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 . 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.
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 . 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) . “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.
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.
: Ann M. Bode and Zigang Dong. “The Two Faces of Capsaicin.” 15 April 2011.
: Ann M. Bode and Zigang Dong. “The Two Faces of Capsaicin.” 15 April 2011.
Guest post by Nessa Riazi
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.
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…”  Harold McGee describes how these chambers were constructed to replicate air pollution around the globe, drawing chemicals emitted from tailpipes, smokestacks, and feedlots . 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 . 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 .
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?
 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
 McGee, Harold. The Flavor of Smog. Lucky Peach Magazine. http://luckypeach.com/the-flavor-of-smog/
 Twilley, Nicola. Smog Meringues. Edible Geography: Thinking Through Food. http://www.ediblegeography.com/smog-meringues/ 30 May 2015.
“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 . 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.
Pectinase is a general term for an enzyme that breaks down pectin, or the polysaccharide contained in plant tissue . 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 . Using a recipe from Chef Steps, I proceeded with the following protocol:
Recipe for Citrus Suprême :
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)
Place Peeled citrus, water, and Pectinex in a bowl.
Refrigerate for about 2 days. Rinse segments in water.
Voila! Perfect citrus supreme.
To speed up the reaction you can heat up the solution to 104°F/40°C for 30 minutes . 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 . 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.
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 . 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.
About 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.
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.
About 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
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 . 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 . In fact, a quarter pounder burger has the same CO2 equivalent as 118 apples .
Livestock contributes a remarkable 14.5% to global GHG emissions , 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 . 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!
The Impact of What We Eat: From Science & Technology to Eating Local
March 8, 2016
As part of our 2016 public lecture series, we explored the environmental and social impacts of food with a focus on science and technology. A major theme of this panel was how we can initiate change through consciously making food choices. For this discussion our panelists included Chef Daniel Patterson, Dr. Paul B. Thompson, and Dr. Kent Kirshenbaum. Chef Daniel Patterson shared how his restaurant LocoL strives to enhance and empower local communities. Dr. Paul B Thompson of Michigan State University discussed the ethical and philosophical implication of agricultural practices and food infrastructure on food producers. Dr. Kent Kirshenbaum of NYU Chemistry explored the latest scientific advances in food technology.
Check out the highlights or watch the full lecture below
Chef Daniel Patterson on how Locol acts as both a business and a charity
Chef Patterson discusses how his restaurant is “a profitable business that’s also compassionate” by bringing healthy and delicious food to an underserved community, while also encouraging economic development in the area.
Dr. Paul Thompson on balancing local and regional food production
Dr. Thompson explains that foods like fruits and vegetables can produced locally, while basic grains are best produced regionally in places best suited for their growth.
Dr. Kent Kirshenbaum on scientific advances in food that reduce our environmental impact
Dr. Kirshenbaum talks about plant-based meat substitutes as well as isolating components from environmentally sensitive ingredients to create more sustainable foods.
Dr. Paul Thompson talks about how farming practices are important for food safety
Dr. Thompson discusses the natural dangers of foods and shares how potato farmers use careful breeding to reduce the naturally occurring toxicity of the potato plant.
Dr. Kent Kirshenbaum explains how traditional cooking practices don’t ensure healthy food
Dr. Kirshenbaum explains how all food technology needs to be evaluated for safety and how even traditional practices like cooking over an open flame can cause a risk to health.
Chef Daniel Patterson explores deliciousness and the need for collaboration
Chef Patterson talks about how subjective taste and deliciousness can be and the importance collaboration between scientists and chefs for new food technology. Here, Chef Patterson recalls his experiences with new plant-based meats.
See the Entire Lecture Here
Guest post by Panisa Sundravorakul
Instant noodles are delicious, cheap, and easy to prepare. This combination of traits make instant noodles a seemingly perfect solution for college students’ hectic schedules and depleted bank accounts. Let us take a moment to appreciate what made instant noodles possible — let us savor the science behind this culinary delicacy.
Instant noodles are truly a technological marvel – they can last for up to 12 months on the shelf, and a tiny little packet of seasoning makes the noodles taste so good. You can thank science for making this all possible. The shelf life of instant noodles ranges from 4 to 12 months, depending on environmental factors. Finding ingredients that are stable for this long, especially fats and oils that are prone to oxidation, is a culinary challenge.
Antioxidants like tertiary-butyl hydroquinone (TBHQ) can extend the shelf life of instant noodles by preventing the oxidation of fats and oils; this happens by donating electrons to neutralize free radicals, which stabilize the radical’s instability . The texture of instant noodles is preserved by propylene glycol, which is found in the noodles mixture, and helps them retain moisture and prevent them from drying .
Monosodium L-glutamate (MSG) is a common additive used to enhance the flavor of instant noodles. This molecule adds a robust and savory flavor to food, which is commonly described as umami, the fifth flavor after salt, sweet, sour, and bitter. Recent studies have found L-glutamate (Glu) receptors and transduction molecules in the gut mucosa, as well as the oral cavity (REF). The gastric infusion of MSG activates several brain areas, such as the insular cortex that is linked to the regulation of homeostasis; the limbic system is linked to olfaction; and hypothalamus is linked to certain metabolic processes and hunger control. This suggests that Glu signaling via the gustatory and visceral pathway plays a crucial role in digestion, absorption, and metabolism. 
