Category Archives: Food

Yellow Thistle: My Prickly Preference

In spring, gardens and flowerbeds are transformed into immaculately manicured arrangements of botanicals in all colors, sizes and textures. I’d like to boast that my backyard could be described this way, but I’d be lying. Fortunately, spring also provides a spectacular array of wildflowers to make up for those of us disinclined to plant ordered ornamentals everywhere. I know. If that tendency weren’t bad enough to revoke my Master Gardener privileges, here’s a confession that surely will… One of my favorite spring ‘wildflowers’ that always appears in my backyard* is the Yellow Thistle.

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Justifying my affection for these prickly beasts is the subject of today’s blog post.

Its Latin name is Cirsium horridulum, and it does, frankly live up to its horrible name in appearance. I know the first sight of their spiky rosettes sends suburban homeowners running for the RoundUp, but there is something wickedly beautiful about these plants. At least, from a distance. On other people’s property, maybe.**

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Everything about them screams, “Stay away. Don’t touch!” But I am drawn in close to the fuzzy flowers. The new blooms are like velvet in shades of pink and purple, and then fade to yellow as they are pollinated. I am not the only one. Butterflies, bees, other insects, even some hummingbirds are attracted to these flowers for their nectar. The seeds are rich in oil and an important food source for seed-eating birds.

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Their sharp spines are clearly effective on soft-mouthed herbivores like most mammalian wildlife and pasture animals. Generally, humans stay away as well, but some know that the stalks are edible- tasty even. Don’t just start sautéing down the spiny leaves like spinach. It’s the stalks you’re after. If left alone and given enough nutrients, yellow thistles can grow to impressive heights (~6 ft), but choose shorter specimens for the most tender texture. They’ve been described as having a flavor akin to celery, but better. I, personally, have never tried them, but know it as a tradition of my grandparents’ childhood.*** Check out these links for more on edible thistles.

 

Thistles will probably never become incorporated into the landscaping plans of most suburban neighborhoods. But, now, when you see them in a roadside ditch or pastureland, maybe you can at least appreciate them for their functions  even if you can’t embrace the aesthetics of their form.

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This post was written for the May edition of the Berry Go Round plant blog carnival on Backyard Plants to Save the Planet hosted at the Roaming Naturalist blog.

 

Johnna

*Don’t think suburban backyard, think homestead with a lot of pastureland. Thistles are perfectly acceptable in my homestead’s HOA agreement.

**Bonus points to you, dear reader, if you may be of the same generation to now have a certain early 90’s rap song ear bug.

***I’ve never been adventurous enough or in a survival situation needing to rely on them. Although it’s good to know that I could. Or at least, that I have a head start on a crop of them on my property if they ever become popular in American cuisine. (Alternative science career possibility: thistle farmer. I should write that down.) Truth be known, wild blackberries are ripening at the same time of year as thistles are sprouting, and I’ll take blackberries over thistles anything any day of the week and twice on Sunday.

Photo credits: Johnna Roose, all rights reserved

References and Links:

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

https://www.wildflower.org/plants/result.php?id_plant=CIHO2

http://plants.usda.gov/core/profile?symbol=ciho2

http://hawthornhillwildflowers.blogspot.com/2012/05/purple-thistle-cirsium-horridulum.html

http://www.houstonaudubon.org/%28S%28cvmsgzeb5byelh55w05khx45%29%29/default.aspx?act=newsletter.aspx&newsletterid=1793&category=Natives&MenuGroup=NB&

http://southriverstories.com/2014/03/27/1158/

http://www.houmatoday.com/article/20100411/ARTICLES/100409375?p=1&tc=pg

http://plainoldkristi.blogspot.com/2009/03/eating-thistles.html

http://www.regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Cirshorr

 

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Heterotroph Denial

Alright readers, I have a lot to do today, but I feel compelled, nay, obligated to blog about something buzzing around the interwebz lately. Remarkably, no- this isn’t about plants or algae or any other autotroph. Confused since this is an all-autotroph blog? After reading a news article that Ukrainian model Valeria Lukyanova believes she can subsist on only air and sunlight, I have to set the record straight. Let me say this slowly so there is no confusion and please feel free to share this with your friends.

You. Are. Not. Photosynthetic.* Humans are heterotrophs. Full Stop.

It’s really important to me that you know this.

