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Strawberry Sweetness & Walnut Antioxidants

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Good news for strawberry & walnut lovers! Researchers at UC Davis and the University of Florida are studying the strawberry genome in order to breed a strawberry that has both shelf life and that fresh-off-the-vine sweetness. At the University of Scranton, Joe Vinson, Ph.D., analyzed nine different types of nuts for antioxidant levels, and walnuts came out as the winners.
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Blood Orange

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While traditional oranges are available at your local supermarket all year long, the best time to enjoy the juicy, crimson flesh of blood oranges is during these winter months. So while you venture out for some delicious blood oranges, consider these fascinating tidbits. How do they get their characteristic color? How are they different from everyday oranges?

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

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Cranberry

Cranberries are harvested in late autumn, just in time to celebrate the holidays. Whether you prefer to enjoy cranberries in a jam, as a sauce from the can, juiced, dried, or fresh, there’s no denying that cranberries are festive. They’re tart, dark red, and pair really well with a turkey dinner (according to science). Read more

Nutmeg

Nutmeg is a key note in October comfort favorites such as pumpkin spice lattes and spiced bread. The spice is warm, sweet, and spicy, perfect for the gradually colder days of autumn. Take a closer look at nutmeg, however, and you might find a disquieting surprise. Are you prepared to take a whiff of nutmeg science? Read more

Meat: where physiology meets flavor

A charcuterie board is the perfect accompaniment to any gathering and rivals a cheese plate as a crowd-pleaser. It’s low maintenance, delicious, and will almost certainly have a taste or texture to appeal to the pickiest of palates. Meat comes in an array of textures, fat content, and flavors, which vary species to species and even within the same animal. Flavor profiles of meat can vary wildly and subtleties between different cuts of meat can all be largely explained by chemistry.

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Photo credit: willmacdonald18 (Flickr)

What is meat exactly? Meat can loosely mean any type of edible tissue originating from an animal – including everything from chicken feet to cow tongue. The majority of meat we consume, however, is skeletal muscle tissue, comprising roughly 75% water, 20% protein, and 3% fat. While the function of muscle tissue—which is to generate movement—is simple, muscle tissue is a complex system of biochemical machinery.

Muscle tissue consists white and red fibers, which each generate contrasting types of movement. The major differences between the two types of muscle fibers are summarized in the table below.

red muscle fibers white muscle fibers
alternate names slow-twitch fibers fast-twitch fibers
relative size thin thick
movement type prolonged, deliberate short, high-powered bursts
fueled by fat + oxygen glycogen
Requires oxygen? absolutely yes, but can run anaerobically
taste/nutrtion fattier, more flavorful higher in protein, relatively bland
appearance dark/red white

The main distinction between these types of tissue is in their function and metabolic demands. Red muscle fibers are designed for endurance—think long distance running—or sustained motion. Red tissue runs on fat and oxygen and absolutely requires oxygen to function properly. Since red muscle tissue demands oxygen, it contains an abundance of a pigmented protein called myoglobin. Myoglobin binds and stores oxygen from the then passes it along to a fat-oxidizing cytochrome that generates ATP to fuel the cell. The more exercise a muscle receives, the higher its demand for oxygen, and the more myoglobin and cytochromes it will contain, leading to a darker appearance.

duck meat

Photo credit: Harlanh (Flickr) Duck breast – an example of dark meat

White muscle fibers, on the other hand, are specialized for more sporadic and brief energetic demands. These tissues use oxygen to burn glycogen, but can also produce energy anaerobically if needed. However, anaerobic metabolism results in the buildup of lactic acid and limits the endurance of these tissues, which is why they can only be used for short periods. White muscle fibers, unsurprisingly, are what comprise white meat—chicken breast, turkey breast, frog legs, and rabbit meat.

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Photo credit: allthingschill (Flickr) Turkey breast

The link between structure, function, and taste can be used to answer the question of why chickens and turkeys have a combination of dark and white meat, but why ducks and geese are all dark meat. They’re all birds, after all, so it’s rather surprising that there’s such a drastic difference in their breast meat, until you consider their habits. Chickens and turkeys are relatively flightless birds. They stand, walk, or run, and use their legs to bear their weight. Their constantly used legs are mainly dark meat and their infrequently used breasts are composed of white meat. Duck and geese, however, are migratory birds whose flight patterns enlist the use of breast muscles to help them stay airborne for extended periods. To aid them in sustained flights, their chests muscles require increased stores of oxygen and myoglobin, making their breast meat dark, in stark contrast to a chicken or turkey’s breast.

The dichotomy of metabolic demands between red and white meat clearly impacts their physiology, but how does this translate into taste? The complexity of the biochemical equipment needed to store fat and oxygen and metabolize fat in red muscle tissue equates to a higher number of enzymes present in the cell that can break down and produce more flavorful compounds when cooked. A piece of dark or red meat is fattier, boasts richer and more complex flavors, and retains moisture far better than white meat.

