Tag Archive for: flavor

Watermelon

/in /by
(Steve Evans/Flickr)

(Steve Evans/Flickr)

Nothing says “summer” quite like a big, juicy slice of watermelon. Even if you prefer it charred on the grill or blended into an icy agua fresca, watermelon is one of the best ways to beat the late-summer heat.

So what gives watermelon its refreshingly delicate flavor?

Turns out the answer is pretty complicated. Over the last few decades, scientists have identified dozens of flavor and aroma molecules that contribute to watermelon’s unique taste [1].

And here’s an interesting twist: a watermelon’s flavor has a lot to do with its color. Chow down on a yellow ‘Early Moonbeam,’ a pale ‘Cream of Saskatchewan,’ or a deep red ‘Crimson Sweet’ and you’ll likely notice different flavor profiles for each melon.

These watermelons don’t just look different, they taste different, too! (David MacTavish/Hutchinson Farm)

These watermelons don’t just look different, they taste different, too! (David MacTavish/Hutchinson Farm)

Several of watermelon’s flavor molecules form when colorful chemicals called carotenoids break down into smaller chemical compounds [2,3].

For example, the classic color of red watermelons comes from lycopene, the same molecule responsible for the color of red tomatoes. When lycopene breaks down, it forms key flavor compounds such as lemon-scented citral.

Orange melons don’t have much lycopene, but they make up for it with extra beta-carotene. This chemical – the same one that makes carrots orange – leads to a completely different set of flavor molecules, including floral beta-ionone.

Colorful molecules called carotenoids break down into different flavor compounds. Figure adapted from [2].

The chemistry of watermelon flavor is clearly complex, but scientists are still searching for individual molecules that mimic watermelon’s characteristic taste.

Most recently, a study identified a single molecule – dubbed “watermelon aldehyde” – that has a very distinct watermelon aroma [4]. Unfortunately (or fortunately, depending on your perspective), the molecule is too unstable to be used as a food additive. So for now, artificially flavored “watermelon” products will just have to keep on tasting nothing like watermelon.

Good thing there’s plenty of real, chemically complex watermelon to go around.

References

  1. Yajima I, Sakakibara H, Ide J, Yanai T, Hayashi K (1985) Volatile flavor components of watermelon (Citrullus vulgaris). Agric Biol Chem 49: 3145–3150. doi:10.1271/bbb1961.49.3145.
  2. Lewinsohn E, Sitrit Y, Bar E, Azulay Y, Meir A, et al. (2005) Carotenoid Pigmentation Affects the Volatile Composition of Tomato and Watermelon Fruits, As Revealed by Comparative Genetic Analyses. J Agric Food Chem 53: 3142–3148. doi:10.1021/jf047927t.
  3. Lewinsohn E, Sitrit Y, Bar E, Azulay Y, Ibdah M, et al. (2005) Not just colors—carotenoid degradation as a link between pigmentation and aroma in tomato and watermelon fruit. Trends Food Sci Technol 16: 407–415. doi:10.1016/j.tifs.2005.04.004.
  4. Genthner ER (2010) Identification of key odorants in fresh-cut watermelon aroma and structure-odor relationships of cis, cis-3, 6-nonadienal and ester analogs with cis, cis-3, 6-nonadiene, cis-3-nonene and cis-6-nonene backbone structures University of Illinois at Urbana-Champaign. Available: http://hdl.handle.net/2142/16898.

Liz Roth-JohnsonAbout the author: Liz Roth-Johnson received her Ph.D. in Molecular Biology at UCLA. If she’s not in the lab, you can usually find her experimenting in the kitchen.

Read more by Liz Roth-Johnson

Scrumptious Strawberries & Caffeine Jitters

/in /by

bananacoffee2cc_wide-f682009e4fcb4e6cdc8e51d18011dd58016d0183-s40-c85

Supermarket strawberries have become bland through decades of agriculture, so now scientists are figuring out how to bring its flavor back. In the meantime, that banana isn’t going to help with your caffeine jitters.
Read more

Flavor without the Calories: Scientists Create a Digital Taste Simulator

/in , /by

Think of any task and chances are someone is developing a new mobile electronic device for it. Technologies exist that pay for your coffee, track your UV light exposure, and even drive your car, but can one also simulate flavor? With that question in mind, scientists led by Nimesha Ranasinghe at the National University of Singapore are developing a device that can scintillate your tongue with sour, bitter, salty, and sweet tastes without the use of any chemicals or actual food.

