Wasabi Receptors and Smart Sushi Labels

By Ashton Yoon | March 27, 2017 9:52 pm


Researchers at UCSF have elucidated the structure of the receptor that makes our sensory nerves tingle when we eat wasabi.

As this receptor is important in our perception of pain, knowing its shape should help in the development of new pain medications. A company called Thinfilm, developed very thin, electronic label that tracks vital information about certain foods at each stage of the supply chain. This way, foods like sashimi salmon can have its temperature monitored from the warehouse to the grocery store, supplying information the consumer can use to decide whether to buy it.

The label offers a more accurate expiration date which could help decrease food waste and the number of cases of food-borne illnesses.

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The Secret in Your Sushi

By Ashton Yoon | March 27, 2017 9:49 pm

(Photo Credit: Oceana/Jenn Hueting)

Dining out or shopping in a grocery store are seemingly straightforward: as the consumer, you make your selection and exchange money for goods. These interactions are based on an implicit trust that you get what you paid for. However, in recent years consumers have begun to demand more transparency with reports of mislabeled seafood at retailers and restaurants being greater than 70% in some instances [1].

Seafood is one of the most traded food items in the world, with approximately 4.5 billion people consuming fish as at least 15% of their source of animal protein [2]. The U.S. is the second largest consumer of seafood in the world behind China and with the recent health recommendations from the American Heart Association elucidating the benefits of fish consumption, sales of this commodity have reached an all-time high [3]. Increased awareness of the environmental burdens of the meat industry have further contributed to this move towards more seafood proteins [4]. The opportunities for seafood mislabeling have consequently increased.

A recent study performed by the Department of Ecology and Evolutionary Biology at UCLA sampled from 26 sushi restaurants in Los Angeles from 2012-2015. Led by Demian A, Willette and Sara E. Simmonds, this study found that a whopping 47% of samples were mislabeled. Similarly, From 2010-2012, Oceana, the world’s largest international ocean conservation organization, conducted a study investigating the prevalence of seafood fraud on a nationwide level. They collected 1,200 samples from 674 restaurants and markets in 21 different states and found that 33% of the samples were mislabeled. Figure 1 depicts a map generated from this study and the respective amount of mislabeling for each state sampled [3].

The types of substitution vary, often substituting cheaper fish such as tilapia for more expensive fish such as grouper, cod, and snapper [3]. Among the different types of fish sampled in UCLA’s four-year study, it was found that all sushi fish types, except Bluefin, tuna were mislabeled at least once. Halibut and red snapper samples were mislabeled 100% of the time [1].


Figure 1: National seafood fraud testing results (Photo Credit: Oceana)

UCLA and Oceana’s studies relied on DNA barcoding technology to elucidate the true identity of the sushi samples. DNA is the genetic blueprint of life, with each organism having its own unique genetic code that can be used in its identification. A DNA barcode is a specific DNA sequence within the genome that is used to identify a species. The sequence chosen is one that is conserved throughout species generations but contains detectable levels of variation between species to serve as a species identifier [5]. The specific sequence used was a fragment of the cytochrome c oxidase I (COI) mitochondrial gene that enables species to be identified without relying on any morphological indicators such as color or shape [4].


Figure 2: DNA barcoding process. (Photo Credit: Bio-Rad)

The basic process of DNA barcoding is outlined in Figure 2. First, a sample of the fish, which is approximately the size of an eraser on the end of a graphite pencil. Next, the DNA is extracted. This is achieved by the addition of buffers that both aid in breaking the cell membrane (which allows for the release of DNA) and denaturing the DNA [5], which involves the unfolding of its double-stranded helix structure and separation into two single strands, exposing the base pairs and making them available for replication.

Now that the fish DNA is isolated, the COI gene must be replicated enough times to in order to be sequenced, as well as visualized on a gel. This process is called polymerase chain reaction (PCR) amplification. This is accomplished using primers, or small strands of DNA that are recognized by DNA polymerase, the enzyme responsible for DNA replication. The primers used are called “degenerate primers,” [5] because they have flexibility in several base positions [6], DNA polymerase is used to extend the primers and replicate the DNA, effectively amplifying the amount of COI gene present in the sample [5].


