Could Making Beer From Sewage Save Us From The Drought?

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[Photo Credit: Vince C Reyes]

[Photo Credit: Vince C Reyes]

The historic drought in California and other U.S. states challenges us to rethink the way food production and consumption shapes our available water supply. To that end, one adventurous brewing club, The Oregon Brew Crew, collaborated with Oregon’s water utility, Clean Water Services, to brew beer from waste water. This comes as part of the water utility’s initiative to make better use of recycled water. As beer is 95% water, we could potentially save significant volumes of water through this less glamorous route.1

To be clear, the brewers did not make beer straight from water entering out of the toilets and sewers of Oregon. Clean Water Services provided the brewers with “ultrapure water” for making their beer. Ultrapure water is made from water that is purified using the most advanced water treatment methods available. Ultrapure water is not new, but is normally not used for brewing. It is traditionally used for generating water for electronics and pharmaceuticals production, scientific research, or any other application where water must be free from as many contaminants as possible.

To generate ultrapure water, Clean Water Services combines traditional wastewater treatment with more advanced methods. For this process, sewage is first cleaned using traditional wastewater treatment, which includes screening, sedimentation, biological treatment, and disinfection. After this step, the sewage is fit to be released to lakes and rivers, but gets a deeper cleaning through more advanced methods. In the case of the water used by the brewers, Clean Water Services uses a three-step process of Ultrafiltration, Reverse Osmosis, and Enhanced Oxidation to produce their ultrapure water.

The water is first subject to Ultrafiltration and Reverse Osmosis. These processes work like a kitchen sieve as they push water through small pores in a barrier to separate water from different molecules. While both Ultrafiltration and Reverse Osmosis use similar physical separation mechanisms, they vary in the products they can remove from water because of their differing pore sizes. Ultra-filtration can be used to remove particles as small as viruses and bacteria (0.005 – 0.5 μm), while Reverse Osmosis uses finer pores, which can remove even smaller molecules like herbicides, pesticides, salts, and metal ions (0.0001 – 0.001 μm) (Figure 1).

Figure 1: The size of materials that can be removed by Ultrafiltration and Reverse osmosis. Figure Credit: Designerwater.co

Figure 1: The size of materials that can be removed by Ultrafiltration and Reverse osmosis. [Figure Credit: Designerwater.co]

In contrast to Ultrafiltration and Reverse Osmosis, the final step, Enhanced Oxidation, uses chemical methods to eliminate any remaining unwanted products in water. Specifically, Enhanced Oxidation uses ultraviolet (UV) light in combination with chemicals like hydrogen peroxide (H2O2) and ozone (O3) to generate hydroxyl radicals. The high energy from the UV light breaks down chemical bonds to form hydroxyl radicals (·OH). For example, here is the break down of hydrogen peroxide by UV light:

H2O2  + UV -> 2·OH

A hydroxyl radical is just a hydrogen atom bonded to an oxygen atom with an extra electron. Having an extra electron makes hydroxyl radicals very reactive and can break down undesirable molecules in water. This final step removes any remaining contaminants that were not eliminated by Ultrafiltration and Reverse Osmosis.

Figure 2: Ultrapure water (high purity water) compared to river water, cleaned sewage water, and tap water. [Image Credit: huffingtonpost.com]

Figure 2: Ultrapure water (high purity water) compared to river water, cleaned sewage water, and tap water. [Image Credit: huffingtonpost.com]

After these three treatments, the ultrapure water was ready to be used for brewing. In regards to taste, this process produced bland tasting water that results from the absence of minerals and salts that are normally found in water from groundwater, reservoirs, lakes, rivers, and the tap2. These atoms and molecules can be challenging for brewers, as they impart a natural flavor to waters that may not be congruent with the desired beer’s flavor profile3. Instead, when using ultrapure water, the brewers had the freedom to build in whichever flavors they desired. The hops, grains, yeast, and additional spices controlled the beer’s flavor profile rather than the water.

Currently in the U.S., recycled water typically cannot be used directly as drinking water, regardless of how much it is cleaned. Generally, recycled water is only used to water landscape, cool power plants, or flush the toilet. But with growing concerns over shrinking water sources, these views are changing. In 2010, a study by the California State Water Board examined the potential contaminants in recycled water, current water treatment technology, and human health studies of exposure to these contaminants. The conclusion was that recycled water could be safe for human consumption4. These results have been confirmed by other research as well5.

Projects like this may cause you to re-evaluate your bias about the source of your water (and beer). Regardless of the origin of your water, advances in water treatment technologies may enable us to produce safe drinking water from wastewater. But the question still remains: would you feel comfortable raising a glass of beer made from recycled waste water to your lips or would you pour it down the drain?

Learn More

  1. “Water and Wasterwaster: Treatment/Volume Reduction Manual” Brewers Association.
  2. “Is Sewage Beer The Next Big Thing?” Huffington Post.
  3. “To Grow A Craft Beer Business, The Secret’s In The Water” NPR: The Salt.
  4. “Final Report: Monitoring Strategies for Chemicals of Emerging Concern (CECs) in Recycled Water” State Water Resources Control Board.
  5. Rodriguez, C., Buynder, P.V., Lugg, R., Blair, P., Devine, B., Cook, A., Weinstein, P. Indirect Potable Reuse: A Sustainable Water Supply Alternative. International Journal of Environmental Research and Public Health. March 2009; 6(3): 1174-1209.