The “Tongue Mounted Digital Taste Interface” uses a two-probe system to send electrical and thermal signals to the tongue to produce taste. By altering the magnitude of the electric currentA (20 – 200 mA), frequency of electric pulsesB (50-1000 Hz), and temperature (20 – 35 °C [68 – 95°F] ), the interface changes the flavor profile and intensity the wearer experiences. For example, increasing the magnitude of the electrical current strengthens sour, bitter, and salty sensations1.

Tongue_interface

Figure 1: Schematic of the Tongue Interface1

device_tongue

Figure 2: Interface applied to tongue1

To understand how this system works, you have to first understand the anatomy of a taste bud (Figure 3).

Taste_bud

Figure 3: Diagram of a Taste Bud2.

When food enters the mouth, it is broken by chewing and mixed with saliva, which dissolves small food molecules like salts and sugars. These small molecules enter the taste pore and react with taste receptor cells. These taste receptor cells activate attached nerves, which transfer electrical signals to the brain that transmit the sensation of taste. In other words, a molecular signal is converted into an electrical one. Direct stimulation of taste receptors with electricity bypasses the need for initiating the signal using molecules and directly triggers signals to the attached nerves cells, which produce taste. This is supported by research that shows electric stimulation of the tongue alone has produced sour, bitter, and salty sensations2.

In addition to an electrode, a temperature probe was also included, as changing temperatures can trigger taste sensations. For example, a previous study found that warming the front of the tongue evoked a sweet sensation, while cooling caused a salty/sour taste3. These scientists suggested this property of taste might be part of the hard wiring of the taste bud because the reverse had been shown to occur. Temperature specific nerve cells in the mouth were shown to respond to bitter and sour substances. Therefore, if temperature receptors can respond to taste, then taste receptors may also react to temperature.

While this technology is still in its infancy, it has the potential to enhance the overall gastronomic experience. Movies, video games, and TV shows could have flavor simulators that immerse your sense of taste into their world. Alternatively, chefs might be able to share the flavors of their dish remotely with patrons in the comfort of their own homes. Whatever its ultimate use, Nimesha Ranasinghe and his team’s work challenges our expectations of how flavor can be experienced and encourages others to push the boundaries of how new technologies interact with food.

Learn more about Digital Taste Interface

http://www.nimesha.info/digitaltaste.html#dti

 

References Cited

  1. Ranasinghe, N. et al. 2012. Tongue mounted interface for digitally actuating the sense of taste. 2012 16th Annual International Symposium on Wearable Computers (ISWC): 80-87
  2. Chandrashekar, J. et al. 2006. The receptors and cells for mammalian taste. Nature 444 (7117): 288-294
  3. Plattig, K. and Innitzer, J. 1976. Taste qualities elicited by electric stimulation of single human tongue papillae. Pflugers Archive European Journal of Physiology 361(2):115–120
  4. Cruz, A. and Green, B. 2000. Thermal stimulation of taste. Nature 403 (6772): 889-892.

Footnotes

  • A altering the magnitude of the electric current: The electric current, a measure of the flow of electric charges across a surface, is measured in amperes. A portable hearing aid is powered by about 0.7 microamperes, which is 3.5 times higher than the upper range of the taste electrode.
  • B frequency the electric pulses: The frequency of electric pulses is measured in hertz, which is defined as cycles per second. It is standard for the electricity (AC current) that you receive from an outlet in the US to operate at 60 Hz.

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

Cardamom

/in /by
Green & Black Cardamom

Photo Credit: Robin (FotoosVanRobin/Flickr)

Cardamom is the third most expensive spice by weight, behind only saffron and vanilla. But with a captivatingly complex flavor profile crammed into such a small package, there’s little mystery behind its steep price. This spice delivers a pungent taste that’s smokey, yet contains hints of coolness reminiscent of mint and lemon, packed inside the tiny black seeds of the small cardamom seed pod. The cardamom genera belong in the ginger family, Zingiberaceae. True cardamom, also known as green cardamom, falls within the genus Elettaria and is grown in India and Malaysia. Black cardamom is of the genus Amomum and grown primarily in Asia and Australia.