I hope that some of the links on my Basics page will explain why this ‘Breatharian’ lifestyle is crazy. Yes, sunlight is the main source of energy feeding into the Earth’s biosphere. This makes the sun both physically important to our survival and an intimate part of our human culture. The sun is critically important to the way we live because our lives depend on photosynthetic organisms. This is because truly photosynthetic organisms have biochemical machinery that can capture and convert the sun’s energy into useful energy storage molecules (ATP, NADPH, glucose). Even photosynthetic organisms require water for this process. Why do you think people get so up in arms about droughts?

Let’s consider the implications of a Breatharian reality.  If Breatharianism were possible, then why are there more than 800 million food-insecure people around the globe? Surely, they have access to sunlight. Should we just tell them to quit complaining and enjoy their sun? If this were the case, then agriculture is the biggest con of all time. So, let’s just not do it anymore. The food service industry is just profiteering off of the heterotrophic hoax as well. This conspiracy was all masterminded by some elite group of gardeners**, hunters and herders that swindled early humans into buying otherwise worthless crops, meat and dairy. Once the human population was hooked on the delicious calories, those robber barons have been laughing all the way to the bank. I’m quite sure that must’ve been how it all went down.

A brief on-line search reveals that Valeria is not the only adherent to this practice. Sigh. Sure, the human body is amazing and can endure periods of time without food and water, but our bodies cannot survive indefinitely without them. Check out the video below for a breakdown of what happens on a Breatharian lifestyle (aka dehydration and starvation).

I know I’ve mentioned KungFu Panda before, but this scene is worth mentioning today:

Tigress: It is said that the Dragon Warrior can survive for months on nothing but the dew of a single ginkgo leaf and the energy of the universe.

Po: I guess my body doesn’t know it’s the Dragon Warrior yet. I’m gonna need a lot more than dew and universe juice.

Yeah, Po. Me too.

Fasting is a common religious practice, but believing that one could solely subsist on sunlight and air as a lifestyle choice is just downright heterotroph denial. This post topic gets a special new category for blog posts here (head-desk). Respect what real photosynthetic organisms are doing for you today… and eat one of them. Then wash it down with the aqueous solution of your choice. I really hope we don’t have to cover this again.

Johnna

* Not even those sea slugs turned out to be photosynthetic. They looked like leaves crawling around the ocean floor. Srsly? What makes you think you will fare any better. Heterotroph = you have to eat something else.

** Yes, I seem to remember something about this in the Master Gardner handbook. Oops, I guess I let the cat out of the bag. Guess I won’t be getting my new card this year.

References and Links:

http://www.huffingtonpost.com/2014/02/28/breatharian-barbie-valeria-lukyanova_n_4873706.html

http://www.theguardian.com/world/2013/jun/14/living-on-light-without-food?guni=Article:in%20body%20link

http://science.howstuffworks.com/innovation/edible-innovations/breatharian.htm

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

http://www.thedailybeast.com/articles/2014/03/02/introducing-breatharianism-the-dumbest-diet-of-all-time.html

Botanical Mardi Gras Memorabilia

Happy Mardi Gras! There are a number of botanical components to the celebration of this holiday. Plants usually take a back seat to the glitzy synthetic pageantry of sequined costumes, feathered masks, plastic beads and cheap metal doubloons. Yet, Mardi Gras wouldn’t be the same without help from quite a few different plants. First and foremost, alcoholic beverages of all varieties are the results of the fermentation of any number of plant species from the sugarcane that makes the rum in your hurricane to the barley and rye in your whiskey. Quite a few plants contribute to our King Cake recipes too. However, there is another more direct use of plants in our Mardi Gras celebrations… coconuts. Those of you from Louisiana have probably already made the connection. Congratulations! For those of you that still have a New Orleans Mardi Gras celebration on your bucket lists, keep reading.

The hallmark throws of the Zulu parade are elaborately decorated coconuts. Yes, real coconuts. In an age where everything is mass-produced and made of some kind of petroleum-derived plastic product, at the heart of these prized souvenirs is an all-natural plant product. Members of the Zulu Social Aid and Pleasure Club (AKA The Krewe of Zulu) have a long tradition of decorating these ‘golden nuggets’ by hand to throw at revelers along the parade route. The coconuts are scraped of their hairy covering, drained of their milk, sanded smooth and decorated with colorful designs.

Cukoo for Zulu coconuts! by missbhavens via Flickr http://www.flickr.com/photos/missbekah/3306604339/

Cukoo for Zulu coconuts!
by missbhavens via Flickr
http://www.flickr.com/photos/missbekah/3306604339/

As you might imagine, throwing coconuts into a crowd of drunken partiers may not be the best idea in today’s litigious society. After all, they are quite hard and after drinking a hurricane or two (or three) one’s reflexes are not as quick as they should be to avoid taking a hit to the face. The Krewe of Zulu was almost unable to acquire the necessary insurance for their parade in 1987 because of their signature throw. Not to worry- the Louisiana government came to their rescue. A special law was enacted in 1988 (SB188) to “exclude the coconut from liability for alleged injuries arising from the coconuts handed from the floats.” Thus, these ‘throws’ are now handed directly to revelers along the parade route.