Vince ReyesAbout the author: Vince C Reyes earned his Ph.D. in Civil Engineering at UCLA. Vince loves to explore the deliciousness of all things edible.

Read more by Vince Reyes

Alton Brown’s Jet Cream Ice Cream

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Because you are currently reading a blog about science and food, there is a high probability that you have seen or at least heard of Alton Brown: host of Good Eats and about five other Food Network television shows. There is also a significant probability that you’re a mega-fan of Alton Brown, and if so, that’s something you and I have in common. I have been watching the bespectacled nerd-chef (I say that admiringly) since I was thirteen, and he has largely inspired my food science endeavors. On March 19th I had the absolute pleasure of attending Alton Brown Live! The Incredible Inevitable Tour in Napa, California.

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Alton describes the show content as all the things he can’t do on TV, including stand-up comedy, live music, and most excitingly, showing off his insane kitchen inventions. Because even the thought of burning myself on MegaBake terrifies me, we’re going to work through the science behind his colder contraption: Jet Cream.

Making ice cream is usually a simple process. Once you have your cream mixture, it simply needs to be repeatedly cooled and agitated. If we simply froze ice cream base, we’d get huge ice crystals, which aren’t necessarily bad. Dessert shops like Blockheads and Chilly Ribbons sell “Snow Cream,” that results from shaving fine sheets from a block of frozen milk or cream. But if we want ice cream, as Alton clearly does, we must continually add air to the cream and disrupt the crystallization process to make tiny crystals that are barely perceivable on the tongue. That’s why ice cream is smooth and unctuous, while frozen milk is crisp and icy. Whether you’re shaking a container of cream surrounded by ice by hand or using an industrial ice cream machine, the goal is to keep ice crystals small.

Alton’s goal is no different. To make ice cream, all he needs to do is simultaneously freeze and agitate his chocolate cream. His Jet Cream machine is an extravagant way to do a huge batch all at once, and in less than ten seconds. Rather than use ice and salt in a bason like pioneers did, or use liquid nitrogen like the modern gastronome, he uses compressed carbon dioxide via fire extinguisher.

When the fast-flying molecules of carbon dioxide gas are compressed into the extinguisher, they are stored at a very high pressure, typically 825 pounds per square inch. [1] A fire erupts on the stove, or you have a sudden urge for ice cream, so you pull the lever. The pressure is released; the gas flies out, and the nozzle and surrounding air become extremely cold, as tends to happen when a  gas suddenly expands from a high pressure to a low pressure. The change in temperature divided by the change in pressure makes a ratio (∆T/∆P) known as the Joule-Thomson coefficient.[2] The nozzle and surrounding air are chilled because the gas’ pressure change occurs too quickly for significant heat transfer to occur. For many gases at room temperature, as the CO2 in the extinguisher is, the ∆T/∆P ratio is positive, so a pressure drop is accompanied by a temperature drop. The molecules that were once speeding around inside the canister are now so low-energy that they form solid CO2, or dry ice. Dry ice is much, much colder than regular H2O ice because carbon dioxide freezes at -109 degrees Fahrenheit, while water freezes at 32 degrees. [3] Colder temperature = faster crystallization = quicker ice cream.

Photo Credit: David Allen, The Eater

Photo Credit: David Allen, The Eater

Now for the agitation: At the other end of Alton’s Jet Cream contraption is a typical water fire-extinguisher filled with chocolate cream. When this lever is pulled, a high-pressure spray of chocolate ensues. Between the two extinguishers are office water cooler jugs that act as the reaction chamber for the CO2 and cream. If the two levers are pulled exactly at the same time (synchronicity is very important in avoiding a catastrophic mess, stresses Alton), the blasts of cold and cream will collide in the coolers, providing the continual disturbance of the freezing process, as well as the incorporation of air, necessary to make tiny tasty ice crystals.

After plunking a scoop into a sugar cone and applying a generous coat of rainbow sprinkles, Alton hands off his creation to his volunteer assistant and asks if it is not the best ice cream he has ever had. Volunteer assistant replies that it is “So good.”

So there you have it. If you want ice cream that is “so good,” and you want a gallon of it fast, Jet Cream is the contraption for you.

 

Photo credits: instagram.com/altonbrown/

Photo credit: instagram.com/altonbrown/

References cited:

  1. “CO2 Fire Extinguishers.” Fire Extinguisher Guide. N.p., n.d. Web. 06 Apr. 2015.
  2. “Joule Thomson Effect.” Wright State University – Department of Chemistry.  N.p., n.d. Web. 06 Apr. 2015
  3. “UCSB Science Line.” UCSB Science Line. N.p., n.d. Web. 06 Apr. 2015.