Figure 3: Scientists prepare fish samples for DNA barcoding. (Photo Credit: Oceana/Jenn Hueting)

A gel electrophoresis is then performed on the sample and a UV transilluminator allows visualization of the DNA banding patterns in each sample. The samples are then sent to a specialized sequencing facility that utilizes the PCR products with a reverse sequencing primer and compares the produced DNA sequences using an algorithm called Basic Local Alignment Search Tool (BLAST) that compares the samples to an established sequence database.

This produces a numerical value called the “E-value” that serves as an indicator of homology and is used in conjunction with the result of gel electrophoresis in the identification of each sample’s species [5]. Figure 4 contains an image featuring the DNA barcodes of different species of fish. Each DNA base (C, T, G, or A) is designated by a specific colored bar, which are lined up in sequence and produce a specific barcode. Therefore, color variation indicates which bases differ amongst the species shown [5].


Figure 4: DNA barcodes of different species of fish. (Photo Credit: Ibol Project)

Besides the inherent dishonesty, there are many other negative effects of seafood mislabeling. Ocean conservation programs rely on accurate labeling in their calculations and recommendations, which can be skewed with inaccurate accounts of what species are being caught and sold [1].

Additionally, honest fisherman and businesses suffer as their correctly labeled fish are unable to compete with the low prices of mislabeled fish. Consumer health is also another issue. For example, white tuna was substituted with escolar 84% of the time, which is linked to serious digestive problems and consequently is banned in Italy and Japan [3]. Mislabeling of pufferfish as monkfish has led to temporary neurological damage in some consumers in 2007 and a monkfish recall. Substitution among tuna species also led to elevated mercury levels in canned light tuna, which is usually recommended as a safer canned tuna for children and pregnant women [1].

How can DNA barcoding change the future of seafood mislabeling and the seafood industry? Although 90% of seafood in the U.S. is imported, only 1% is inspected for fraud [3]. If DNA barcoding is used as a regulatory measure, it has the ability to strengthen traceability and therefore liability.

Currently, it is difficult to pinpoint exactly where in the food chain the mislabeling occurs, whether it is at the restaurant, retailers, or even earlier in the supply chain [3]. By enforcing existing policies through inspectors, retailers, easy-to-use DNA barcoding kits, and a sense of accountability throughout the seafood supply chain, we can use science to move towards a resolution towards these fishy mislabeling practices.

References Cited:

  1. Willette, D.A., Simmonds, A.E., Cheng, S.H., et. Al. (2017). Using DNA barcoding to track seafood mislabeling in Los Angeles restaurants. doi: 10.1111/coni.12888.
  2. Bene, C., Barange, M., Subasinghe, R. et al. (2015). Feeding 9 billion people by 2050 – putting fish back on the menu. Food Security 7: 261-274.
  3. Oceana (2013). Oceana study reveals seafood fraud nationwide. Retrieved from http://oceana.org/sites/default/files/National_Seafood_Fraud_Testing_Results_Highlights_FINAL.pdf
  4. Wong, E.H.K., Hanner, R.H. (2008). DNA barcoding detects market substitution in North American seafood. Food Research International 41: 828-837.
  5. Tighe, D., Andrews, S., Brown, L. (2016). Generate a DNA barcode and identify species. Retrieved from http://slideplayer.com/slide/5768597/
  6. Linhart, C., Shamir, R. (2005). The degenerate primer design problem: theory and applications. J comput Biol 4: 431-56.


Ashton YoonAbout the author: Ashton Yoon received her B.S. in Environmental Science at UCLA and is currently pursuing a graduate degree in food science. Her favorite pastime is experimenting in the kitchen with new recipes and cooking techniques.

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Mind Control and Alternative Burgers

By Ashton Yoon | March 27, 2017 9:41 pm


“Given humankind’s long history of struggling to find food, it makes sense that people are highly motivated to hunt it down, and that we experience intense pleasure when we finally eat it.”