2005 Zulu coconut by Courtney "Coco" Mault via Flickr http://www.flickr.com/photos/contusion/5521341257/

2005 Zulu coconut by Courtney “Coco” Mault via Flickr http://www.flickr.com/photos/contusion/5521341257/

The majority of the 100,000 Zulu coconuts procured each year are ordered from Vietnam. Traditionally, Zulu Krewe members transform the coconut from its whole, intact state to glitter-bedazzled throw. However, more and more members are resorting to using pre-drained and smoothed coconuts from a factory. Nevertheless, the members of the Zulu Social Aid and Pleasure Club put in an enormous amount of work into preparing the coveted coconuts. The most common colors are silver and gold to represent wealth, but some are painted black, representing coal. Each is unique and as ostentatious as the Mardi Gras carnival itself.

Franz Eugen Köhler, Köhler’s Medizinal-Pflanzen via Wikipedia

Often, the Zulu coconuts have faces that take advantage of the pattern of natural circular indentations on one end of the coconut. These pores are more than just a convenient pattern for anthropomorphic decorations, but are a consequence of the coconut palm’s reproductive biology. The coconut palm (Cocos nucifera) produces an inflorescence with both male and female flowers. The female flowers contain three ovules (tricarpellary ovary; plant biology word of the day) which could be pollinated and develop into an embryo within the fruit. The embryo (yes, just a baby plant waiting within the seed) develops just behind the pores on the coconut. While every coconut has the potential to form three embryos within each female flower, usually only one matures and this is the functional pore of the three. The functional pore can be pierced through, while the coconut shell has hardened over the other pores. If you leave your coconut under the right conditions (provided it hasn’t been drained of its milk), the embryo will continue to develop within the coconut and eventually it will start to sprout through the functional pore.

Coconut palm (Cocos nucifera) germinating on Punaluu Black Sand Beach, island of Hawai’i. by Wmpearl via Wikipedia

Now you know more than you ever wanted to know about the importance of coconuts to one of our most beloved Louisiana traditions and the biology behind their ‘faces.’ If this has inspired you to see it for yourself, the Krewe of Zulu parade rolls bright and early Mardi Gras morning (this year: 03/04/14, 8am), so pace yourself at the Monday evening parades. Yell, “Throw me something, mister!” convincingly enough and you could get your own plant-based Mardi Gras memorabilia.

Johnna

References and Links:

http://www.nola.com/treme-hbo/index.ssf/2011/06/zulu_explained_the_club_the_co.html

http://www.kreweofzulu.com/history

http://www.coconut.com/features/zulucoco.html

http://www.wwltv.com/entertainment/mardi-gras/slideshows/What-goes-into-making-a-Zulu-coconut.html?gallery=y#/entertainment/mardi-gras/slideshows/What-goes-into-making-a-Zulu-coconut.html?gallery=y&img=10&c=y

http://www.coconutresearchcenter.org/

http://www.kew.org/plants/palms/coconut.html

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

http://waynesword.palomar.edu/ecoph10.htm

http://www.dipbot.unict.it/palms/descr01.html

http://waynesword.palomar.edu/ecoph8.htm

http://agritech.tnau.ac.in/horticulture/horti_plantation%20crops_coconut.html

Chocolate

“Life is like a box of chocolates. You never know what you’re gonna get.” Forrest Gump

akira yamada via Wikimedia commons

As you’re peering into your heart-shaped box of chocolates this Valentine’s Day, you may have questions. Which one will have the caramel? Which one has almonds? Coconut? How do I avoid that weird fruity ganache I hate? Well, trial and error is always a strategic possibility, but if you’d prefer fewer surprises those boxes usually have a key of some sort to tell you which flavor corresponds to which confection. It’s probably in that paper layer that you tossed aside as soon as you opened the box.

But these can’t be your only questions. I know you come here for the plant science. So let’s explore the tree behind the treats.