While noodles might be tasty, convenient, and save you money and time, they do not contain sufficient nutrients that fulfill the body’s daily nutritional needs. Instant noodles are relatively high in sodium, carbohydrates and fat, and quite low in protein, fiber, vitamins, and minerals . Figure 1 compares the daily nutrition intake as recommended by The National Institute of Health to the nutritional content in one package of instant noodles (Figure 1) . Instant noodles account for too much of daily sodium intake, and not enough for fiber, vitamin A and C, calcium, and iron daily intake.
There is no doubt that instant noodles are a fascinating food science innovation. Health-wise, instant noodles are certainly safe to eat, but if you are thinking about consuming them regularly, think again about how your health could benefit from eating more nutrient-rich foods.
The 2017 UCLA Science & Food public lecture series is here!
World-renowned chef Massimo Bottura, UCLA professor Jenny Jay, Zero Waste Consultant and “Waste Warrior” Amy Hammes will participate in a panel discussion moderated by Evan Kleiman on “Food waste: solutions informed by science,” hosted by Dr. Amy Rowat, Science and Food, and the UCLA Healthy Campus Initiative. The discussion will focus on measuring the environmental effects of food waste, how policy influences food waste and its relationship to hunger and the environment.
General admission tickets are available for $25 from the UCLA Central Ticket Office (CTO) . Tickets can be purchased from the UCLA CTO over the phone or in person and will not include additional fees or surcharges. The UCLA CTO is located on-campus and is open Monday–Friday, 10am –4pm. A UCLA CTO representative can be reached during these hours at 310-825-2101. Tickets can also be purchased online from Ticketmaster for $25 plus additional fees. A limited number of $5 student tickets are available to current UCLA students. These must be purchased in person at the UCLA CTO with a valid Bruin Card.
For questions, please email firstname.lastname@example.org.
Interacting with food is an incredibly sensual experience. One might imagine the smell of an oven roast, or picture an oozing chocolate lava cake, maybe even hear the crunch of a stale baguette. But what happens when you lose your sense of smell and taste?
Anosmia is a disorder where one loses their ability to smell. There are various forms of this unfortunate disorder: Congenital anosmia is when someone is unable to smell at birth, and hyposmia describes the diminishing sense of smell that develops over time. Our senses of smell and taste are interdependent, so if you lose one of these senses, you lose the other one too.
In understanding anosmia, it is critical to first grasp the science of smell. Whenever we breathe air, particles pass through our nose and bind to the olfactory receptors beneath the cribriform plate. The “nerve cells come into direct contact with the air we breathe,”  connecting the nose with the brain through the cribriform plate, a structure that resembles a honeycomb. This cribriform plate is crucial to our sense of smell, and any harm done to the plate can in turn damage the neurons that pass through it . Some of the individuals who develop anosmia or hyposmia are either subject to injuries of the head, nasal polyps, inhaling toxic chemicals, or an upper respiratory infection (URI)–such as a cold– that damaged the receptor neurons. Swelling of the nasal tissue as a result of inflammation may “stretch the receptor cells and damage their ability to function properly” . This is one potential factor, but further research is being conducted to understand more about the causes of anosmia.
As expressed by Nisha Pradhan, a college student who developed anosmia, her inability to smell is perhaps even affecting her memory, as she cannot recall certain scents from her past . While memories engage with all senses, though primarily with sight, we underestimate the role that smell has in providing a context for us to categorize our everyday life experiences; most importantly though its relevance personal health. Not being able to smell freshly baked cookies is unfortunate, but the inability to detect rotting milk or smoke from a nearby fire is dangerous. While in some cases anosmia can worsen, it is not always a permanent condition and can subside with time as nasal congestion or other issues subside. Scientists are currently conducting research to develop potential treatments for anosmia. The Monell Center—which focuses specifically on research relating to taste and smell– is testing to see if olfactory stem cells can be used to synthesize new olfactory neurons. Olfactory receptor cells have the ability “to regenerate from specialized stem cells across a persons lifetime.” These stem cells would be derived from healthy individuals and then be transplanted into the patient .
Though it may slip the crevices of one’s mind, the nose is a vulnerable organ essential in constructing our everyday perceptions of life around us. It allows us to retrace memories, map the physical world around us, and most importantly preserve well-being. Heightening our gastronomic experiences, our ability to smell and taste food is a gateway to more meaningful sensory, social phenomena and life without them could only become incredibly bland.
The Duncan grapefruit has been described as “the finest, sweetest grapefruit” in the world, but after 187 years as the reigning champion of the American breakfast, the grapefruit inexplicably disappeared from grocery shelves. After only a few decades, it seems like the Duncan is making a comeback in Maitland, Florida.
Meanwhile, a conflict over the essences of sweeteners like Equal and Splenda brings chemistry into the courtrooms.
