we crave and why?

Many of us think of craving as the desire for something sweet, but scientists at Tufts University did a wide study, where they found that even though sugary foods are preferred, fats are not left behind. The craving for a specific type of food differs on a personal basis, but we mainly tend to go for foods that are very calorie dense and tend to go for a combination of carbohydrate and fat rich food. An interesting thing that those researchers also found is that the craving intensity did not depend on body mass index of the people tested. Lean people experienced just as much craving as obese ones, but the obese ones would need bigger amount of food to satiate that craving.

So why do we have those cravings is the next most logical question? The only theory that holds strong logic in this case is derived from our evolutionary history. Any species needs nutrition to survive and through the years nutrition has not been as readily available as it is now. Thus, it would be more beneficial for our predecessors to find food that is highly packed with those vital calories they would need. So in the idea of “survival of the fittest”, the fit specimen would be the ones able to find enough calories to survive, thus the ones that seek them most avidly are the ones that find them. On the other hand, that doesn’t mean that you can blame your ancestors for all your cravings, it’s partly your fault!

Now that we know that we can partly blame evolution this leads us to two more questions: What exactly happens that causes us to crave and why are we in part to blame for cravings?

Researchers at Johns Hopkins Medical School have found that there are specific centers that light up in the brain on a functional MRI (magnetic resonance imaging) when people think about foods they crave. The fact that those sections light up, shows they are activated. The more interesting thing is that those sections don’t activate when we think about low calorie food, but also that those are the same parts of the brain connected to drug addiction.

The amygdale, hypocampus and nucleus accumbens are strongly associated centers of pleasure. Those are the same places that drugs activate and those are the same places activated by the sight or thought of craved foods. Through those images the researchers also found something even more fascinating: when lean people consume craved food those sections light up more strongly than in obese people. Lesson learned – leaner people experience more satisfaction from the food than obese people, who have to consume more to receive the same satisfaction.

So why should we in part blame ourselves for our cravings? The more often you indulge on these “craved” foods you train your brain to get accustomed to them, a process called “sensitization.” The more accustomed your brain is, the less satisfaction you receive from eating that food you craved. The less satisfaction you get the bigger amount you crave. It is a vicious cycle that leads into obesity and depression very fast. Food addiction is real and it is not to be undermined.

To leave you on a positive note all of this is to just remind you that “craving” food is absolutely normal and 96% of people experience it. The difference is that if you indulge on that craving frequently it will become stronger. The good side is that like any addiction it can be overcome. As long as you stick to a good diet, it is estimated that you can go back to the same amount of craving as a “lean” person within 3-6 months. Hope that helps!

Sources:

Beaver, J., et. al. “Individual Differences in Reward Drive Predict Neural Responses to Images of Food.” Journal of Neuroscience. Vol. 26(19) Pg:5160 –5166. May 10, 2006

Pelchat, M. et. al. “Images of desire: food-craving activation during fMRI.” NeuroImage. Vol. 23. Pg 1486-1493. 2004

Bryant, R., Dundes, L. “Fast food perceptions: A pilot study of college students in Spain and the United States.” Apetite. Vol 51. Pg. 327-330. 2008

Gilhooly C., et. al. “Food cravings and energy regulation: the characteristics of craved foods and their relationship with eating behaviors and weight change during 6 months of dietary energy restriction.” International Journal of Obesity. Vol 12. Pg 1849-58. 2007

Tufts University, Health Sciences. “Links Between Food Cravings, Types Of Cravings, And Weight Management.” ScienceDaily, 18 Jul. 2007. Web. 24 Nov. 2011


Dirty Mouth? The Science of Teeth Whitening

It seems that as we move further into the 21st century, Americans are using modern techniques to evade everyday responsibilities. Overweight people get liposuction to avoid exercise, singles use the internet to find their “soulmate,” and parents pick up fast food to avoid cooking and cleaning. Another example of this is teeth whitening. I admit, I have on occasion used teeth bleach, simply to whiten my teeth after years of braces, or to give my smile a like “pick-me-up.” However, there are people out there that depend on this process to replace teeth brushing. Sure, it seems harmless and an easy fix to not brushing your teeth twice per day, but what it really happening in your mouth? How are the chemicals in teeth bleach physically changing the color of your teeth? Is it harmful to whiten too often? Let’s explore the scientific processes behind a few different methods of teeth whitening…