Theobroma cacao with fruit Credit: Luisovalles via Wikipedia

Chocolate is prepared from the seeds of the tree Theobroma cacao. This small, shade-loving tree is native to the rainforests of Central and South America. It prefers a tropical environment and is cultivated in areas located within 20 degrees of the equator. Flowers develop on the trunk of the tree and once pollinated, they develop into yellow-orange oblong fruits that look more like Nerf footballs than anything you might want to try to eat.* Each pod contains between 20 and 60 seeds. The seeds are high in fat and contain a variety of aromatic chemicals that provide the beloved flavor. Check out the videos below that take you from the tropical tree to the treats in your Valentine’s Day box.

Theobroma cacao flowers Credit: Kurt Stuber via Wikipedia

Now, I could stop writing this post at this point because I’m sure the majority of my readers have already learned more than they thought they possibly could about cocoa trees (unless of course you are a plant scientist or chocolatier). However, in my opinion, chocolate is all about over-the-top decadence. So prepare to overindulge in the next level of chocolate science.

Cross-section of cacao fruit Credit: Keith Weller, USDA ARS via Wikipedia

There are three main cultivars of Theobroma cacao used for chocolate production. The vast majority of commercial chocolate production (80 – 90%) uses ‘Forastero,’ which provides high yields and disease resistance. It’s not the highest quality, but can be produced in large quantities and blended with other varieties to improve flavor. The ‘Crillo’ variety produces the finest quality chocolate, but is the rarest comprising only 5-10% of world production because of low yields and less robust trees. The ‘Trinitero’ variety accounts for 10 – 15% of world production and is a hybrid of the other two varieties. Clearly, these different varieties will command different prices in the world chocolate trade. However, the seeds have indistinguishable appearances. Given the large number of small stakeholder farmers and the middlemen of the cocoa trade, it can be a problem for chocolate producers to know what they are getting (or how much they should pay for it). Researchers have recently developed a genetic test that can be performed on cocoa bean samples to establish their true identity and value. This type of testing has clear benefits to chocolate producers in terms of quality control and financial savings and it may be implemented as standard practice someday soon. Consumers, like Forrest Gump, may still be wondering about the contents of their holiday confections, but nanofluidic single nucleotide polymorphism (SNP) genotyping will ensure that chocolatiers know exactly what they’re getting.

Cacao Beans Credit: David Monniaux via Wikipedia

Hungry for more chocolate trivia?

Theobroma cacao may be native to Central America, but the Ivory Coast is the world’s leading cocoa producer yielding more than 1.6 million tons annually. West Africa dominates cocoa production for the world.

Valentine’s Day is a popular day for chocolate and the highest single day for chocolate sales is February 13th. We purchase around 60 million pounds of chocolate worth about $350 million in the days surrounding Valentine’s Day. This includes about 36 million heart-shaped boxes filled with chocolate candies. Impressive to be sure, but Easter and Halloween still trump V-Day for holiday sales of chocolate.

Each American eats about 10 – 12 pounds of chocolate every year. We may be accused of many excesses compared to the rest of the world, but we are not superlative at chocolate consumption. The world leader- the Swiss consume an average of 21 pounds of chocolate annually.

If you still need more Valentine’s Day plant science, check out yesterday’s post Roses are red or the V-Day edition of Plants in Pop Culture by Postdoc Street or Say it with flowers by Malcolm Campbell. If you’re more in the mood for scary and unsettling chocolate-related news, read Ed Yong’s Ant farm from Aeon magazine. OK, that’s enough reading. For crying out loud, go tell someone you love them (with plants).

Johnna

*Thankfully, the ancient Olmecs were gustatory adventurers and developed a way to enjoy the chocolate flavor. Needless to say, Columbus liked the drink and there was no keeping it a secret from Europe. Check out the links below for more on the fascinating history of chocolate.

References and Links:

http://www.thestoryofchocolate.com/

http://www.kew.org/plants-fungi/Theobroma-cacao.htm

http://www.icco.org/about-cocoa/growing-cocoa.html

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

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

http://www.xocoatl.org/variety.htm

http://news.sciencemag.org/biology/2014/01/scienceshot-genetic-test-high-quality-chocolate

http://www.delish.com/food/recalls-reviews/facts-about-chocolate

http://www.tinyprints.com/interesting-chocolate-statistics.htm

http://www.cnn.com/2013/02/13/living/valentines-day-statistics-btn/

http://www.statisticbrain.com/valentines-day-statistics/

http://candy.about.com/od/thecandyindustry/a/vday_trivia.htm

http://www.zchocolat.com/en/the_history_of_chocolate.asp

http://www.bostonhistory.org/sub/bakerschocolate/choc_industry.html

http://news.sciencemag.org/biology/2014/01/scienceshot-genetic-test-high-quality-chocolate