While popular in foods and drinks, cardamom is equally admired in traditional medicine. Therapeutic uses range from antiseptic, expectorant, stimulant, and tonic [1]. Cardamom oil is especially known to help alleviate digestive system problems, working as a laxative, colic, stomachic, and diuretic [1]. Perhaps most interesting is its airway relaxant potential in the treatment of asthma [2]. Cardamom contains flavenoids, which exhibit bronchodilatory activity, essential to asthma relief by relaxing constricted bronchial tubes [2]. Moreover, cardamom extracts were observed to relax carbachol- and potassium-induced contractions in tracheal tissues [2], effectively relieving bronchospasms in asthma attacks. Bronchospasms occur in instances of high levels of carbachol or potassium, which are able to cause tracheal tissue contractions by simultaneously opening L-type calcium channels and stimulating muscarinic receptors. Both calcium channels and muscarinic receptors regulate signals for smooth muscle thickening; carbachol and potassium interaction with these signaling pathways leads to airway constrictions. In the study, cardamom showed inhibitory effects against carbachol and potassium, enabling relaxation of the contracted tissues.

Whether the ailment is asthma, digestive problems, or simply thirst, cardamom is all the more reason to enjoy a spicy cup of masala chai.

References cited

  1. “Cardamom Essential Oil (a.k.a. Cardomon Essential Oil) Information.”Cardamom Oil (Elettaria Cardamomum). N.p., 29 May 2014.
  2. Khan A, Khan Q, Gilani A. Pharmacological Basis for the Medicinal Use of Cardamom in Asthma. Bangladesh Journal of Pharmacology. June 2011;6(1):34-37.

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.

Read more by Alice Phung

Cinnamon

/in /by
Cinnamon

Photo credit: Hans Braxmeier (Hans/Pixabay)

Sweet and spicy, cinnamon is one of the oldest spices known to humans; it is also a favorite topping or secret ingredient in both sweet and savory recipes. This warm spice is obtained from the dried inner bark of several species of trees within the Cinnamomum genus. True cinnamon however, sometimes known as Ceylon cinnamon, comes from C. verum (also, C. zeylanicum, the antiquated botanical name for the species), indigenous to Sri Lanka. Other Cinnamomum species that are cultivated for commercial purposes are C. burmannii (Indonesian cinnamon), C. loureiroi (Saigon cinnamon or Vietnamese cinnamon), and C. cassia (Cassia or Chinese cinnamon) [1].

Analysis of the fragrant essential oil from cinnamon bark reveals the main compound responsible for the sharp taste and scent of cinnamon comes from cinnamaldehyde (also known as cinnamic aldehyde). Since its identification in 1834 by French scientists, Jean-Baptiste Dumas and Eugene Péligot, cinnamaldehyde has been found to be a rather useful molecule outside of the spice rack. Studies have suggested that cinnamaldehyde has antioxidant properties, which makes it a promising anticancer agent [2]. Further, cinnamaldehyde has been shown to work effectively as pesticide, fungicide, and antimicrobial agent [3].

Of course, one of the most useful properties of cinnamaldehyde is making apple pies extra delicious.

Cinnamaldehyde-04

References cited

  1. Culinary Herbs and Spices. The Seasoning and Spice Association.
  2. Nagle A, Fei-Fei G, Jones G, Choon-Leng S, Wells G, Eng-Hui C. Induction of Tumor Cell Death through Targeting Tubulin and Evoking Dysregulation of Cell Cycle Regulatory Proteins by Multifunctional Cinnamaldehydes. Plos ONE. Nov 2012;7(11):1-13.
  3. Shan B, Cai YZ, Brooks JD, Corke H. Antibacterial Properties and Major Bioactive Components of Cinnamon Stick (Cinnamomum burmannii): Activity against Foodborne Pathogenic Bacteria. Journal of Agricultural Food Chemistry. 2007;55(14): 5484-90

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.