How else can chemistry explain the different tastes of meat, ranging from the beefy flavors of cow to the gamey flavors of duck breast? It’s a common saying in the culinary world that where there’s fat, there’s flavor. While fat serves as storage for energy, it doubles as storage for flavor. With fat distributed throughout the meat, any fat-soluble flavor or aroma compounds can end up in them providing meat with its unique flavor profile. What winds up in the fat is heavily influenced by diet – cows taste “beefy” as a result of flavor compounds metabolized from grass and forage. Lamb and sheep’s distinctive flavors come from compounds produced by the liver, and the gamey flavors of duck meat are likely derived from intestinal microbes.

Examining meat through a scientific lens allows us to relate some common mantras of biology, chemistry, and cooking: structure and function go hand in hand, fat is where the flavor is, and you are (and you also taste like) what you eat. In the context of meat, physiology and flavor are intertwined and whether you’re a fan of dark or white meat, you can surely appreciate the fascinating connection between animal physiology and flavor.


References Cited:

  1. McGee, Harold. On food and cooking: the science and lore of the kitchen. New York: Simon & Schuster, 1997. Print.

Mai NguyenAbout the author: Mai Nguyen is an aspiring food scientist who received her B.S. in biochemistry from the University of Virginia. She hopes to soon escape the bench in pursuit of a more creative and fulfilling career.

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Saffron

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Catherine HuAbout the author: Catherine Hu received her B.S. in Psychobiology at UCLA. When she is not writing about food science, she enjoys exploring the city and can often be found enduring long wait times to try new mouthwatering dishes.

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Cotton Candy

Summer would be incomplete without carnivals and bright, fleecy, sugary cotton candy. For a snack that’s nothing but sugar and air, there’s a surprising amount of physics and chemistry involved. Below are seven science-heavy facts about this feathery-light confection.

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Editor’s note: The original post stated that 1 ounce of cotton candy is 0.105 kilocalories, when in fact, it is 105 kilocalories, which is equivalent to 105 Calories. Thanks to our astute reader, Allison of the Internet for catching that! The post has now been updated (08-18-2015 10:06 p.m. PST)


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.

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Coconut

If you’re itching for a tropical getaway, enjoying a coconut snack could help conjure up images of cool sand, blue waters, and swaying palm trees. The coconut tree (Cocos nucifera) and its fruits may very well be the symbol of paradise, since coconut is an ingredient in many Southeast Asian and Pacific Island cuisines. If you find yourself eager to whip up some curry, puttu, Ginataang Manok, macaroons, a cold glass of piña colada, or just feel like sticking a straw into a coconut, take some time to digest a little bit of coconut science before cracking open a coconut. Read more

Flavor-Changing Chewing Gum

Growing up as a chubby kid who tried to convince her parents that candy belonged at every meal (a real life Augustus Gloop, if I may), one of my favorite books was Charlie and the Chocolate Factory. And though I’d dream for a mug of the chocolate river, my favorite of Willy Wonka’s creations was the three-course chewing gum. Tomato soup, roast beef, and blueberry pie in one piece of gum? The possibilities! While you can find some commercial versions of flavor-changing gum at the supermarket today, my fingers are crossed for a three-course meal sometime in the near future.

Image Credit: (stevendepolo/flickr)

Image Credit: (stevendepolo/flickr)

To get any sort of flavor in a chewing gum in the first place, a process called microencapsulation is used, in which a core of tiny flavor particles is surrounded by a shell coating to produce minuscule spherical capsules – we’re talking diameters of roughly a couple hundred micrometers in size [1]. Chewing gums contain these little flavor microcapsules; the core of each microcapsule is usually some sort of liquid flavoring, and the shell is made of crosslinked proteins which stabilize the core material, isolate the core from the chewing gum base, and will break apart in response to the shear forces of chewing to release the core flavoring [1].

So let’s say you have a stick of strawberry-flavored chewing gum. The gum will be studded and mixed with microcapsules filled with strawberry flavoring oils; those are the beady dots you sometimes see on the chewing gum surface. The fruity flavor is released once you chew on the gum and break open the shells of the strawberry capsules to release the flavoring oils in your mouth.

microencapsulated flavor droplet

While there are various methods for flavor encapsulation, the technique which is used to make the capsules in chewing gum is the chemical process called complex coacervation. [4] This process involves an aqueous solution with two or more oppositely charged polymers – one with positive charge (such as gelatin or agar), and another with negative charge (such as carboxymethylcellulose or gum arabic) [2]. These two polymers are diluted into water and then controlled for both pH and temperature, so that when an oily substance (such as a flavoring oil) is mixed into the solution, the molecules form a chemically crosslinked, shell-like film around each of the oil particles, resulting in the encapsulated flavor beads present in chewing gum!