http://pubs.acs.org/doi/abs/10.1021/jf404402v

Hot Peppers under the Microscope

Something new under the sun… pepper pigment packaging.*

pepper

Just when you thought you had seen the last of red hot chile peppers in the Superbowl halftime show yesterday**, I’m still talking about Capsicum science. The other pepper-themed posts have been all about the heat, but capsaicin isn’t the only chemical these plants make. Capsicum species are also great at producing nutritious carotenoids. Again, because Capsicum species grow well in arid environments, they offer an advantageous platform for providing these nutrients in an efficient way. In order to get our peppers to pack more punch in the nutrition department, we must better understand the metabolic machinery that makes these colorful molecules.

Carotenoids are the pigments that give us the yellow, orange and red colors in our peppers. You may be familiar with the common beta carotene molecule that is the precursor for vitamin A. That’s just one pigment. Plants and peppers, in particular, are adept at making a wide range of colorful carotenoids. However, all peppers start out green because the cells of the fruit contain photosynthetically active chloroplasts. As the fruit matures, these green chloroplasts undergo a major developmental change to become colorful chromoplasts. This process involves changes in gene expression, protein function, membrane structure and overall metabolism. By the end of the transition, chromoplasts are filled with an array of carotenoids, giving the fruit its hallmark red color.

Today’s journal club features a recent paper by Kilcrease et al that explores pigment localization within the chromoplasts of living plant tissue. This combines the Capsicum expertise of New Mexico State and the hyperspectral imaging capabilities of the Timlin lab at Sandia National Labs.*** It turns out that the different pepper varieties make characteristic carotenoids and these are made/stored in specific intracellular sites.

Here’s how the science breaks down:

Observations: For this example, observations are coming from two different directions (pepper pigment biology and spectral imaging method development).

Different pepper varieties produce different arrays of carotenoid pigments in their mature fruit. The literature suggested that there were significant differences in chromoplast morphology among these varieties. Some experimental evidence suggested that certain pigments were so concentrated they formed crystals within the plant cells.

Hyperspectral confocal Raman microscopy**** can provide chemical information in high resolution on living plant tissue. The molecular structure of chemicals like carotenoids makes them straightforward to identify. Using multivariate image analysis, a spatial model can be generated to show where the chemicals are within the microscopic image.

Hypothesis: Hyperspectral confocal Raman microscopy can be used to determine the carotenoid localization within the ripe fruit of different pepper varieties. This data will show whether or not the pigments are localized in distinct places within chromoplasts.

Experiment: Researchers analyzed the tissue of 5 different hot pepper varieties (mature fruit; and no, they didn’t use Bhut Jolokias or Scorpion peppers) using four different microscopic techniques (scanning electron microscopy, transmission electron microscopy, laser scanning microscopy, and hyperspectral confocal Raman spectroscopy) to identify subcellular localization of carotenoid pigments. The pigment content of each of the peppers was also analyzed using the analytical chemistry technique HPLC.

Results: The different types of peppers analyzed in this study varied considerably in carotenoid composition, chromoplast structure and sublocalization of carotenoids. The pigments did localize to specific sites within the chromoplast as well as some subcellular lipid bodies outside of the chromoplast.

Conclusions: The combination of these methods allowed for the more complete characterization of chromoplast structure and pigment composition in five different pepper varieties. These data can serve as new traits when considering breeding peppers for increased nutrient content.

Think Ahead:  The example the authors give is for aiding in the breeding of superior chiles in terms of increased carotenoid content. For example, a variety with high carotenoid content can be crossed with one with large chromoplasts to potentially yield offspring with even more carotenoids filling the larger chromoplasts. In this way, the results from these analyses will provide new molecular traits characteristic of certain pepper varieties. Genetics can then be used to mix and match those traits in desirable ways. Also, all of these experiments were performed on fruit that was already at a certain stage of ripeness. It will be interesting to perform an extended analysis on fruit as it ripens from green to red. This kind of time course experiment will yield more information about how these specialized synthesis and storage sites for the different carotenoids form as the chromoplast develops.

Ultimately, knowing more about how peppers make their carotenoids will allow scientists and breeders to develop more nutritious plants. This means not only understanding the chemical synthesis of these molecules, but also how the plant cells physically/spatially accommodate the increase in those metabolic pathways.

Johnna

*Say that fast 3x!

**It was a weird pairing of performers, but ‘Give it away’ still rocks IMHO.

***The second author on this paper is Aaron Collins (Sandia National Labs), an old grad school and photosynthesizer colleague of mine from WashU. He mentioned this project to me at a meeting last summer and bragged about the benefits of collaborating with biologists working on Capsicum (=pepper perks!).