According to Lauri Nummenmaa, a neuroscientist at Aalto University in Finland, this evolutionary drive to secure food could also mean that fatty foods affect our neuronal activity. Researchers found a weight-dependent pattern in the opioid receptors of healthy weight versus morbidly obese women.

If you have burgers on the brain, take some time to wonder: Will alternatives to meat ever become mainstream?

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Chili Pepper Travels & Turmeric Medicinal Chemistry

By Science & Food | January 26, 2017 10:00 am


How obsessed with spicy are you? Ecologist Joshua Tewksbury from the University of Washington is willing to travel thousands of miles to Amboró National Park in central Bolivia just to answer one burning question: Why are chilies spicy? For those who prefer a different kind of spicy, a study in the Journal of Medicinal Chemistry can shed light on why turmeric is a better spice than a home remedy.
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By Science & Food | January 17, 2017 10:00 am

Guest post by Earlene Mulyawan

Whether it is adding chili flakes to top off your pizza, Tabasco to your omelet, chili oil to your ramen, there’s no doubt adding these condiments can add flavor intensity to all our dishes. Interestingly, the burning sensation is actually not a taste, since the sensation does not arise from taste buds. Capsaicin stimulates nerves that respond only to mild increases in temperature, the ones that give the sensation of moderate warmth [1]. Capsaicin sends two messages to the brain – intense stimulus and warmth. The burning sensation you feel when eating spicy food is due to the combination of these two messages.

What is the science behind all this magic? The answer to that is a supernatural compound capsaicin (or 8-methyl-N-vanillyl-6-nonenamide). Capsaicin is a common pungent molecule. It is found in capsicum fruits that are used in a variety of cuisines.


Figure 1: Chemical structure of capsaicin. Photo Credit: Essential Oil

Pure capsaicin is colorless, odorless, and crystalline-to-waxy solid at room temperature. The Scoville Heat Scale for pure capsaicin is about 16,000,000 SHU (Scoville Heat Units). SHU is a measurement of pungency. Ghost pepper is approximately 1,000,000 SHU; cayenne is approximately 40,000 SHU. Capsaicin is a hydrophobic molecule, meaning that it preferentially partitions into fatty environments. When consumed, capsaicin binds with pain receptors in the mouth and throat, which are normally responsible for sensing heat [2]. The taste buds on our tongue contain taste receptors. Taste buds sense tastants (taste molecules) and send the information from the tastants to the brain, where the molecule is processed as a certain taste. There are five main tastes: bitter, salty, sweet, sour and umami (savory) [3]. “Spicy” or “hot” is not sensed by our taste buds; instead, they are sensed by pain receptors, which are also found in the tongue. These receptors send pain signals via our nerve fibers to the brain, where it is perceived as a sensation of pain and heat.

But how does capsaicin give us the sensation of “tongue on fire”? Capsaicin is the active component of chili peppers that produces a burning sensation in any tissue it comes in contact with. How does this signal get conveyed? There are three classes of nerve fiber in our central and peripheral nervous system – the ‘C’ type of nerve fiber are the ones that are stimulated by capsaicin – specifically the molecule binds to the vanilloid receptors (VR-1, TRPV1) on the nerve endings of the C-fibers. These receptors are ligand-gated ion channels that are closed in the absence of capsaicin. When they are stimulated by capsaicin, they open and allow an influx of sodium and calcium ions, which initiate an action potential across the fibers. This action potential is what allows us to feel the burn. Normally, physical heat stimulates these receptors. However, capsaicin can also interact with these receptors and activate proteins that cause the same signal to be transmitted to the brain into thinking that it is being burned.

How often we consume spicy food can affect the sensitivity of these receptors. If you consume them too frequently you can essentially “kill” your receptors. This is one of the factors that contribute to different people having a different spice tolerance level. The other factor is genetics. Our vanilloid receptors can be mutated such that they are less susceptible to capsaicin. Thus, it can be implied that we can inherit our tolerance for spices and also why different cultures and genetic populations can have different spice tolerances.