Elsbeth SitesAbout the author: Elsbeth Sites is pursuing her B.S. in Biology at UCLA. Her addiction to the Food Network has developed into a love of learning about the science behind food. Read more by Elsbeth Sites

Rose

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Ah, spring. The perfect time of the year to take a stroll, smell the roses, and then stop by the local bakery to taste the roses. Whether in Persian or Middle Eastern desserts such as rose-flavored raahat or baklava, or French-inspired rose scones and marshmallows, roses have an elegant flavor that is a delicate mix of sweet and floral. In celebration of spring, here are 7 things about the flavor of roses to mull over while enjoying a cup of rose hip tea: Read more

The Science of Bacon

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MTN_bacon

Photo Credit: Mai Nguyen

Imagine rolling out of bed on a Saturday morning, shuffling into your kitchen, and tossing a few strips of streaky bacon into a skillet. After a few minutes, you’ll hear a delightful crackling and sizzling, soon followed by a complex and savory aroma that could lure even the most resolute of vegetarians to the kitchen. As time passes, you peek into the skillet and notice the bacon begin to brown and bubble. After an agonizing wait, the bacon has finally reached a desired color and crispness and is ready to be consumed. You eagerly bite into a strip of bacon and are met with a pleasantly smoky taste, crunch, and a melt-in-your-mouth sensation. Bacon is a delight to eat, but it’s even better when you understand the science of why it’s so delicious.

There are two major factors that can explain why bacon has such a devoted fan base, with the first and more obvious factor being its aroma. Scientists have identified over 150 compounds responsible for bacon’s distinctive smell. As bacon cooks, there are a couple of different things going on. The Maillard reaction, the browning that results when amino acids in the bacon react with reducing sugars present in bacon fat, produces several desirable flavor compounds. This same browning reaction is also what forms the darkened and crunchy exterior on a pretzel or provides a stout beer with its characteristic color and taste.

During this process, bacon fat also melts and degrades into flavor compounds of its own. The compounds produced from the Maillard reaction and from the thermal degradation of bacon fat combine to form even more aroma compounds. In one study, scientists used gas chromatography and mass spectroscopy and revealed many of these aroma compounds to be pyridines, pyrazines, and furans, which were also found in the aroma of a fried pork loin that was tested. Pyridines, pyrazines, and furans are known to impart meaty flavors, so what actually sets bacon apart from the fried pork loin is the presence of nitrites. Nitrites are introduced into bacon during the curing process and are believed to react with aroma compounds in such a way that dramatically increases the presence of other nitrogen-forming compounds, including those meaty pyridine and pyrazine molecules. Ultimately, we can thank the high presence of nitrogen compounds as well as the interplay of fat, protein, sugars, and heat for bacon’s savory and unique aroma [1].

Now imagine that you’re eating breakfast. You alternate between bites of fluffy pancake drenched in maple syrup and mouthfuls crispy bacon, and maybe you’ll also have a side of velvety scrambled eggs. Here, you have a variety of textures on your plate –which brings us to our next concept to explain why bacon is so revered—mouthfeel.

Mouthfeel is described as the physical sensations felt in the mouth when eating certain foods. Bacon delivers a crunchy contrast to the softer textures found in scrambled eggs or pancakes in a mouthfeel phenomenon known as dynamic contrast. The brain craves novelty, and sensory contrasts will often increase the amount of pleasure that the brain derives from food, which is why you can find bacon as a textural accompaniment in many classic, creative, or sometimes questionable combinations. In a strip of bacon, you’ll see that it consists of lean meat that is heavily marbled with fat. During the cooking process, fat renders off leaving behind a product that simultaneously crisps and melts in your mouth when consumed, a texture combination that is rivaled by few other foods.

The melt-in-your-mouth phenomenon of bacon illustrates another nuance of mouthfeel, which is vanishing caloric density. Vanishing caloric density can be blamed for why it’s so easy to mindlessly consume massive amounts of popcorn, cotton candy, or other foods that seem to melt in your mouth. Upon ingestion of these foods, it is believed that the brain is tricked into thinking that you’re eating fewer calories than you actually are. Foods with vanishing caloric density have low satiating power but high oral impact, so your brain urges you to consume more, as it finds them more rewarding [2].

Between its tantalizing aroma and its delectable mouthfeel, it’s no surprise why bacon mania has so aggressively swept the nation.

MTN_bacon2

Now you can use science to justify eating an entire package of bacon in one sitting. Photo credit: Mai Nguyen

References cited

  1. Timón, M., Carrapiso, A., Jurado, A., van de Lagemaat, J. A study of the aroma of fried bacon and fried pork loin. Journal of the Science of Food and Agriculture, 2004; 84:825-831.
  2. Witherly S. Why Humans Like Junk Food. iUniverse, Inc.; 2007.

Mai NguyenAbout the author: Mai Nguyen is an aspiring food scientist who received her B.S. in biochemistry from the University of Virginia. She hopes to soon escape the bench in pursuit of a more creative and fulfilling career.

Read more by Mai Nguyen

Science of Marinades

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Chicken Tikka Masala, Beef Bulgogi, and Ceviche all have one thing in common: each protein is marinated, which contributes to the development of flavors and textures in the final dishes. The use of marinades is common across all cultures, and can provide a unique kick to food when done correctly.

Rostbrätel: marinated cutlet of pig neck. Photocredit: (Sebastian Wallroth/Wikimedia Commons)

What is marination?

Marination is the process of immersing foods in a liquid often made with oil, seasonings, and an acid or enzymatic component, to flavor and tenderize food. This liquid is called a marinade, and the term originally came from the use of seawater to preserve meat. The roots of the word are derived from the Latin word for sea (mare) [1].

Why is marination useful?

To understand the importance of marination, we must first address the components of raw meat. Consider tough, lean cuts of meat such as shank or flank. Meat toughness is related to the collagen and elastin fiber content in its connective tissues. One way to tenderize lean meat is with moist heat, as this breaks down stiff collagen proteins into soft, soluble gelatin [2]. Gelatin is responsible for that silky, falling-apart texture and mouthfeel [3]; this can be achieved with braising and stewing, where meat is simmered in liquid at a low temperature, allowing collagen to dissolve starting at 160º F. However, this conversion process can take some time, even up to 72 hours. Another reason to pre-tenderize meat before cooking is to prevent dried out meat: moisture is lost when heat is applied (despite being cooked in liquid).