****Yes, as fancy as it sounds.

References and Links:

(Caution: paywall for full text) http://www.ncbi.nlm.nih.gov/pubmed/24118159

Here’s a nice research highlight with the Raman microscopy figure) http://parc.wustl.edu/files/parc/Timlin_PARC_EFRC_Research_Highlight_September_2013.pdf

For more on hyperspectral imaging: http://www.sandia.gov/bioenergy-biodefense/timlin.html

For more on chile peppers: http://www.chilepepperinstitute.org/

Hot or Not? Nature vs. Nurture for Hot Pepper Pungency

Across much of the U.S. temperatures are still freezing and there’s still snow on the ground with more to come in the near future. So, today’s post will again feature the spiciness of hot peppers to offer some heat. Of course, here in Louisiana, the high will be an air-conditioner-worthy 74F this afternoon, when just a couple of days before it was a civilization-crippling 28F! Well, southern winters are not the only thing that suffers from a high degree of variability when it comes to heat. Let’s talk about what makes some peppers hot and others not.

A display of hot peppers and a board explaining the Scoville scale at the H-E-B Central Market location in Houston, Texas via Wikipedia, Credit: WhispertoMe

As I mentioned in my previous post, different cultivars of hot peppers can have very different levels of spiciness. They can range from pleasantly mild banana peppers to you’ve-gotta-get-a-video-of-me-eating-this-no-wait-stop-filming-and-take-me-to-the-hospital Smokin’ Ed’s Carolina Reaper peppers. Why? Genetics has a lot to do with it. Pepper breeders and plant scientists have been identifying the genes responsible for spiciness (pungency). Pun1 (Pungency1) is the gene with the most effect on spiciness identified to date. Its gene product adds the tail portion onto vanillylamine, converting it to capsaicin.* Individuals or varieties with mutations in the Pun1 gene have drastically reduced capsaicin levels. I’m not sure that any work has yet been done on the Trinidad Moruga Scorpion or Carolina Reaper peppers, but it’s a safe bet they have a functional Pun1 gene. They may express it in greater amounts than other lesser peppers to explain their insanely high Scoville ratings. But that’s only one gene and pungency is a complex trait. In the super spicy varieties, I’m sure there are multiple factors at work channeling metabolism into a perfect firestorm of capsaicin synthesis. The genome sequence of Capsicum was published this year in Nature (open access!), and scientists hope to find even more clues to pepper pungency among other traits within it.

Genetics, however, is only part of the story. The environment has a significant impact on how spicy the harvested peppers will be. This includes everything from soil composition, fertilization, temperature, and water stress. It turns out that any kind of stress (high temperatures, drought) tends to increase pepper pungency. For hobby gardeners, this means you may want to stress your pepper plants if you’re interested in turning up the heat in your pepper jelly. Just make sure you stress them while the fruit is developing and ripening and do not try to kill the plants right from the beginning.

Variability due to environmental factors can be a problem for commercial pepper growers. For hot peppers that fall in the middle of the Scoville scale and make up the main ingredients of hot sauces and salsas, the environmental factors can swing the measured spiciness of peppers by more than the genetic factors. It may come as a surprise to you, but not everyone is on a quest to pump up the pungency of peppers. Some of us like mild or medium salsas. Growers are usually contracted with chile processors that have particular pungency preferences, and it is in the growers’ interests to meet those demands precisely.

This peck of a problem means that plant scientists have more work to do when it comes to determining how environmental factors affect the spiciness of certain varieties so they can offer recommendations for farmers. However, as with our weather this past week, we are all at the mercy of Nature and there are some conditions that cannot be controlled. This is where plant scientists fall back on the genetic component. By understanding the fundamentals of why the plants are responding to the environment, breeders can develop pepper plants that rely less on environmental factors and more on their genetics for their characteristic pungency.

Worldwide, the hot pepper market is worth ~$14 billion annually and it’s growing. I’m sure hot sauce, hot wings, salsa, chili powder and other pepper products are on your shopping lists this weekend for the Super Bowl, right? While you’re enjoying the game (and/or the commercials) and chowing down on these pepper products, take a moment to acknowledge the hard work that plant scientists, breeders and farmers are doing to make sure you have just the right amount of spice in your life.

Johnna

*Remember when I told you that Capsicum sp. could take you from plain vanilla to superfirehot capsaicin in just a couple of chemical steps? Well, Pun1 performs step 2.