Figure 2: TRPV1 receptor. Photo Credit: Wikipedia

Although chili can add some flavor and magic to our dishes, it can also be unpleasant and painful for some people who are not used to it. When chili becomes too hot or too painful to handle, dairy products can come to your rescue. Understanding the physical properties of capsaicin can help to explain why milk can help rescue you from the fire on your tongue.

Capsaicin has a long hydrophobic tail, which allows it bind with high affinity to protein receptors on the tongue, which have hydrocarbon side chains of their own. This fatty tail of capsaicin also allows the molecule to diffuse through cell membranes, making the burn more pervasive and persistent. While water may offer a temporary relief, it is not entirely effective because capsaicin oil and water do not mix. In fact, water will actually spread the capsaicin oil instead of soothing the burn. By contrast, milk contains proteins and fat globules that the capsaicin can partition into. For example, casein is a milk protein that has a higher affinity to capsaicin and can compete with our lipoprotein receptors, surrounding capsaicin molecules and relieving the burn.

Pretty cool.



References Cited:

[1]: http://www.scientificamerican.com/article/why-is-it-that-eating-spi/

[2]: Ann M. Bode and Zigang Dong. “The Two Faces of Capsaicin.” 15 April 2011.


[3]: http://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/sensation-and-perception-5/sensory-processes-38/gustation-taste-buds-and-taste-163-12698/

References Cited:

[1]: http://www.scientificamerican.com/article/why-is-it-that-eating-spi/

[2]: Ann M. Bode and Zigang Dong. “The Two Faces of Capsaicin.” 15 April 2011.


[3]: http://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/sensation-and-perception-5/sensory-processes-38/gustation-taste-buds-and-taste-163-12698/

What is the Flavor of Los Angeles?

By Science & Food | January 3, 2017 10:00 am

Guest post by Nessa Riazi


Photo Credit: Edible Geography

When thinking of an airy, sugary meringue, baked Alaska or pavlova may be the first words to come to mind, but smog? Not quite.

You may have heard of the term terroir which explores changes in flavors based on differences in geographical locale, but aeroir is a rather new phenomenon. How can one possibly explore the tastes of air– or rather air pollution? At the Center for Genomic Gastronomy, food scientist Nicola Twilley whipped up a simple solution for this fascinating question. Why not make smog-flavored meringues! Upon reading Harold McGee’s bible of food science– On Food and Cooking: The Science and Lore of the Kitchen– co-founder of the Center for Genomic Gastronomy, Zach Denfeld discovered that meringue foam is 90% air. Thus, emerged the ingenious idea of “harvesting” the air quality of various cities. In a quasi-sensory explosion for your taste buds, but more so a commentary on the politics behind urban pollution, Twilley and fellow scientists “harvested” air once the egg-white foam reached the ‘stiff peak’ stage.

The meringues were whipped up in various locations such as on rooftops, roadsides, and waterways.


Mobile smog chambers and rows of UV lights which ‘bake’ the smog. (Photo Credit: The Forager)

In the process of recreating smog conditions, scientists injected calculated amounts of precursor chemicals into a Teflon smog chamber, where UV light was shone to catalyze the chemical reactions that form smog. As each city contains unique precursor emissions, varying in weather conditions from temperature and humidity to precipitation, each geographical region thus has a uniquely flavored meringue. For instance, in recreating the smog of an agricultural setting, students combined “ammonia and amines from feedlot manure lagoons and other organic waste…[mono-nitrogen oxides] NOx and incompletely combusted hydrocarbon emissions from cars, power plants, and industry…” [1] Harold McGee describes how these chambers were constructed to replicate air pollution around the globe, drawing chemicals emitted from tailpipes, smokestacks, and feedlots [2]. Variations of smog can thus be created with the help of ultraviolet lights.

As scientists create meringues for various cities around the globe, we can better understand the how air quality and pollution can affect the flavor of foods we eat. The atmosphere in Atlanta is one of the worst air qualities, running alongside that of Los Angeles [1]. Ten percent of emissions consist of terpenes–which are chemicals that stem from organic matter, whether that be pine trees or green matter that is decaying [3].