First of all, what are teeth even made of? The somewhat translucent, exterior layer of the tooth is called “enamel,” which is made of a crystalline calcium phosphate (a mineral). Since it’s made of so much mineral, it is very strong yet brittle. The criss-crossing layer of minerals creates rod-shaped holes in the enamel, making is porous. The layer underneath the enamel is called “dentin,” which is made up of the same material as enamel in combination with water. It is yellowish in appearance, which causes some teeth to become yellow when they are not clean.

.

After eating different types of food, another layer called the “pellicle” gradually starts to form on top of the enamel. This layer can be brushed away by a toothbrush or by a dentist who can scrape it off. However, the enamel is porous, so the pellicle (or stain) can get deep into the dentin after years of the pellicle sitting on the tooth. Bleaching agents in whiteners can get down into the dentin to remove these stains. Let’s take a closer look…

“Dentist Supervised” whitening involves the use of a gel that consists of a certain percentage (15-35%) of hydrogen peroxide coupled with the use of a UV light. The hydrogen peroxide, upon entering the tooth, releases “free radicals” to “oxidize” the stain beneath the enamel. Confused yet? It’s really very simple. A free radical is an atom, molecule, or ion with unpaired electrons. When something is oxidized, it loses electrons. Thus we can safely assume that the electrons in the organic compounds in the stain are being donated to those in the free radicals released by the bleach. This causes the degeneration of the stain, and thus the yellow color to disappear. Adding light to the equation accelerates this whitening process.  UV light is known to accelerate many chemical processes, including the oxidation of the stains in your teeth. So while you do have to sit with your mouth open and a light stuck in it for about 30 minutes to 1 hour, you’ll only have to go in once and you won’t have to keep bleach in your mouth for hours at a time.

As you all know, we can obviously also whiten our teeth at home. The difference here is the use of a lower concentrated (10-20%) carbamide peroxide gel (and more time consumption, unfortunately). Carbamide must be broken down into hydrogen peroxide during a separated chemical reaction first during the chemical reaction, which is why it takes longer than if you went to the dentist. Using either custom-made “trays” or over-the-counter “strips.” You can eventually achieve similar results to those from the dentist’s office. You must be careful, however, not to get the gel onto your gums, which are made of soft connective tissue. Leaving hydrogen peroxide on them for too long can causes burns, which will leave your mouth sensitive for a few days.

Hydrogen Peroxide

Carbamide Peroxide

So there you have it, a bleaching gel in combination with UV light causes a simple chemical reaction that removes stain below the enamel layer of teeth. So popular contrary belief, it is science, not magic that changes the color of your teeth. And even though you may be removing the stain, you are not removing permanent damage done to enamel by not brushing your teeth (I’m talking cavities, my friends).

References:

1. “The Chemistry Associated with Peroxide-Based Teeth Whiteners” http://www.dental-picture-show.com/teeth_bleaching/a3_teeth_whitening_science.html

2. “Teeth Whitening – How it Works and What it Costs” http://www.yourdentistryguide.com/teeth-whitening/

3. “Antioxidants and Free Radicals” http://www.rice.edu/~jenky/sports/antiox.html

4. “The Art and Science of Tooth Whitening” http://www.ncbi.nlm.nih.gov/pubmed/15828604

Easy Mac, Spaghettios, and left overs…What would we do without microwave ovens?

First off, who am I and why should you trust me?…

I am a senior biochemistry student at DePauw University in beautiful, small, middle of no-where Greencastle, IN. I am originally from Knoxville, Tennessee, so if you’d like you can imagine this post was written in a Southurn accint. My background is mostly in biochemistry, but as an aspiring med student I’ve also taken two semesters of physics. I did pretty well in those two semesters, and I’m confident I learned enough to research the basics of microwave physics and explain them to you here. I have also have an extensive history with microwavable food…I currently eat Lean Cusines and Campbell’s Soup on a regular basis while I’m at school…so I’d like to think you can trust me when I say I am a microwave expert of sorts.

