Soda Consumption & Fat Perception
Researchers at University of Alaska analyze carbon isotopes to measure soda consumption, while German scientists study how our psychological state affects how we taste and perceive fat.
Researchers at University of Alaska analyze carbon isotopes to measure soda consumption, while German scientists study how our psychological state affects how we taste and perceive fat.
In his lecture Primitive X Modern, Chef Alex Atala questioned our cultural interpretations of what is “edible” or “delicious” by feeding us Amazonian ants. It turns out that insects aren’t the only controversial “food” in the culinary world—Smithsonian Magazine uncovers an unexpected ingredient in beer, while NPR explores the world of in vitro (i.e. test tube) meat. Read more
It turns out that giving fruits and veggies a good night’s sleep isn’t the only way to make them better to eat. Researchers at Texas A&M have shown that carrots produce more antioxidants in response to the “stress” of being chopped or shredded, while scientists at the University of Florida are working hard to make a tastier and more nutritious tomato. Read more
In 400 BCE, the Greek admiral Androsthenes wrote* of a tree that
“opens together with the rising sun . . . and closes for the night. And the country-dwellers say that it goes to sleep.”
Over the next 2000 years, researchers discovered that the daily cycles first observed by Androsthenes fall into 24-hour periods similar to our own cycles of waking and sleeping [1]. In plants, these circadian rhythms help control everything from the time a plant flowers to its ability to adapt to cold weather [2]. Plants can even use their internal clocks to do arithmetic calculations to budget their energy supplies through the night [3].
But what happens when part of a plant is harvested for food? In a recent study, researchers at Rice University and UC Davis showed that cabbages can exhibit circadian rhythms as long as a week after harvest.
As with any plant, cabbages experience circadian rhythms while growing out in the field; however, cabbages stuck in the constant dark of a delivery truck or light of a 24-hour grocery store will inevitably lose their sense of time. Like travelers adjusting to a new time zone, cabbages deprived of cyclic light conditions suffer a severe bout of veggie jet lag. And just as travelers overcome jet lag by readjusting their sleep cycles, cabbages can “re-entrain” their circadian rhythms by being exposed to cyclic light conditions. This also works with spinach, zucchini, sweet potato, carrots, and blueberries, suggesting that post-harvest circadian rhythms are a general characteristic of many, if not all, fruits and vegetables.
The ability to re-entrain circadian rhythms in produce presents an intriguing new way to improve the palatability and even nutrition of our fruits and vegetables. In the wild, circadian rhythms can help plants defend themselves against hungry herbivores. The researchers showed that cabbages with re-entrained circadian rhythms use a similar mechanism to avoid becoming an afternoon snack for plant-eating larvae—with less damage from hungry larvae, re-entrained cabbages appear fresher and tastier than cabbages kept under constant light or dark conditions.
Cabbages fight off larvae and other pests thanks to molecules called glucosinolates. Any cabbage can produce these molecules, but re-entrained cabbages produce glucosinolates in sync with their circadian rhythms. Because larvae also experience circadian rhythms, re-entrained cabbages get an extra boost of molecular larvae-fighting power just when they need it the most.
While glucosinolates are bad news for larvae, they have valuable anti-cancer properties when consumed by humans. In fact, the very molecules that plants create to defend themselves against their environment are often beneficial for our own health. Future research will show whether such phytonutrients in other types of produce can also be reconditioned to accumulate in predictable 24-hour cycles. Taking advantage of circadian rhythms in fresh produce could then give us more control over the way phytonutrients accumulate over time, helping us maximize the nutritional benefits of our fruits and vegetables. Improving the nutrition of our food could be as simple as giving our produce a good night’s sleep.
*The original Greek passage comes from Botanische forschungen des Alexanderzuges [4] with a very special thank you to Tovah Keynton for the English translation. The drawings (also from Botanische) depict the tree leaves transitioning into and then assuming their “sleeping position.”
References Cited
About the author: Liz Roth-Johnson is a Ph.D. candidate in Molecular Biology at UCLA. If she’s not in the lab, you can usually find her experimenting in the kitchen.