In addition to these fascinating studies, the Center for Genomic Gastronomy also publishes the journal, Food Phreaking, which explores up and coming experiments within food science and examines the places where food, culture, and technology intersect. As technology becomes progressively more intertwined with everyday life, our experiences with food can reach new and fascinating heights. Could tasting the cloudiness and mugginess of a smog meringue be the recipe for combatting air pollution?


References Cited:

[1] Smog Tasting: Four Years of Tasting Unexpected Ingredients. The Center for Genomic Gastronomy with Nicola Twilley. The Forager Magazine.http://www.theforagermagazine.com/4/7

[2] McGee, Harold. The Flavor of Smog. Lucky Peach Magazine. http://luckypeach.com/the-flavor-of-smog/

[3] Twilley, Nicola. Smog Meringues. Edible Geography: Thinking Through Food. http://www.ediblegeography.com/smog-meringues/ 30 May 2015.



The Science of Perfect Citrus Suprême

By Ashton Yoon | December 6, 2016 10:00 am

Photo Credit: Catie Baumer Schwalb (Pitchfork Diaries)

“Suprême” refers to the classic culinary technique of removing the flesh of citrus from the pith, or the white spongy layer in between citrus segments composed mainly of pectin and cellulose. Removing the pith, which is characterized by a distinctly bitter flavor, enhances the perceived sweetness in citrus fruit [1]. Though “suprême” may sound like a fancy-schmancy technique reserved for the finest of dining, citrus suprême can be found in common everyday foods such as mandarin orange slices on salads and garnishes in cocktails.

Classic citrus suprême is made by cutting off the top and bottom of the fruit, removing the pith with a knife, and cutting each segment out from between the membrane. However, this produces a lot of waste, as it is not possible to completely clean the pith of the fruit. It is also not efficient for large-scale industrial processing. Solution: pectinase.


Figure 1: The leftover pith waste from citrus supreme. Photo Credit: The Cherry Share

Pectinase is a general term for an enzyme that breaks down pectin, or the polysaccharide contained in plant tissue [2]. I set out to test the efficacy of pectinase in my own kitchen. I used the pectinase Pectinex Ultra SP-L, a polygalacturonase that is derived from the fungus Aspergillus Aculeatus [3]. Using a recipe from Chef Steps, I proceeded with the following protocol:

Recipe for Citrus Suprême [3]:

250g Citrus (About ½ pound citrus, or about 2 tangerines)

250g Water (About 1 cup water)

2.5g Pectinex Ultra SP-L (About ½ teaspoon)


Photo Credit: Ashton Yoon

Place Peeled citrus, water, and Pectinex in a bowl.


Photo Credit: Ashton Yoon

Refrigerate for about 2 days. Rinse segments in water.


Photo Credit: Ashton Yoon


Voila! Perfect citrus supreme.


Photo Credit: Ashton Yoon

To speed up the reaction you can heat up the solution to 104°F/40°C for 30 minutes [4]. However, because heat treatment is usually associated with nutrient degradation, this will likely lead to the partial deterioration of some nutrients in the citrus fruit.

Pectinases degrade the pectin in citrus pith by cleaving the bonds between the pectic polysaccharides. All three major types of pectin contain D-galacturonic acid, which is the target for polygalacturonase, the enzyme present in Pectinex Ultra SP-L. By hydrolytically cleaving the alpha 1,4-glycosidic linkages within the D-galacturonase backbone, polygalacturonase breaks down the structure of pectin [2]. The enzymatic breakdown of pectin, which is one of the main structural components of the pith, can explain why we are able to wash away the remains of the pith to easily make citrus suprême.


Figure 2: The reaction mechanism of polygalacturonase. (Pedrolli, D.B., Monteiro, A.C., Gomes, E., & Carmona, E.C., 2009)

In addition to citrus suprême, pectinases have many other industrial applications, including in the juice and wine industry. The utilization of pectinases enhances how much juice can be extracted from the fruit pulp, which ultimately increases yields and profits; pectinases also make processing more efficient and clarifies the juice to create a product with fewer solids that also looks more appealing too [5]. Taken together, pectinases contribute to the production of products that are more visually appealing from citrus supreme to juices and wines; they also help to reduce waste in food and beverage production to promote more sustainable processing in the food industry.