This is where marination comes into play, as it provides another opportunity for protein breakdown. This method can thus shorten subsequent cooking time as well as minimize moisture loss as less heat is needed to “cook” the meat. Two types of marination include acidic and enzymatic marination, which both help break down the connective tissue in the meat.

Acidic marination

Acids, such as lemon juice or vinegar, work by denaturing proteins through disruption of hydrogen bonds in the collagen fibrils. Adding alcohol can also supplement the penetration of acid marination since fats present in meat are soluble in alcohol [4]. Beer and wine thus make great marinades, and they also confer their own tenderizing agents (tannins). Be careful not to overmarinate the meat, as prolonged exposure to acid can cause it to become tough. This occurs because after the proteins are denatured, they tighten as water content decreases [5]. Some marinades involve milk or yogurt since they have lower acid content.

Shrimp Ceviche, a dish that uses acidic marination. Photo Credit: Carlos Lopez (cloalpz/Flickr)

Enzymatic marination

Enzymes increase the rate at which cellular reactions occur, and certain enzymes help attack the protein networks of tough meat. Proteolytic enzymes such as fungal amylase (in legume seeds) and protease (in ginger) help break down muscle fiber protein into its constituent amino acids. Enzymes from tropical plants such as bromelain (in pineapple), papain (in papaya) and ficin (in latex of fig tree) break down collagen and elastin [4]. In fact, natives of pre-Columbian Mexico used to wrap their meat in papaya leaves before cooking since they found that it increased tenderness [6]. However, be sure to monitor the time of marination, for the enzymes can completely digest meats if they sit for too long.

Papaya contains papain, a proteolytic enzyme. Photo credit: Tatiana Gerus (Tatters/Flickr)

Adsorption

Another factor to take into account is the amount of contact the meat has with the marinade. Marination is a process of adsorption, where the marinade adheres to the outer surface of the meat rather than absorption, where it would penetrate all the way through [7]. This has resulted in some controversy over whether acidic and enzymatic marinades actually tenderize meat or not, but there are ways to alleviate this problem. It may be helpful to use thinner slices of meat to enhance the marinade penetration and reduce marination time. For thicker cuts, marinades can be injected to increase contact surfaces. Adding salt also helps, as it first draws out liquid by osmosis; then the resultant brine is reabsorbed into the meat while breaking down muscle structure. The brine draws flavors further down below the surface [8]. Fat such as oils are also useful to transfer fat-soluble flavors from the seasonings into the meat.

In general, tender cuts of meat should not require as much marination time as tougher cuts, and fish require even less time. Marinated meats should also be refrigerated to prevent harmful bacterial growth. Although it may seem a hassle to prepare ingredients for a marinade and remember to apply it to the meat for a certain time beforehand, the results can be well worth the wait.

References cited

  1. Some Surprising Facts About Marinades and the Origin of the Word. CulinaryLore.
  2. Collagen. About Food.
  3. Science of Slow Cooking. Science of Cooking.
  4. Juáres, M., Aldai, N., López-Campos, Ó., Dugan, M., Uttaro, B., Aalhus, J. Beef Texture and Juiciness. Handbook of Meat Processing. January 2012.
  5. Marinating Meats. Allrecipies.
  6. Alarcón-Rojo, A. Marination, Cooking, and Curing: Applications. Handbook of Poultry Science and Technology, Secondary Processing. February 2010.
  7. Saucy Science: Exploring the Science of Marinades. Scientific American.
  8. The Food Lab: More Tips For Perfect Steaks. Serious Eats.

Catherine HuAbout the author: Catherine Hu is pursuing her B.S. in Psychobiology at UCLA. When she is not writing about food science, she enjoys exploring the city and can often be found enduring long wait times to try new mouthwatering dishes.

Read more by Catherine Hu

 

The Science of Pie 2014: Video Highlights

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The Science of Pie 2014: Video Highlights

June 1, 2014

At the Science of Pie, the world’s first scientific bakeoff, the students of the Science & Food undergraduate course presented results from their final projects in poster format and their pies for taste testing. These pies had to be cooked in one hour and were the summation of all that the students had learned from their pie experiments in the class. Throughout the quarter, the students were challenged to perform a scientific investigation of apple pie and vary different features of the pie such as shape, butter size, and moisture.

The contest was judged by Lena Kwak (of Cup4Cup) and Dave Arnold (of Booker and Dax, the Museum of Food and Drink, and the Cooking Issues Podcast) who were our featured speakers for the 2014 Public Lecture Harnessing Creativity. They were joined by Nicole Rucker (Pastry Chef, Gjelina Take Away), Jonathan Gold (Food Critic, LA Times), Dr. Paul Barber (Associate Professor of Ecology and Evolutionary Biology, UCLA), and Dr. Rachelle Crosbie-Watson (Associate Professor of Integrative Biology and Physiology, UCLA).

The judges had wise words for the students.

Lena Kwak described how she judged the pies.

“With each of the projects we saw today, there were a considerable amount of variables not considered, but the saving grace …was when I tasted their pies.”