References and Links:

http://www.ncbi.nlm.nih.gov/pubmed/15918882

http://www.nature.com/ng/journal/vaop/ncurrent/pdf/ng.2877.pdf

http://www.extension.org/pages/32603/pepper-heat#.Uu0p47SgS_s

http://www.mdpi.com/1420-3049/18/11/13471

http://www.chilepepperinstitute.org/content/files/environment_produces_significant_effect.pdf

http://hortsci.ashspublications.org/content/46/12/1576.full.pdf

http://hortsci.ashspublications.org/content/43/5/1549.full

http://www.chilepepperinstitute.org/content/files/eval_genotype_environment.pdf

http://www.chilepepperinstitute.org/content/files/pungency_of_chile%281%29.pdf

Hot Peppers

This January morning finds most of the United States in freezing temperatures. We’re covered in ice here in Louisiana. It sucks to be you Duluth, MN. I mean, they’re even putting jackets on in San Diego! Get it? It’s cold. So, today’s post is intended to warm you up. Let’s talk about heat, spiciness that is. In the plant world, that means red hot chile* peppers, Capsicum sp. not one of my favorite rock bands. Here’s more than you ever wanted to know about the plants behind the piquant and the chemistry behind the chile.

Cubanelle peppers via Wikipedia

Capsicum plants belong to the Solanaceae family along with tomatoes, potatoes, tobacco and petunias. There are five domesticated species C. annuum, C. baccatum, C. chinense, C. frutescens, and C. pubescens and about 22 wild species. From chili to hot sauce to salsa to creole seasonings, hot peppers are big business in the United States (>$400 million). The top chile producing states are New Mexico, California, Arizona and Texas. It’s not all about the heat though. The Chile Pepper Institute in New Mexico is dedicated to Capsicum research for better varieties- bigger, more flavor, more color, more heat, and more disease-resistance. Not only are they delicious, but the plants thrive in hot, arid climates and provide lots of nutritious beta carotene.

Scoville

The traditional measure of spicy heat when it comes to Capsicum flavor is the Scoville scale, which was developed in 1912 by pharmacist Wilbur Scoville. In this test, a hot pepper extract is serially diluted in water and a panel of tasters report whether they taste the heat. Scoville Heat Units (SHU) indicate the degree to which a pepper’s extract can be diluted and the hot taste is still detectable. Thus, the higher the SHU, the more spicy the pepper. Obviously, this subjective test depends on the sensitivity of the tasters. Modern tests still report spiciness as SHUs, but the detection is done using analytical chemistry techniques and not panels of tasters. We now know what chemicals in the peppers (more on that below) are responsible for their spiciness, and they can be accurately detected and quantified. These measurements can be converted over to the popularly familiar Scoville scale.

Who’s the hottest of them all?

Jalapenos, Serranos, and even Bird’s eye peppers can all just sit down (5,000 – 100,000 SHU). Even if you’re not a hot pepper aficionado, you may have heard of Habaneros or Scotch Bonnet peppers (100,000 – 700,000 SHU). Nope, not them either. Other hot pepper enthusiasts (or funny Youtube videowatchers) have probably heard of Bhut Jolokia (aka Ghost) peppers, which were the reigning champions of hottest peppers in the world several years ago, checking in at (1 million SHU). The hottest chile pepper tested by the Chile Pepper Institute is the Trinidad Moruga Scorpion pepper (1.8 – 2 million SHU).  The current world record holder for the hottest pepper is a variety called Smokin’ Ed’s Carolina Reaper (2 million SHU) developed by Ed Currie of PuckerButt Pepper Company in South Carolina. Really, I think the variety and company name says it all. Of course, the Simpson’s gave us the hottest fictional peppers (the merciless peppers of Quetzalacatenango).