Read more by Alice Phung

Taste Tripping With Miracle Berries

/in /by
MiracleBerries

Miracle Berries (Wikimedia Commons)

Imagine eating a lemon and puckering to incredibly sour…no wait, incredibly sweet citrus syrup. Then you try some tart goat cheese, but to your surprise, it tastes like sugary frosting. An underripe pineapple? Better than candy. Salt and vinegar chips? Dessert!

This fantastical taste-changing sensation is the real-life effect of a West African fruit called Synsepalum dulcificum (Richardella Dulcifica), or the “miracle berry”, which physically alters taste receptors and causes sour foods to taste sweet.

How does this work?

The secret is a protein found in miracle berries called miraculin.

Miraculin

Miraculin Protein (Wikimedia Commons)

When a miracle berry is eaten, its molecules attach to the thousands of taste receptor cells located on taste buds lining the mouth, tongue, throat, and esophagus. Humans have at least five different kinds of taste receptors to detect five basic tastes: sweet, salty, sour, bitter, and umami. (Note that evidence in the last decade suggests that there may be additional taste receptors for lipids [1] – which may explain our natural affinity for fatty foods!) Miraculin, in particular, binds directly to the sweet-sensing taste receptor known as hT1R2-hT1R3.

The earliest scheme of miraculin-hT1R2-hT1R3 binding was based on a pH-dependent conformational change of the sweet receptor-protein complex. In this model, miraculin binds somewhere near the sweet receptor site (so there is no sweet taste at first), but at a lower pH (in sour or acidic environments), the receptor changes its shape so that miraculin can bind directly on the sweet receptor site and elicits a sweet taste [2]. That’s how miraculin causes a lemon, which creates a sour, acidic environment in your mouth, to taste so sweet!

MiraculinSour

More recent studies have found additional evidence that miraculin actually starts off directly attached to sweet receptor hT1R2-hT1R3 in neutral pH and activates it in the same place in an acidic environment. Experiments have shown that sweet receptors bound with miraculin are most responsive in acidic pH (4.8-6.5), but in general, the more sour environments lead to a greater intensity of sweet taste sensation [2]. In neutral pH (when miraculin is not activating the sweet receptors), miraculin actually has another effect: it blocks other sweeteners such as aspartame, sucrose, and saccharin, and other sweetness-inducing proteins like thaumatic and brazzein, from attaching to the hT1R2-hT1R3 receptor. Basically, miraculin claims the sweet receptor site for itself so that it can reactivate the site, allowing the magical sensations of sweetness to last for up to an hour.

MiraculinBlocksSweetReceptor

Even if miraculin can manipulate sweet taste receptors to make a lemon taste sweet, shouldn’t a lemon still taste sour? Little is currently known about whether or not miraculin actually inhibits sour taste receptors, but a neuroimaging study in 2006 has suggested that the electrical signals that transmit sour taste information diminish en route to the brain stem, and that only sweet taste signals even reach the brain for processing. In the study, participants were able to still detect both citric acid and sucrose after miraculin treatment, but the sweet taste dominated because 20% of the sourness may be suppressed at the receptor level, and most of it is suppressed in the central nervous system [3].

Miracle berries were historically used by West Africans to improve the taste of fermented bread and sour palm wine, but today’s applications may be life-changing. Miraculin is being studied as a therapy for chemotherapy patients suffering from dysgeusia, which is an unpleasant metallic taste distortion. In a 2012 pilot study, eight chemotherapy patients, who reported that most foods, including water, tasted metallic, bitter, or “spoiled”, were recruited to test the effects of miracle berries. After eating miracle berries for two weeks, patients showed substantial improvement in appetite, nutrition, and response to treatment because the miraculin either masked or eliminated the unpleasant tastes altogether [4]. In the meantime, expect to see an increased production of recombinant miraculin in transgenic fruits, booming commercial demand for miracle berries as low-calorie sweeteners, and some invites to trendy “taste tripping” miracle berry parties.