References Cited:

  1. Ni, H., Yang, Y. F., Chen, F., Ji, H. F., Yang, H., Ling, W., & Cai, H. N. (2014). Pectinase and naringinase help to improve juice production and quality from pummelo (citrus grandis) fruit. Food Science and Biotechnology, 23(3), 739-746. doi:10.1007/s10068-014-0100-x
  2. Pedrolli, D. B., Monteiro, A. C., Gomes, E., & Carmona, E. C. (2009). Pectin and pectinases: Production, characterization and industrial application of microbial pectinolytic enzymes. The Open Biotechnology Journal, 3(1), 9-18. doi:10.2174/1874070700903010009
  3. Cooking Issues (2010). Enzymatic Peeling. Retrieved from http://www.cookingissues.com/2010/03/23/enzymatic-peeling-hell-yes/
  4. Chef Steps (2012). Perfect citrus supreme. Retrieved from http://www.chefsteps.com/activities/perfect-citrus-supreme
  5. Sharma, H.P., Patel, H., Sugandha, S.P. (2010). Enzymatic extraction and clarification of juice from various fruits – a review. Critica; Reviews in Food Science and Nutrition.

Ashton YoonAbout the author: Ashton Yoon received her B.S. in Environmental Science at UCLA and is currently pursuing a graduate degree in food science. Her favorite pastime is experimenting in the kitchen with new recipes and cooking techniques.

Read more by Ashton Yoon


Turkeys: To brine or not to brine?

By Mai Nguyen | November 22, 2016 10:02 am

Photo credit: Flickr user camknows

Amidst the assortment of homemade pies and pillowy mashed potatoes, a moist, flavorful turkey is the hallmark of any traditional Thanksgiving. We’ve all been guilty of it though—feigning enjoyment while choking down tough, dry turkey that can’t be salvaged with even the most decadent of gravies. Brining offers a magic solution to your Thanksgiving turkey woes.

Brining is a simple technique that can promise your turkey a coveted, juicy tenderness. To brine a turkey, you immerse it in a solution of 3-6% salt by weight, for anywhere from a few hours to two days. After cooking, your meat will be noticeably juicier. This transformation isn’t just your turkey absorbing fluid like an enormous meat sponge, but is instead an intricate interplay of diffusion, osmosis, and protein biochemistry.

Meat proteins typically respond to heat by unraveling like balls of yarn. Once unraveled, they tangle with each other and coagulate, causing the meat proteins to pack together more densely. This process forces water out, and coupled with the heat-driven evaporation of water, explains why meat shrinks when cooked. But when submerged in brine, meat is at the mercy of the salt molecules. Salt molecules are small and mobile and can easily move through muscle proteins. As they diffuse through the turkey, they partially dissolve proteins and interact with the charges on them, preventing the proteins from packing as tightly together and altering the overall structure of the meat (1). The movement of salt also drives water into the meat proteins since water tends to move from a higher concentration (the brine) to a lower concentration (within the meat). The combination of less tightly packed proteins and the gradient driving water in ultimately boosts the water-holding capacity of your turkey.

As with any cooking method, brining has its pros and cons. While the meat it creates may be juicier, a common complaint is that it is unsurprisingly (and to some, unpalatably) salty. Brines typically start at around 3% salt by weight—comparable to ocean water at 3.5% salt by weight. The takeaway from all this: if you suffer from dry turkey mouth year after year, brining may be a viable option, but flavors in your turkey should otherwise be balanced and boosted.