Nicole Rucker talked about what makes an award wining pie

“Jonathan and I both know that from Judging Pie Contests, … that you can see a good pie from literally across the room.”

Dr. Paul Barber spoke to the balance of science and pie making:

“No matter how much scientific testing you do, there’s still just this underlying art to making a really good pie.”

Check out some our featured pies from the 2014 contest.

Honorable Mention Pie

Alexis Cary & Matthew Copperman (Team On the Road)

Perfectly Unsoggy Apple Pie

Best Scientific Pie

Christina Cheung, Tori Schmitt, and Elliot Cheung (Team Pretty Intense Pie Enthusiasts)

Beer Crust Apple Pie

Best Overall Pie & People’s Choice Pie

Alina Naqvi & Ashley Lipkins-Scott (Team Apple Queens)

Crumbalicious Apple Pie

Check out our written recap here !

See the whole Video!

Beer

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Celebrating St. Patrick’s Day with a frosty glass of beer? Before taking that first sip, consider these quick facts about the science behind the many complexities in beer flavors. Now that’s something to raise your glass to! Read more

Physiology of Foie Gras

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Photo Credits: (flickr/Ulterior Epiculture)

Photo Credits: (flickr/Ulterior Epicure)

Decadent, diseased, silky, sinful. The adjectives that follow foie gras range from the disgusting to the luxurious. The fattened liver of a duck or goose polarizes people, and there seems to be no middle ground wherein a person can both enjoy foie gras and ethically question it. Because it is such a controversial food, the discourse surrounding it is often steeped in emotion, but the best way to make an informed, fact-based decision is through science. Here we will examine physiology, pathology, and a bit of genetics regarding waterfowl and foie gras in an attempt to promote overall awareness of what we eat (or don’t eat).

Foie gras is French for fatty liver, and that is exactly what it is. The liver of a bird, usually a duck or sometimes a goose, that has been force-fed to the point of having a fat, enlarged liver. The liver must weigh more than 300g for ducks, and 400g for geese to legally bear the name foie gras in France. [1] Force-feeding is typically done through a practice called gavage, wherein a long tube is inserted into the bird’s mouth and throat up to three times a day for 3-10 days. French rural code L654-27-1 states that “Foie gras belongs to the protected cultural and gastronomical heritage of France.”[2] Currently, the farming of animals to produce foie gras is banned in 22 EU nations, but not its sale or import. In California, the sale of foie gras was banned in 2004, the ban was lifted in early 2015 by a federal court, and the lifting of that ban is currently being appealed. [3] Needless to say, it’s a very complicated issue.

Photo Credits: (flickr/Pickled newt)

Photo Credits: (flickr/Pickled newt)

Foie Gras Physiology

Many bird species, including ducks and geese, eat prey much wider than the diameter of their esophagus. Consequently, the inner diameter of the upper part of the esophagus is comparatively larger than in mammals. [4] Also unlike mammals, the upper esophagus is not circled by cartilaginous rings, which explains how birds swallow whole, live fish with ease. In humans, the upper esophageal sphincter is a high-pressure zone situated between the pharynx and the cervical esophagus. The sphincter is composed of muscle, cartilage, and bone, [5] and thus is much more rigid than the upper esophagus of a waterfowl. Most birds species posses an “outpouching” of the esophagus, known as the crop. It also allows the birds to store large amounts of food before sending it along to the stomach for digestion. [4]

Another important difference in human and duck anatomy is the trachea. In humans, food and air start along the same path in the mouth, then the trachea (or windpipe) branches off at the back of the throat where the epiglottis prevents food from entering the trachea and channels swallowed food along its proper route, the esophagus. Try to force something past the epiglottis, and you trigger the unpleasant pharyngeal reflex, or gag reflex. Certainly a gavage would trigger this in a human, which is one reason why images of force fed birds make us so uncomfortable. Foie producers say if the procedure is carried under proper conditions, the gavage does not block the upper respiratory tract as the birds’ tracheas and esophaguses are completely separate, [6] and thus they do not gag or feel discomfort as a human would. However, foie gras critics rebuke that this is a ridiculous excuse, and that the birds are clearly harmed by the gavage.

Ducks and geese are sometimes reported to be panting when observed in a foie-farm. But before we assume they do so because they’re in distress, we should keep in mind that like a dog, panting in birds is a thermo-regulatory reflex. [4] Humans have sudoriferous glands (sweat glands) that discharge sweat to take care of latent heat, but birds do not. They regulate body temperature by opening their beaks and panting to cool down. Researchers have examined whether other avian behaviors are indicators of distress, like avoidance behavior, elevated heart rate, or elevated cortisol (stress hormone) levels. They report that force-feeding does not stress the birds more than typical capture and handling does. [1] [Side note: Most of this research was conducted by the same group of scientists from the French National Institute for Agricultural Research, so it would be helpful to have experiments performed by more organizations.]