Capsacinoids and Feeling the Heat

Capsaicin via Wikipedia

The chemical responsible all of this heat is capsaicin and other capsaicinoids. They are alkaloid compounds derived from simple phenolics like vanillin, but much more elaborate. Yes, plants can take you from plain vanilla to superfirehot capsaicin in just a few chemical transformations. I’ll spare you the details of organic synthesis, but the biology is interesting enough to dwell on a moment. Capsaicin binds to and triggers the Transient Receptor Potential cation channel subfamily V member 1 (we’re going to call that TRPV1 from now on). At temperatures greater than about 109 F (43 C), the TRPV1 channel opens and gives us a painful heat sensation, so that we can recognize the pain and avoid the cause of it. Capsaicin binds to this receptor and triggers it to open at lower temperatures, giving us a burning sensation without any real heat.** This property is medically useful and capsaicin can be found in low concentrations in creams to give a warming sensation to relieve muscle and arthritic pain. Humans can build up a resistance to capsaicin by long term exposure to the molecule, for example, by eating hot chile peppers over their lifetime. Tolerance never gets high enough to resist capsaicin spray to the face, which is the active ingredient in pepper sprays. Of course, there are molecules with higher Scoville ratings than even pure capsaicin, orders of magnitude higher. The chemicals resiniferatoxin and tinyatoxin are naturally-occurring chemicals made by the cactus-like spurge plants Euphorbia poissoni. If one were so inclined, you could create a GMO chile pepper that produced these compounds as well, but the resulting fruit would likely be lethal.

Why are they so hot?

Modern plant breeding by humans has escalated the amount of capsaicinoids in some varieties because humans value the novelty of spiciness, but these chemicals serve an important function for the plant. Pepper plants produce these secondary metabolites as a feeding deterrent for mammals. The concentration of capsaicinoids is highest in the white pith along the inner wall of the peppers. Because, you know, most mammalian species are smart enough to avoid eating these plants. Fun fact, outside of an agricultural setting, peppers rely on birds to disperse their seeds. Birds are impervious to the effects of capsaicin (yes, due to differences in TRPV1 receptors). The birds eat the peppers without damaging the seeds allowing them to poop the seeds out elsewhere and ensure propagation of the next generation of plants. It’s a great deal for the plants and also works out nicely for the birds. Mammals, on the other hand, have grinding molars that would crush the seeds when the peppers are eaten. This would be a significant disadvantage for the plants. Since the plants cannot run away from mammalian herbivores, they must resort to elaborate biochemistry for defense.

Growing hot peppers

Since January is the time many gardeners spend their time flipping through seed catalogs, earmarking pages and fantasizing about spring planting, you may want to spend your cold day today considering some of the hot varieties mentioned in this post. Seeds for peppers of many varieties are available from the Chile Pepper Institute, including the Bhut Jolokia and Trinidad Moruga Scorpion peppers. Also check out their section on pepper-growing tips. You can buy seeds for the Carolina Reaper peppers here. I know I’ll be purchasing some of these seeds; stay tuned for a follow up post later this summer to see how they turn out. I’m hoping to create some Youtube-worthy pepper jelly this year!

Johnna

*I’m using the terminology employed by The Chile Pepper Institute; chile = Capsicum plants and plant parts and chili = culinary dish comprised of peppers, meat, tomatoes and beans. (I realize that some people may be very anti-bean when it comes to the chili definition, but I am not taking a position on that at this time. You get the idea.)

**For those loyal readers that have been paying attention, this phenomenon is similar to the effects of menthol from peppermint extract, which gives a pleasurable cooling sensation by activating a different receptor in our nervous system. Hypothesis: The simultaneous ingestion of cooling menthol along with hot chile peppers may weaken the capsaicin effects. I’m going to put my money on the null hypothesis or that the effect will be amplified in an extremely uncomfortable way, but SuperChef has volunteered to be the subject in the experiment to test this hypothesis.

References and Links:

http://www.chilepepperinstitute.org/

http://www.chm.bris.ac.uk/motm/chilli/index.htm

http://antoine.frostburg.edu/chem/senese/101/features/capsaicin.shtml

http://www.compoundchem.com/2014/01/15/why-chilli-peppers-are-spicy-the-chemistry-of-a-chilli/

http://www.hort.purdue.edu/newcrop/proceedings1996/v3-479.html  

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

http://www.chilepepperinstitute.org/statistics.php

http://www.denverpost.com/news/ci_11066172?source=rss

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

http://www.chilepepperinstitute.org/content/files/MeasuringHeat.pdf

http://www.chilepepperinstitute.org/content/files/bhut_jolokia_worlds_hottest_pepper.pdf

http://www.chilepepperinstitute.org/content/files/trinidad_moruga_scorpion_pepper_hottest.pdf

http://www.chilepepperinstitute.org/content/files/Top%2010%20Hottest%20Chile%20Peppers.pdf

http://abcnews.go.com/Lifestyle/carolina-reaper-peppers-100-times-hotter-jalapeno/story?id=20756069

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

http://www.extension.org/pages/32603/pepper-heat#.UuhF9rTnbIU

http://en.wikipedia.org/wiki/TRPV1

http://www.ncbi.nlm.nih.gov/pubmed/9349813

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

http://www.chilepepperinstitute.org/content/files/Growing%20Tips.pdf