The coacervation solution then separates into two liquid phases – one called a “coacervate” that contains the many tiny oily droplets that contain the polymers and the other is called the “equilibrium liquid”, which serves as the solvent. Once the shells around the oil droplets are formed, the rest of the solution is washed out and the entire capsules are dried so that they can be incorporated into the chewing gum base [3].

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The Coacervation Process: (a) The oily flavor droplets float around in an emulsion of the shell polymer solution, (b) The coacervation solution separates into the coacvervate and the solvent (c) The coacervate surrounds the outside of the flavor core, (d) And forms a continuous crosslinked polymer shell around the core.

So how does the flavor-changing gum work? The secret lies in the fact that the tiny flavor capsules in a chewing gum can be engineered to release at different times. By creating microcapsules with different dissolution times, the release of several different flavor capsules can be staggered to make a chewing gum that “changes flavors”. The first flavor composition in a flavor-changing gum is usually the unencapsulated liquid flavor or a starch sugar coating on the surface of the gum, so that the first flavor can be released on contact with saliva [4].

After the initial flavor perception, the second, third, fourth, and any subsequent flavors will be encapsulated, but with varying materials in the cores and shells, so that each flavor is released at a different time during the gum-chewing experience. The goal for a flavor-changing chewing gum is to have its flavors release quickly and intensely, preferably 15 to 45 seconds after the release of the previous flavor [5]. The release times of the microcapsules can depend on a variety of factors involving both the core flavoring substance and the encapsulating materials:

  • Solubility of Flavoring Substance
    Water-soluble flavoring substances are more soluble in our saliva, so they are released in chewing gum before the oil-soluble flavoring substances. Water-soluble flavors include vanilla, synthetic fruit flavors like cherry and lemon, and plant extracts such as coffee and licorice. Oil-soluble flavors include cinnamon oil, peppermint oil, peanut butter flavor, chocolate, and eucalyptus oil [5].

  • Hydrophobicity of Capsule Shell
    Microcapsule shells made of highly hydrophobic proteins, meaning they have low water-absorption properties, take longer to release the core flavor. Meanwhile, shells that are made with less hydrophobic material, which can absorb more water, release the flavor components earlier and more quickly. For example, if we use ethylene-vinyl acetate as the shell material, the release rate can be controlled with a few adjustments. A higher ratio of ethylene to vinyl acetate creates a more hydrophobic shell, which results in a slower release of flavor. On the other hand, using lower ratio of ethylene would create a less hydrophobic shell and a quicker release of flavors [5].

  • Tensile Strength in Microcapsules
    The maximum amount of stress that the encapsulation shell can withstand from chewing before it breaks and releases the core flavor is called the tensile strength. Changing the tensile strength of each flavor’s shell can determine the order in which the flavors are perceived. Materials that lower the shell’s tensile strength are fats, plasticizers, waxes, and emulsifiers, so adding these materials into the shell of a flavor capsule causes it to break more easily and release flavors more quickly [5]. Meanwhile polymers with high molecular weight tend to increase the tensile strength of the shell, so these flavors are released later, since they require more vigorous chewing.

A combination of these factors from hydrophobicity to tensile strength can be used to determine the order of the flavors released for an entire three-course meal (or more!) in just a stick of gum. Tomato soup, roast beef, and blueberry pie, here I come!

Image Credit: (pinkiepielover63/deviantart)

Image Credit: (pinkiepielover63/deviantart)

References Cited:

  1. J. Sris, A. Seethadevi, K. Suria Prabha, P. Muthuprasanna, and P. Pavitra. (2012). Microencapsulation: a review. International Journal of Pharma and Bio Sciences. 3: 509–521.
  2. Feng T., Xiao Z., Tian H. (2009). Recent Patents in Flavor Microencapsulation. Recent Patents on Food, Nutrition, & Agriculture. 1:193–202.
  3. Xiao Z., Liu W., Zhu G., Zhou R., Niu Y. (2014). A review of the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology. Journal of the Science of Food and Agriculture. 94: 1482-1494.
  4. Gaonkar A.G., Vasisht N., Khare A.R., Sobel R. (2014). Microencapsultion in the Food Industry: A Practical Implementation Guide. Academic Press. 421-453.
  5. Lenzi S., Kar S., Michaelidou T.A., and Harvey J.E. (2012). Chewing Gum Compositions Providing Flavor Release Profiles. Kraft Foods Global Brands LLC, assignee. Patent WO2012034012.

Eunice LiuAbout the author: Eunice Liu is studying 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


Pistachio

They’re green, nutty, and floral, the perfect summer combination. Pistachios are used in many summertime favorites around the world, from can’t-get-enough-of-‘em Turkish delights to the Indian Subcontinent ice cream kulfi to the Italian frozen dessert spumone. They’re even perfect for cracking open for snacking while watching the ballgame. If pistachios aren’t the quintessential summer flavor, here are seven reasons why they should be: Read more