References

  1. Degrace-Passilly P, Besnard P (2012) CD36 and taste of fat. Curr Opin Clin Nutr Metab Care 15: 107–111.
  2. Koizumi A., et al. (2011) Human sweet taste receptor mediates acid-induced sweetness of miraculin. Proc. Natl. Acad. Sci. U.S.A. 108: 16819–16824.
  3. Yamamoto C, et al. (2006) Cortical representation of taste-modifying action of miracle fruit in humans. Neuroimage 33:1145-1151.
  4. Wilken M, Satiroff B (2012) Pilot study of “miracle fruit” to improve food palatability for patients receiving chemotherapy. Clinical Journal of Oncology Nursing 16:E173-E177.

Eunice LiuAbout the author: Eunice Liu is studying Neuroscience and Linguistics at UCLA. She attributes her love of food science to an obsession with watching bread rise in the oven.

Read more by Eunice Liu

Dana Small

/in /by

Dr. Dana Small is a Professor in Psychiatry at Yale University, a Fellow at the John B. Pierce Laboratory, and visiting Professor at the University of Cologne. Her research focuses on understanding the mechanisms behind flavor preference formation, investigating the role of cognition in chemosensory perception, and determining how the modern food environment impacts brain circuitry.  She currently serves on the executive committee for the Association for Chemoreception Sciences and the Society for the Study of Ingestive Behavior.

See Dana Small May 14, 2014 at “How We Taste”

dana_small

What hooked you on science? On food?
I just loved biology class. It was love at first sight. I became a neuroscientist interested in flavor and food because I wanted to understand neural circuits that regulate appetitive behavior. Neuroimaging had just become available and I wanted to know if what we understood about the neurobiology of appetitive behavior in rodents applied to humans. The rodent work was based on studies where rats pressed a lever to have food pellets dispensed. I guess that means that rat chow got me hooked on food!
The coolest example of science in food?
Jelly beans because they are the perfect food to demonstrate that “taste” is mostly smell.
The food you find most fascinating?
Soufflé.
What scientific concept–food related or otherwise–do you find most fascinating?
Evolution. I am interested in understanding how the environment shapes biology—including the food environment.

Are there any analogies you like to use to explain difficult or counterintuitive food science concepts?

If I can speak of neuroscience of flavor, then I like to compare the oral capture illusion (which occurs when volatiles that are in the nose are referred to the mouth) with the visual capture that occurs when one watches TV. The sounds comes from the speakers but appears to come from the actors’ mouths.
How does your scientific knowledge or training impact the way you cook?
My scientific knowledge totally influences how I cook and eat. I avoid all artificial sweeteners and liquid calories (OK, except wine). I rarely eat processed food. I buy organic and try to eat locally. I eat a big breakfast and a light dinner. I avoid foods high in glycemic index (except on a special occasion) and search out high fat yogurt as a favorite lunch.
One kitchen tool you could not live without?
In truth I should be kept out of the kitchen!
Four things most likely to be found in your fridge?
Raspberries, blueberries, strawberries, blackberries.
Your all-time favorite ingredient?
Eggplant.
Your standard breakfast?
Steel cut oats, pomegranate seeds, blueberries, raspberries, and sliced almonds. Its my biggest meal of the day. Double latte.

Texture and Color of Sashimi

/in /by

photo credits (sake puppets/flickr)

Whether or not you like eating sashimi, such a fine specimen of fish is undeniably an incredibly beautiful food. The subtle flavors, delicate texture and vivid colors make sushi and sashimi such a unique eating experience. To whet your appetite for The Science of Sushi at UCLA, here are some bits of sashimi science we learned from Ole G. Mouritsen’s book, Sushi: Food for the Eye, the Body, and the Soul.

Sashimi 刺身

5421609002_968a80d7c2_z

Salmon and Tuna Sashimi – Photo Credits: (avlxyz/flickr)

Why are fish muscles soft?

If you used your finger to poke a raw filet of a bony fish like salmon or tuna, then tried this on meat from a terrestrial animal like beef or pork, you would notice that fish muscle is significantly softer than terrestrial meat. On a very fresh piece of fish, you could poke your finger through the muscle. From a basic understanding of meat texture, it seems strange that the meat of a fast-swimming predator is soft while the flesh of a slow-moving grazer is firm; typically the more an animal uses its muscles, the tougher its muscles.