Everyday when my brother and I came home from school he would open a can of Spaghettios, pop them in the microwave, and wait the 2 or 3 minutes until they were warm and ready to eat. When I was younger I just inherently knew that if you put something in the microwave and turned it on for long enough the food would get warm, but how does a microwave oven actually heat up your food?

Microwave ovens actually use microwaves- a form of electromagnetic radio wave to heat food. Electromagnetic radiation is a form of energy that has both electric and magnetic field components and exhibits wave-like behavior as it travels through space (4). Radio waves have the longest wavelength and the lowest frequency in the electromagnetic spectrum (seen below), making them the lowest energy EM wave based on the Plank-Einstein relationship (E = hc/λ) which says the energy of an electromagnetic wave is directly proportional to the Planck Constant (h) and the speed of light (c) but indirectly proportional to wavelength (4).

In the case of microwave ovens, the frequency of radio wave usually used is about 2,500 megahertz (4). Interestingly, microwaves at this frequency are absorbed by water, fats and sugars and are not absorbed by most plastics, glass or ceramics. As the water, fats, and sugars in your Spaghetios or Pop-Tart absorb the microwaves they heat up by a process called “dielectric heating.” The molecules are dipoles, meaning they have a positive and negative charge on opposite ends. The dipoles begin to spin as they try to align themselves with the alternating electric field of the microwaves, causing them to rub together and create heat (3). The heat produced by the the water, fat, and sugar molecules in your food rubbing together begins to heat the molecules around them and, essentially, to cook your food! The length of time required to cook your food, therefore, depends on its water, fat, and sugar content in relation to its size.

…So, where do the microwaves come from? The microwaves are generated by a magnetron within the oven. Magnetrons were invented in 1921 and then vastly improved in the 1940s (2). The physics of a magnetron is a little beyond the grasp of this blog, but in layman’s terms it is essentially a tube that moves electrons through a magnetic field which causes the electron path to curve and create oscillating microwaves (2).

The microwaves are then corralled into the cooking box by the waveguide where they bounce around, reflected by the metal of the box, until they are absorbed by your food. Microwaves are a common household object around the world. We use them to heat up left-overs, cook microwave dinners, and to pop popcorn before we sit down to watch a movie. I hope you enjoyed learning about a little bit about the science behind these household marvels, but in case you’re craving a little bit more knowledge, here are some fun facts…

  • Microwaves cook your food from the inside out, as opposed to a conventional oven which cooks food from the outside in by the process of convection. This is why Hot Pockets have a little metal casing around them which allows heat to be reflected back at its surface creating a crust! (1)
  • Microwaves aren’t nearly as efficient at cooking frozen foods because the molecules are not free to rotate. (3)
  • As of 1971 only about 1% of American homes had a microwave. That number rose to 25% by 1986, and as of 2009 90% of American households had a microwave.
  • Microwaves convert Vitamin B12, an essential vitamin predominantly found in meat, to an inactive form. (3)
  • However, spinach retains almost all of its folate when cooked in a microwave, but loses approximately 80% when it is cooked on a normal stove. (3)
  • The first documented use of the term “microwave” was in 1931. It was used in a Telegraph and Telephone Journal, which said “When trials with wavelengths as low as 18 cm were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon.” (3)

References:

1. Brain, Marshall. “HowStuffWorks “Microwave Cooking”” HowStuffWorks “Home and Garden”2011. Web. 16 Nov. 2011. <http://home.howstuffworks.com/microwave2.htm&gt;

2. Gallawa, Carlton. “The Magnetron Used in Microwave Ovens: Structure and Operation.” Gallawa Family Web Site. 2008. Web. 16 Nov. 2011. <http://www.gallawa.com/microtech/magnetron.html&gt;.

3. “Why You Generally Shouldn’t Put Metals in the Microwave.” Today I Found Out: Why You Generally Shouldn’t Put Metals in the Microwave. Vacca Foeda, 2010. Web. 16 Nov. 2011. <http://www.todayifoundout.com/index.php/2010/08/why-you-generally-shouldnt-put-metals-in-the-microwave/&gt;.

4. Vollmer, Michael. “Physics of the Microwave Oven.” Physics Education 39.1 (2004): 74-81. Print.