Author Jo Robinson explores the agricultural history of phytonutrients, while Harvard researchers move us a step closer toward understanding how the resveratrol in red wine and chocolate could be hindering the aging process. Read more
Rachel Dutton is a Bauer fellow at Harvard University where she uses cheese to study microbial ecosystems. She has collaborated with chefs David Chang and Dan Felder of Momofuku, and her research has been featured in Lucky Peach Magazine, The Boston Globe, NPR, The New York Times, and on the PBS TV series Mind of a Chef.
Have you ever been offered a fancy cheese that smelled more like a used gym sock than something edible? Odor artist Sissel Tolaas and researcher Christina Agapakis took this idea and ran with it, with their project Synthetic Aesthetics. The duo used bacteria isolated from human hands, feet, noses, and armpits to generate cheese!
Many cheeses, like beer, wine, and yogurt, are the product of fermentation. Fermentation occurs when microorganisms such as yeast and bacteria convert carbohydrates such as sugar into alcohols, gasses, and acids to generate energy in the absence of oxygen. One common cheese-making type of bacterium, Lactobacillus, breaks down lactose, the primary milk sugar, to lactic acid. This results in lowering the pH of the milk, which as pointed out in a previous post, causes coagulation and solidification into cheese. The work of microorganisms in cheese also results in the creation of many other byproducts that give cheeses their unique smell, texture, and flavor profiles. For example, the bacterium, Propionibacterium freudenreichii, generates carbon dioxide gas in the process of making swiss cheese and causes its characteristic holes [1]. Penicillium roqueforti, which is related to the fungus that helps produce the antibiotic, penicillin, gives blue cheese it’s distinct aroma and look [1].
Microorganisms that use fermentation are found everywhere. Tolaas and Agapakis realized that the human body shared many characteristics with the environments for creating cheese. On a hot day or before a hot date, your armpits may be just as warm and moist as an industrial cheese incubator. Furthermore, cheese-making bacteria like Lactobacillus are common inhabitants in the mammalian gut [1]. With this information, they isolated bacteria from hands, feet, noses, and armpits and added them to whole milk to serve as starter cultures.
Figure 2. Samples prepped for the smell survey. Participants of the survey were asked to smell the samples and provide a description of the odors they detected. |
Here are the results:
Source | Bacteria | Isolated Odors |
Hand-1 | Providencia vermicola Morganella morganii Proteus mirabilis |
yeast, ocean salt, sour old cheese, feet |
Foot-1 | Providencia vermicola Morganella morganii Proteus mirabilis |
sweat, big toe nail, cat feet, sweet, milky, orange juice in the fridge too long, fungus, buttery cheese, soapy, light perfume |
Armpit-1 | Providencia vermicola Morganella morganii Proteus mirabilis |
Feta cheese, Turkish shop, nutty, fruity, fishy |
Nose-2 | Providencia vermicola Morganella morganii Proteus mirabilis |
cheesy feet, cow, cheese factory, old subway station, toilet cleaner |
Armpit-2 | Enterococcus faecalis Hafnia alvei |
neutral, perfumed, industrial, synthetic, fermentation, car pollution, burning, sharp, chemical |
Armpit-3 | Micobacterium lactium Enterococcus faecalis Bacillus pumilus Bacillus clausii |
neutral, sour, floral, smooth, yogurt |
Foot-5 | Providencia vermicola Proteus mirabilis |
yeast, jam, feet, putrid, sour, rotten |
Armpit-4 | Enterococcus faecalis | yogurt, sour, fresh cream, butter, whey |
The cheeses displayed a diverse range of bacterial species and odors. Interestingly while some cheeses smelled like “old subway station” or “cat feet,” others exuded the familiar & appetizing flavors of “yogurt,” “feta cheese,” and “light perfume.” Furthermore, some of the bacteria isolated were common to various cheeses. For example, Enterococcus faecalis is a lactic acid bacterium found in raw milk and cheeses, like farmhouse cheddar varieties [2]. Proteus mirabilis is related to Proteus vulgaris, which is responsible for giving surface-ripened cheeses like Limburger and Munster a strong aroma [3].