Photo Credits: (flickr/Jeremy Couture)

Photo Credits: (flickr/Jeremy Couture)

Pathology

In mammals, hepatic steatosis (fatty liver) is a pathological condition. Human fatty liver occurs when there is an imbalance of fat uptake and export in the liver, most often caused by alcoholism, malnutrition, obesity, or diabetes. On its own, hepatic steatosis is not harmful and can be reversed, but if not addressed with dietary and lifestyle change it can develop into cirrhosis, wherein the healthy liver tissue is replaced by scar tissue, or necrosis (tissue death). Indeed, foie gras in a human is a disease. [7]

Certain metabolic adaptations in migratory birds and fish cause a natural hepatic steatosis, and proponents of foie gras use this observation to argue that the condition is not pathological in those species. These animals must compile large energy stores for their migrations, and they do so by ingesting carbohydrates and storing the energy as fat, a process called lipogenesis. [8] Foie producers posit that they are simply exploiting the incredible lipogenetic abilities of the fowl liver. The human liver does no more than 30% of our entire bodies’ lipogenesis, as our adipose tissue carries most of the workload. [9] By contrast, the avian liver performs the vast majority of their lipogenesis, up to 96% of it in some species. [10] To further their argument that their birds are not diseased, foie farmers assert that it is in their best interest to avoid producing diseased livers, as they are of no commercial value.

Photo Credits: (flickr/Jay Tong)

Photo Credits: (flickr/Jay Tong)

Genetics of the Muscovy Duck

In addition to the anatomical and physiological aspects of waterfowl that may make the production of foie gras seem less cruel, a look into the breed may provide further insight. Foie gras is made from the liver of the Moulard duck, which is the product of a female Pekin artificially inseminated with the sperm of a male Muscovy duck. [1]The Moulard, or “mule duck” genotype is not present in the wild, and like other hybrid species, it is sterile. Therefore, the animals themselves cannot breed more baby Moulards.

Muscovies are non-migratory, [11] so unlike migratory species, in natural settings they do not gorge themselves to put on extra fat to carry them through long periods of physical exertion with no breaks to replenish energy. It might seem like they would be a poor choice for duck farming, but they are prized for their well-flavored, lean meat.

Pekin ducks on the other hand have many of the characteristics of migratory species. They are naturally gregarious and clump themselves together whether or not they have space to roam. [11] Years of breeding have made them very plump and small-winged, and thus they no longer migrate. However, their inner organs and basic metabolism still maintain characteristics of migratory waterfowl. The moulard thus exhibits the more desirable behavioral features of the two species. Like muscovies, they have no migratory instincts, so they are easy to farm-raise. But they retain all of the anatomy and metabolism of Pekins that naturally make them want to gorge and store energy as fat.

Photo Credits: (flickr/Taylor149)

Photo Credits: (flickr/Taylor149)

In this physiological context, gavage and foie gras might not be as tortuous as some imagine it to be. Even with this information, some people may still feel uncomfortable with the idea of force-feeding, and that is perfectly reasonable. If we want to eat foie gras entirely guilt-free, perhaps we should support the production of “humane” foie gras, where the animal is left to gorge on its own as if it were preparing for migration. Examining foie gras through a scientific lens teaches us to evaluate the animal body for its natural capabilities, but science does not always give us clear answers as to what is morally right. Regarding foie gras, the jury is literally still out.

References Cited

  1. Guémené, Daniel, Gérard Guy, Jérôme Noirault, Nicolas Destombes, and Jean-Michel Faure. “Rearing Conditions during the Force-feeding Period in Male Mule Ducks and Their Impact upon Stress and Welfare.” Animal Research 55.5 (2006): 443-58. Web.
  2. “Legifrance – Le Service Public De L’accès Au Droit.” Code Rural Et De La Pêche Maritime. N.p., n.d. Web. 19 Feb. 2015
  3. McClurg, Lesley. “The Legal Battle Over Foie Gras Continues.” – Capradio.org. Capital Public Radio, 9 Feb. 2015. Web. 19 Feb. 2015.
  4. Guémené, Daniel, Gérard Guy, Jacques Servière, and Jean-Michel Faure. “Force Feeding: An Examination of Available Scientific Evidence.” Artisan Farmers Alliance (n.d.): n. pag. Artisanfarmers.org. Web.
  5. Kuo, Braden, and Daniela Urma. “Esophagus – Anatomy and Development.” GI Motility Online (2006): n. pag. Web.
  6. http://onlinelibrary.wiley.com/store/10.1111/j.1740-8261.1991.tb00087.x/asset/j.1740-8261.1991.tb00087.x.pdf?v=1&t=i5inm4hl&s=a129cb6b04b350dfd5778a83eaaea1f2f0fb02a0
  7. Jaeschke, Hartmut, Jaspreet S. Gujral, and Mary Lynn Bajt. “Apoptosis and Necrosis in Liver Disease.” Liver International 24.2 (2004): 85-89. Web.
  8. Pilo, B., and J.c. George. “Diurnal and Seasonal Variation in Liver Glycogen and Fat in Relation to Metabolic Status of Liver and M. Pectoralis in the Migratory Starling, Sturnus Roseus, Wintering in India.” Comparative Biochemistry and Physiology Part A: Physiology 74.3 (1983): 601-04. Web.
  9. Timlin, Maureen T., and Elizabeth J. Parks. “Temporal Patterns of De Novo Lipogenesis in the Postprandial State in Healthy Men.” The American Journal of Clinical Nutrition 18.1 (2005): 35-42. Web.
  10. Desmeth, M., M. Messeyne, G. Schuermans, J. Vandeputte-Poma, and F. Vandergeynst. “Effect of Age and Diet on the Fatty Acid Composition of Triglycéridesand Phospholipids from Liver, Adipose Tissue and Crop of the Pigeon.” The Journal of Nutrition 111 (1980): n. pag. Web.
  11. Lopez, Kenji. “The Physiology of Foie: Why Foie Gras Is Not Unethical.” Serious Eats. N.p., 16 Dec. 2007. Web. 18 Feb. 2015.