Yet fish tend to have the same density as the water in which they live, so they do not use their muscles to bear their own weight; fish need only to exert their muscles when they want to move. By contrast, terrestrial animals frequently use their muscles to counter gravity and remain upright. Fish simply have less work to do, and so their muscles do not develop the same chewy texture that land animals do. But not all fish have smooth and tender muscles; some species like shark have tougher meat. Why? Sharks’ bodies happen to have a specific gravity greater than the water they inhabit, so they must exert their muscles at all times to keep afloat, and thus their muscles more closely resemble a ruminant’s in firmness.

Fresh is best

About six hours after the fish is killed a phenomenon common to all animals, rigor mortis, sets in. During rigor mortis calcium ions of the proteins embedded in the muscle fibers are released, causing the muscle fibers to contract and become stiff.

To delay rigor mortis for up to a few days, fish can be deep-frozen immediately after they are caught. Once the process of rigor mortis has run its course, the fish begins to decompose, the muscle fibers separate, and the connective tissue loosens. At this point it is ideal to consume the fish, as it is at its peak of softness and freshness. This type of sushi is called nojime, the type made from fish that are not kept alive after being caught. The opposite is ikijime sushi, prepared from fish with firmer muscles as they are kept alive until the last moment and prepared before rigor mortis can set in.

A rainbow of fish

3883996818_21c5d30c2a_z

Orange, pink, red, white; there is remarkable variation in fish meat color. Photo Credit: Kake Pugh (kake/flickr)

Orange and pink

The muscles of wild salmon and sea trout are typically orange-pink in color. The origins of this distinct shade of salmon begins at the bottom of food chain, with plankton. These little organisms contain a pigment astaxanthin. It belongs to the family of pigments called carotenoids, which includes the pigment that makes carrots orange. Tiny crustaceans eat plankton, and thus ingest astaxanthin, whereupon it is bound to proteins called crustacyanins in the animals’ tough shell. While bound to these proteins, the pigment is blue-green or a dark red-brown. This will seem familiar if you have ever seen live crab or lobster. When a fish comes along and eats the crustacean, the crustacyanins are denatured and they release the pigment, allowing its own red-orange color to become visible. The color change that occurs upon cooking crustacean shells is caused by the same protein-denaturation and pigment-release process that occurs in fishes’ digestion systems.

Red Fish

Although the proteins that form the muscles themselves are colorless, a lot of fish meat is deep red, like tuna. These colored muscles are classified as slow muscles, as they take care of work that has to be carried out on an on-going basis, namely, continuous swimming. Since they require a continuous oxygen supply to produce energy, they contain myoglobin. Myoglobin is responsible for the transport of oxygen within muscle tissues. Each myoglobin molecule can bind one oxygen molecule to form oxy-myoglobin, which is bright red.

White fish

In contrast to slow muscles, fast muscles undertake smaller and more rapid movements like the slapping of fins and tail. These muscles do not contain myoglobin; instead they use the colorless starch glycogen to supply energy. No myoglobin means that these muscles stay colorless or white.

Interested in learning more sushi science from the experts? UCLA Science & Food’s public lecture, The Science of Sushi, is on April 23rd. In this lecture, Dr. Ole Mouritsen will illuminate the science underlying sashimi, nori, sushi rice, umami, and more.  He will be joined by Chef Morihiro Onodera who will share his approach to sushi as well as an inside look into his partnership with a rice farm in Uruguay.

References:

  1. Mouritsen, Ole G. Sushi: Food for the Eye, the Body & the Soul. New York: Springer, 2009. Print.

 

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

Wasabi

/in /by
Photo credit: Jun OHWADA (しそ山葵) (june29/Flickr)

Photo credit: Jun OHWADA (しそ山葵) (june29/Flickr)

Wasabi packs quite a punch, but where exactly does that wallop of heat come from? That green dollop that accompanies sushi comes from the wasabi plant, also known as Japanese horseradish, which is not to be confused with its distant cousin, the more common and well-known European horseradish (Armoracia rusticana). As a member of the Cruciferae family, wasabi is actually more closely related to cabbage, cauliflower, broccoli, and mustard [1][2].