While these bacterial cultures may not serve as the basis of a new type of artisan cheese, Agapakis notes:
“These cheeses are scientific as well as artistic objects, challenging us to rethink our relationship with our bacteria and with our biotechnology. . . . The cross-over between bacteria found on cheese and on human skin offers a tantalizing hint at how our bacterial symbiotes have come to be part of our culinary cultures.”
In the face of diminishing resources, we are reminded that untapped reservoirs, which may be literally under our noses, might contain hidden treasures that could change the way we generate and produce food.
Online Resources
References cited
About the author: Vince C Reyes earned his Ph.D. in Civil Engineering at UCLA. Vince loves to explore the deliciousness of all things edible.
Imagine taking a bite of your favorite food. Is it sweet? Salty? Does it have a sour bite or a hint of bitterness? Maybe even a touch of savory umami?
Every time we eat, our taste buds sample these five basic taste qualities. Taste receptors decorating the surface of each taste bud interact with specific molecules; the corresponding flavor sensation then gets sent to your brain. Umami receptors, for example, sense the molecule glutamate. When free glutamate in our food—either naturally occurring or from added MSG—interacts with an umami receptor, we taste a delicious savory flavor.
Although glutamate is the primary source of umami flavor, certain molecules called nucleotides can enhance the umami sensation. Because nucleotides make up the genetic material (DNA and RNA) of all living things, nucleotides are ubiquitous in many of the foods we eat. Nucleotides themselves cannot activate umami taste receptors, but they can intensify the umami sensation caused by glutamate. Intrigued by this phenomenon, scientists Ole Mouritsen and Himanshu Khandelia recently published a paper exploring how one nucleotide, guanosine-5ʹ-monophosphate (GMP), might work together with glutamate to activate umami taste receptors.
Only one of the three known umami taste receptors can interact with both glutamate and GMP. This so-called “T1R1/T1R3” receptor switches between two states: an “off” state when no glutamate is present and an “on” state when glutamate is attached to the receptor. To understand how GMP might affect these two states, Mouritsen and Khandelia ran a series of computer simulations testing the receptor’s behavior in the presence or absence of GMP. As expected, glutamate caused the receptor to exist in the “on” state more than the “off” state. When GMP was added to the simulation, both GMP and glutamate interacted with the receptor to further stabilize the “on” state.
Besides providing a compelling molecular model for umami taste sensation, this and future work on taste receptors may help us become more savvy seasoners in the kitchen. Because umami taste receptors are similar to the taste receptors for sweet and bitter, understanding how molecules like GMP enhance umami sensations can help us develop enhancers for other taste sensations. Just as GMP makes glutamate taste more intensely umami, a sweet enhancer could make sugar taste sweeter with no added calories. Identifying more taste enhancing molecules like GMP could bring a whole new dimension to the way we cook in the future. Forget about salt and pepper—the flavor enhancers are coming.
About the author: Liz Roth-Johnson is a Ph.D. candidate in Molecular Biology at UCLA. If she’s not in the lab, you can usually find her experimenting in the kitchen.
Veronica Trevizo is the Development Chef at Momofuku Culinary Lab. Veronica hails from California, where she was born in San Diego, attended the California Culinary Academy, and worked at such venues as the Four Seasons in San Diego and the San Francisco establishments Jardinière and Michael Minas. She also spent time working at Spagos in Maui and has worked all over Europe, completing stages in Spain and at Noma in Copenhagen, before relocating to New York to work in the Momofuku Culinary Lab.
Daniel Felder is the Head of Research and Development at the Momofuku Culinary Lab. Dan is originally from Roxbury, Connecticut, and began working in restaurants at the age of eighteen while he was studying at Union College in Saratoga Springs, New York. He moved to New York City and joined the Momofuku team in 2008 at Noodle Bar and Ko, and now at the Momofuku Culinary Lab.