Elsbeth SitesAbout the author: Elsbeth Sites is pursuing her B.S. in Biology at UCLA. Her addiction to the Food Network has developed into a love of learning about the science behind food.

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Coffee Brewing Methods

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Gone are the days where all that was needed to make a cup of brewed coffee was an auto-drip machine and a paper filter. Coffee shops now have glass siphons lining the counter, looking as if they came straight from a chemistry lab. Baristas can be seen meticulously pouring water from a swan necked kettle into a ceramic funnel, which slowly drips coffee into a cup sitting on a scale. There is even a ready-to-serve cold brew option that was prepared the night before. These days, coffee shops seem to be stocked with new tools for brewing the delicious caffeinated beverage. With the resulting brews varying in flavor, why stick to just one method? Each apparatus has a different extraction process and requirements for grind coarseness, heat, and time.

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A cup of coffee. Photo Credit: (Julius Schorzman/Wikimedia Commons)

For all brewing methods, coffee must first be ground; then its soluble components must be dissolved in water, so they are released into the resulting brew. It is suggested to grind coffee right before brewing, since the process releases flavor as well as results in a higher perceptions of aromas; these aromas consist of highly volatile compounds which can evaporate into the air over time [1]. The grind level and particle size also play important roles in the taste of the final cup of coffee. If the grind is too fine, bitter coffee can result from over-extraction of chlorogenic acids; if the grind is too coarse, a weaker brew may result from the decreased surface area [2].

Coffee brewing is generally classified under three types: decoction, infusion or steeping, and pressure methods.

Decoction: Siphon

In decoction, ground coffee is in contact with high temperature water for a period of time, causing a more intense extraction [2]. Siphon, or vacuum brewed coffee, is an example of this method. Since many variables can be controlled, the coffee can be evenly extracted over a period of 45 seconds to 1 minute [3].

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Siphon. Photo Credit: Janne Moren (JanneM/Flickr)

A siphon consists of two glass chambers arranged vertically. Near boiling water is added to the bottom chamber with a heat source underneath. When the water is heated past its boiling point (212 °F or 100 °C), the heat source transfers energy to the water and produces vapor, or steam. Eventually, the pressure created from the gas exceeds that of the atmospheric pressure in the siphon. In order to create more room for itself in the bottom chamber, the gas forces the remaining liquid into the upper chamber. The coffee grounds are added at this point and stirred. The heat source maintains a constant pressure, keeping the brew in the upper chamber. Once the brew is complete, the heat source is removed and the water vapor condenses back into liquid form. Since liquid takes up less volume than gas in the bottom chamber, a negative pressure void is created that is then equalized by the brew flowing down [4].

Infusion/Steeping: Chemex

An infusion involves steeping coffee in water before filtration, and creates a milder brew with more acidity [2]. An example is the Chemex, which is a funnel shaped apparatus with a pour over filter cone attached to a decanter. This is similar to a typical auto-drip coffeemaker where the coffee is steeped and dripped through a paper filter. However, the Chemex has some advantages, including control over water temperature, infusion time, and pouring technique. The filter used is also thicker, so the grounds are able to steep in the water and drip out more slowly. More flavor compounds are released, resulting in a clean tasting brew with “bright” and “high” notes [5].

Chemex. Amy Roth (minimallyinvasivenj/Flickr)

Chemex. Amy Roth (minimallyinvasivenj/Flickr)

To prepare coffee with the Chemex, a medium to medium-coarse grind is placed on top of a pre-rinsed filter. Hot water is poured from a swan neck kettle (the narrow spout maximizes pour control) in a circular motion. As the first pour touches the coffee grounds, it degasses and carbon dioxide (CO2) is released, resulting in bubbles and puffed up grounds. This is called a “bloom,” and this process influences the flavor and aromas of the brew, including increased acidity if the bloom time proceeds for too long [6]. The reasoning behind this is that when CO2 reacts with water, it produces carbonic acid. Interestingly, lighter roasted coffee beans retain more CO2 than darker roasts [7].

CO2 (aq) + H2O (aq) « H2CO3 (aq)

Once the gas is released, the water starts to dissolve the solubles in the coffee grind, which are responsible for many of the flavor components. As the brew starts to drip into the decanter, additional water is poured in the same circular motion to make sure that the grounds are constantly replenished with fresh water [6]. The grounds must always be immersed to maintain a constant temperature for the brew and to keep the chemical reactions going. This method also creates a strong osmotic pressure to extract the coffee concentrate from the grounds: since there are more coffee solutes in the grind and less in the watery environment, the solutes will want to escape through the semi-permeable cell membranes of the coffee beans. However, since water is continuously poured over the surface of the grounds, there is a possibility of over extraction from the top layer [7].

Pressure: Moka pot

Unlike decoction and infusion, this method involves water being forced through grounds with high pressure and heat, similar to the style of espresso [2]. The Moka pot consists of a bottom chamber with water, a metal filter filled with ground coffee, and a screw-on upper chamber.