References cited

  1. McGee, Harold. On food and cooking: the science and lore of the kitchen. New York: Scribner, 2004. Print

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.
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Understanding the Carbon Footprints of What We Eat

By Science & Food | November 8, 2016 12:26 pm

Eat local. Avoid red meat. Beef is bad. The media is full of messages about food. Navigating the world of food choices can be challenging and overwhelming. Here is where some knowledge of food, and bit of science, can help. With science, we can identify the number of calories in a food item. We can also easily understand the amount of protein or fat to help us choose to eat – or avoid – particular foods.

Need more vitamin C? Food labels can also help us identify vitamin contents. Want to know whether a product is clean label? Food labels have your answer! However, a lasting challenge we have as consumers is being able to identify and assess the environmental impact of foods that we eat. In comes the CO2 equivalent as a solution. CO2 equivalent, or CO2e, is a common unit of measurement that allows us to standardize greenhouse gas emissions. For example, is it worse for the environment to eat 118 apples or a quarter pounder burger?

To standardize measurements of greenhouse gas emissions, grams CO2 equivalent (or CO2e) is a common unit of measurement. CO2e is calculated by multiplying the global warming potential (GWP) of the greenhouse gas (GHG) emissions produced by each food component by the amount of GHG produced. For example, beef production generates carbon dioxide, methane, and nitrous oxide. Since each of these three greenhouse gases has a different potency for environmental effects, they each of have their own pre-calculated global warming potential, or GWP. Thus, the relative effects of each GHG can be determined by multiplying this GWP factor by the amount of each GHG produced (ex. GWP(methane) x GHG(methane) = grams CO2e for methane). Then the CO2e for each GHG can be added together to yield the total grams CO2e for a particular food component [1]. By converting units to CO2e, we can easily compare the approximate carbon footprint of different foods.

To illustrate the carbon footprint of a beef versus vegetarian food, see this infographic (Fig. 1) that we created together with Professor Jenny Jay and the UCLA Healthy Campus Initiative. It is remarkable to see how one beef burrito produces 896 grams of CO2 equivalent, which is just over ten times the amount of CO2 equivalent of a veggie burrito at 88 grams CO2e [2]. In fact, a quarter pounder burger has the same CO2 equivalent as 118 apples [3].

Livestock contributes a remarkable 14.5% to global GHG emissions [2], in addition to water pollution, destruction of land, and and species extinction. Beef production is particularly demanding, requiring on average 28 times more land, 11 times more water, and producing 5 times the GHGs than the average of any other type of protein such as pork or chicken [4]. What we take away from this information is ultimately our own personal choice. However, knowledge of how the foods we eat impact our environment can ultimately empower us to make informed decisions – allowing us to make a responsible and educated choice whether to dig into that burger or break out the veggie patty!


References Cited:

  1. Chamberlain, A. GHG emissions: demystifying carbon dioxide equivalent (CO2e). http://info.era-environmental.com/blog/bid/58087/GHG-Emissions-Demystifying-Carbon-Dioxide-Equivalent-CO2e
  2. Jay, J., Rowat, A., & Malan, H. (2016). What’s the ‘footprint’ of a burrito? http://healthy.ucla.edu/foodday/burrito
  3. Jay, J. (2016). Personal communication.
  4. Eshel, G., Shepon, A., Makov, T., & Milo, R. (2014). Land, irrigation water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States. PNAS, 11(33). Retrieved from http://www.pnas.org/content/111/33/11996.full

Winter Produce & Wheat Wars

By Science & Food | November 3, 2016 10:00 am


With the abundance of food in America, few people give a second thought to eating summer produce in the middle of winter. The majority of salad greens and tomatoes sold in winter are imported to colder states from warmer climates. With the help of greenhouses, however, it is entirely possible to have locally grown lettuce in the midst of a snowy December! Paul Lightfoot, founder and CEO of the company Brightfarms, explains the pros and cons of greenhouse farms. The availability of wheat, however, may not be as celebrated by some people. Mark Kelley investigates the movement that’s changing the way we eat.
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Science & Food brings you content on food and science including but not limited to: the scientific and culinary aspects of food that you eat; how knowledge of science and technology can be used to make better food; how science is integral to understanding the impact of food on our health and environment; as well as profiles of scientists and chefs that are advancing the frontiers of science and food.

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