Grown primarily in Japan, the wild-type species (Wasabia tenuis) are only found mountainside in streambeds and river sand bars [2]. Cultivated wasabi plants (W. japonica), similar to the wild-type variety, comprise a cluster of long-stemmed heart-shaped leaves and delicate, spring-blooming, white flowers branching from a gnarled, thick, root-like stem known as a rhizome [3]. Wasabi grown under semi-aquatic conditions are called sawa, while those grown in fields are called oka [1][3]. Sawa is considered higher quality, as they produce larger rhizomes, thereby often cultivated for culinary purposes. Oka is largely cultivated for nutraceutical purposes, such as herbal supplements [3].

Wasabi rhizomes. Photo Credit: Jaden (Steamy Kitchen)

Wasabi leaves and rhizomes. Photo credit: Jaden (Steamy Kitchen)

The plants are notoriously difficult to cultivate, as they thrive best in running water [4]. Even under ideal conditions, wasabi is difficult to farm, especially on large-scale operations for commercial purposes. As such, real wasabi is expensive and rare outside of Japan. Due to the taste similarities between wasabi and horseradish, common wasabi substitutes are usually a mixture of horseradish, mustard, starch, and green food coloring. So how does one differentiate between real and imitation wasabi? Simply taste it.

Real wasabi is made by grating the wasabi rhizome into a fine powder. Due to the high volatility of the flavor compounds, after grating the rhizome, the heat will only last for, at most, fifteen minutes, whereas horseradish-based wasabi can be left overnight and still retain its heat [1]. Additionally, though the chemical makeup of horseradish and wasabi may be similar, it is different enough that each has a unique flavor profile. Both horseradish and wasabi rhizomes contain thioglucosides, a sugar glucose with sulfur-containing organic compounds. Maceration of the rhizome, such as by grating, breaks the cell walls and releases these thioglucosides, as well as an enzyme known as myrosinase [1]. Myrosinase is responsible for breaking the thioglucosides into glucose and a complex mixture of a class of compounds called isothiocyanates. Horseradish and wasabi contain varying isothiocyanate amounts and compositions. There are 1.9g total isothiocyanates per kilogram of horseradish, as opposed to 2.1g/kg in wasabi. The most abundant and stable of these compounds, allyl isothiocyanate, gives real and imitation wasabi its infamous pungency [1][4]. The next most abundant isothiocyanate compound is 2-phenylethyl isothiocyanate, which is only found in horseradish [1]. All other types of isothiocyanates exist in higher concentrations in wasabi than horseradish.

AllylIsothiocyanate_Wasabi-03

Allyl isothiocyanate produces a hotness in wasabi that is distinct from the spiciness of hot peppers. Hot peppers contain capsaicin, an oil-based molecule which stimulates the tongue. This spiciness can only be washed away with foods containing oils or fats, such as dairy products. Unlike capsaicin, allyl isothiocyanate vapors stimulate the nasal passages. Fortunately for heat-seekers, the amount of pain is directly related to the amount of wasabi consumed, and a little will go a long way. Fortunately for mild-lovers, because allyl isothiocyanate is not oil-based, the burning can easily be cleansed by consuming more of any food or liquid. Although real wasabi is expensive and only found at specialty stores or prepared to order at high-end restaurants, that sinus-opening sharpness is worth experiencing, even if only once.

References Cited

  1. Arnaud, CH. What’s That Stuff? Wasabi. Chemical & Engineering News. March 2010; 88(12): 48.
  2. “Fresh Wasabi and Real Wasabi Paste – Technical Info.” Pacific Farms by Beaverton Foods. Beaverton Foods.
  3. “The Story of Wasabia Japonica.” Wasabia Japonica, Oka Wasabi, Semi-aquatic Sawa Wasabi. Pacific Coast Wasabi.
  4. “Wasabi (Wasabia Japonica (Miq.) Matsum.).” Gewürzseiten: Wasabi (Wasabia Japonica, Japanischer Meerrettich/Kren, わさび, 山葵).

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.

Read more by Alice Phung