Moka pot during extraction process. Photo Credit: (RyAwesome/Flickr)

Moka pot during extraction process. Photo Credit: (RyAwesome/Flickr)

Similar to the siphon, a heat source causes the water in the bottom chamber to form steam. However, instead of mixing the water with coffee for steeping, the water vapor pushes the water through the coffee grounds and the brew emerges out of the top portion as a gurgling sound is made. The bottom chamber is not filled all the way with water to ensure an air gap for pressure to form. In fact, in case the pressure in the bottom chamber gets too high, there is a safety valve on the lower chamber that lets the air out to keep the apparatus from exploding.

With all of these different options, brewing coffee is now more of an art form than just a way to obtain caffeine. Whether you use a Moka pot at home or have a barista prepare a cup using a pour over method, you can be sure that each resulting brew will be far from tasting the same.

References cited

  1. Akiyama, M., Murakami, K., Ohtani, N., Iwatsuki, K., Sotoyama, K., Wada, A., et al. Analysis of Volatile Compounds Released During the Grinding of Roasted Coffee Beans Using Solid-Phase Microextraction. Journal of Agricultural and Food Chemistry. July 2013; 51: 1961–1969.
  2. Sunarharum W, Williams D, Smyth H. Complexity of coffee flavor: A compositional and sensory perspective. Food Research International. March 2014; 62: 315-325.
  3. How to Brew Coffee in a Siphon or Vacuum Brewer. Seriouseats.
  4. Vacuum Pots: The Science Behind the Method. Casa Brasil Coffees.
  5. A Beginners Guide to Pour Over Coffee Brewing. Prima Coffee.
  6. What is the Bloom and Why Should You Care? The Roasters Pack.
  7. Coffee Science: How to Make the Best Pourover Coffee at Home. Seriouseats.

Catherine HuAbout the author: Catherine Hu is pursuing her B.S. in Psychobiology at UCLA. When she is not writing about food science, she enjoys exploring the city and can often be found enduring long wait times to try new mouthwatering dishes.

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Lavender

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Lavender Cream

Lemon curd pudding lavender cream
Photo credit: Sue O’ Bryan (Foodlander/Flickr)

How does sipping a cup of lavender tea with honey sound? Soothing? Fragrant? Then imagine stumbling upon an open field of lavender flowers. The lavender plant, genus Lavandula, comprises 39 flowering plant species, all of which are easily recognized by that trademark color and signature fragrance. The most popular species of lavender is L. angustifolia, commonly known as English lavender and lauded for having the sweetest fragrance among lavender plants. Lavender flowers are primarily grown in order to extract the essential oil for both medical and culinary uses.

The distinctive purple flower is popular for its calming abilities, extensively used in aromatherapy alongside other herbs. Lavender is additionally famed for its healing properties. French chemist, René-Maurice Gattefossé realized the usefulness of lavender oil as a healing essence when he plunged his burned arm into a tub of liquid containing lavender oil, later noting quick tissue regeneration with little scarring [1,2]. Following Gattefossé’s observation and subsequent experiments using lavender oil in military hospitals during World War I, lavender is also used today as an antiseptic and anti-inflammatory [1]. As an herb, lavender of course has a dedicated fan base in the culinary world; the fragrant flower is the star of recipes such as lavender cake, lavender shortbread, and even lavender and honey roasted chicken.

Analysis of lavender oil reveals the primary compounds responsible for the scent are linalyl acetate and linalool (pronounced lin-ah-low-awl). Both have been cited to contain various pharmacological properties that aid in relaxation, such as anti-anxiety, anti-depressant, [1] and relaxant of vascular smooth muscles [3].

Minor volatile components that contribute to the scent of lavender essential oil include (E)-β-ocimene, (Z)-β-ocimene, terpinen-4-ol, 1,8-cineole, camphor, and limonene.

Minor compounds

But make no mistake. There’s nothing “minor” about these compounds when it comes to lavender flavor. According to the flavor network by physicist Albert-László Barabási, North American and Western European cuisines like to pair ingredients that share many flavor compounds. Camphor confers a woody, evergreen scent and is one of the primary volatile compounds in dried rosemary leaves; this makes lavender and rosemary a comforting combination. Further, linalyl acetate, linalool, and many of the minor volatile components of lavender oil can also be found in lemon peels and lemon essential oil [4]. Lavender and lemon are such celebrated culinary companions that the two are practically best friends.

Want to try cooking with lavender for the first time? Relax; it’s not as challenging as it seems. Just take a deep breath and try out this simple lavender sugar recipe.

References cited

    1. Tankeu SY, Vermaak I, Kamatou GPP, Viljoen AM. Vibrational spectroscopy and chemometric modeling: An economical and robust quality control method for lavender oil. Industrial Crops and Products, 2014; 59: 234-240.
    2. René-Maurice Gattefossé. Oils and Plants. Accessed 2014, December 21.
    3. Koto R, Imamura M, Watanabe C, Obayashi S, Shiraishi M, Sasaki Y, Azuma H. Linalyl acetate as a major ingredient of lavender essential oil relaxes the rabbit vascular smooth muscle through dephosphorylation of myosin light chain. Journal of Cardiovascular Pharmacology, 2006; 48(1): 850-856.
    4. Oboh G, Olasehinde TA, Ademosun AO. Essential oil from lemon peels inhibit key enzymes linked to neurodegenerative conditions and pro-oxidant induced lipid peroxidation. Journal of Oleo Science, 2014; 63(4): 373-381.

Alice PhungAbout the author: Alice Phung once had her sights set on an English degree, but eventually switched over to chemistry and hasn’t looked back since.

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