Guest post by Earlene Mulyawan
Winter season is when comfort food seems to take priority over fresh produce. But eating local during winter season is easy! There are plenty of produce that are rich in nutrients and flavor during this time of the year. Winter produce can also be just as tasty and nutritious with some creativity and a little twist. Read on to learn about how these three winter vegetables.
Beets are round, little balls of vegetables that grow underground. They taste a little like dirt too, but in a unique sweet and earthy way. What gives these rooty vegetables their earthy flavor and aroma is an organic compound called geosmin, which is produced by microbes in the soil. It is also the main contributor to the strong scent that occurs when rain falls after a dry weather.
Beets are an excellent source of betaine, a nutrient that has potential to help fight inflammation, improve vascular risk factors and enhance performance . As a group, the anti-inflammatory molecules found in beets may provide cardiovascular benefits as indicated by large-scale studies, as well as anti-inflammatory benefits for other body systems . There are many ways you can enjoy eating beets: Eat them raw, roasted, as a salad topping, or pickled!
Brussels sprouts, along with kale, cabbage, and broccoli, are members of the cruciferous family of vegetables. However, many scientists favor the term “brassica vegetables” over “cruciferous vegetables.” Brassica vegetables are unique because they are rich in sulfur-containing compounds called glucosinolates.
Our body converts glucosinolates to indoles and isothiocyanates. Epidemiological studies indicate that human exposure to isothiocyanates and indoles through cruciferous vegetable consumption may decrease cancer risk, but the protective effects may be influenced by individual genetic variation in the metabolism and elimination of isothiocyonates from the body . Furthermore, a cohort study shows the inverse associations between the consumption of brassica vegetables and risk of lung cancer, stomach cancer, and all cancers taken together.
Of the case-control studies, 64% showed an inverse association between consumption of one or more brassica vegetables and risk of cancer at various sites . One cup of brussels sprouts contains only 38 calories, and provides us with more than the daily-recommended intake of Vitamins C and K, 125% and 243% respectively. There’s no doubt that brussels sprouts offer plenty of health benefits. A simple way to prepare brussels sprouts is to simply toss them in olive oil and salt, roast them in the oven. When properly cooked, they should be bright green with a slightly crispy texture, and delicious!
The health benefits of bright and cheery citrus fruits can help make your day a little brighter, as well. Citrus fruits are rich in Vitamin C and flavonoids. Flavonoids are a class of polyphenols found in various fruits and vegetables. There are over 5,000 different flavonoids. Naringin and hesperidin are flavonoids unique to citrus fruits. Naringin and its aglycone naringenin belong to this series of flavonoids and were found to display strong anti-inflammatory and antioxidant activities. Some studies even suggest that naringin supplementation is beneficial for the treatment of obesity, diabetes, hypertension, and metabolic syndrome .
Hesperidin facilitates the formation of vitamin C complex, which supports healthy immune system functions. It is useful, along with naringin, as a potential treatment for preventing the progression of hypoglycemia . These refreshing citrus fruits may just turn your frown upside down!
: Craig, Stuart AS. “Betaine in human nutrition1,2.” The American Journal of Clinical Nutrition. N.p., 01 Sept. 2004. Web. 07 Mar. 2017.
: Mercola, Dr. “Six Amazing Health Benefits of Eating Beets.” Mercola.com. N.p., 25 Jan. 2014. Web. 01 Mar. 2017.
: Higdon, Jane V., Barbara Delage, David E. Williams, and Roderick H. Dashwood. “Cruciferous Vegetables and Human Cancer Risk: Epidemiologic Evidence and Mechanistic Basis.” Pharmacological research: the official journal of the Italian Pharmacological Society. U.S. National Library of Medicine, Mar. 2007. Web. 01 Mar. 2017.
: G van Poppel, and D T Verhoeven , H Verhagen , R A Goldbohm. “Brassica Vegetables and Cancer Prevention. Epidemiology and Mechanisms – Journals – NCBI.” National Center for Biotechnology Information. U.S. National Library of Medicine, 1999. Web. 01 Mar. 2017.
: Alam, M. Ashraful, Nusrat Subhan, M. Mahbubur Rahman, Shaikh J. Uddin, and And Hasan M. Reza. “M. Ashraful Alam.” Advances in Nutrition: An International Review Journal. N.p., 01 July 2014. Web. 01 Mar. 2017.
: John, Aubri. “What Is Hesperidin (Vitamin P)?” LIVESTRONG.COM. Leaf Group, 16 Aug. 2013. Web. 07 Mar. 2017.
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.
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 .
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 . 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 . Increased awareness of the environmental burdens of the meat industry have further contributed to this move towards more seafood proteins . 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 .
The types of substitution vary, often substituting cheaper fish such as tilapia for more expensive fish such as grouper, cod, and snapper . 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 .
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 . 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 .
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 , 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,”  because they have flexibility in several base positions , DNA polymerase is used to extend the primers and replicate the DNA, effectively amplifying the amount of COI gene present in the sample .
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 . 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 .
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 .
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 . 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 .
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 . 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 . 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.
About 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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