Chocolate Fountain Physics & Jell-O Composition

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Ever looked at a chocolate fountain and wondered why the flowing chocolate slopes inward, instead of falling straight down? Adam Townsend and Dr. Helen Wilson from the University College London developed mathematical equations to explain this sweet, physical phenomenon. If wobbly desserts are more up your alley, take a look at the ingredients list for Jell-O. You may be interested to know that Jell-O contains cowhide.
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Juliet Han

Juliet Han graduated from UC San Diego before moving to Washington D.C. for a music policy internship. She eventually switched to coffee and has now been working in the coffee industry for over a decade. Han has been a judge for regional barista competitions and represented Intelligentsia Coffee in the 2012 U.S. Cup Tasters Championship, where she placed third. Currently, Han is a roaster for Blue Bottle Coffee.

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Image taken from Juliet Han’s Twitter (@JulietintheBae)

What hooked you on coffee?
It hit me one day after years of being a Barista as a side job…I was never bored with it! It was a number of things…the sensory discipline it took to taste coffee (what we call cuppings) to the people in the industry. After 10 years, I’m still learning a lot and having fun.
The coolest example of science in your coffee?
I would say the process of roasting. The process of roasting has barely been studied academically unlike a lot of culinary subjects. So many things are going on when you roast coffee; it’s a volatile process with complicated aromas and many variables to consider.
The food you find most fascinating?
Mushrooms…the way they grow, their flavors, texture, everything about it.
What scientific concept–coffee related or otherwise–do you find most fascinating?
I’m studying chemistry right now, so the idea of matter. Everything around us is basically matter comprised of atoms and molecules. It’s that simple, and so complicated. On my first day of class, there was an article of “Chemistry of Roasting” on the bulletin board about the chemicals that are released in the process of roasting; I can’t wait to read it again after I finish this class to make some sense out of it.
Your best example of a food that is better because of science?
Dairy, especially milks and cheese, but that’s a whole new world I’m scared to explore.
How do you think science will impact your world of coffee in the next 5 years?
Science will impact coffee tremendously as it is slowly starting to already. Coffee is a global agriculture/commodity, a cultural phenomenon and a staple beverage in many countries’. More and more, I’m reading about universities developing “studies” for coffee that vary in topic. From coffee varietals to understanding water temperature, the value of science needed in the coffee community is at a higher demand.
One kitchen tool you could not live without?
My Brita water pitcher—LA water is not the tastiest.
Five things most likely to be found in your fridge?
Eggs, salsa, carrots, onions, baking soda
Your all-time favorite ingredient? Favorite cookbook?
I put Tapatio on most everything. I would put it in coffee if I thought it would make it taste better. Cookbooks, do online publications count? I’m a huge fan of SmittenKitchen.com and ThugKitchen.com.
Your standard breakfast?
Coffee, then followed by whatever I can find (day old pastries, yogurt, bananas) unless it’s a big coffee tasting day…then I will make sure to eat a lot of bland carbs so I don’t lose my mind an hour into tasting.

Space Whisky & “Natural Foods”

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A vial of unmatured malt whisky was sent into space three years ago, and has recently returned to Earth for a taste test. This space whisky was compared to the same whisky that was matured (on Earth) in charred oak barrels. Guess which whisky contains aromas of antiseptic smoke and rubber. While we’re comparing two things, AsapSCIENCE discusses the chemicals and ingredients in processed foods versus natural foods to explain why “chemical-free” is not a realistic food label.
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Anatomy of a hot chocolate

Photo credit: Flickr/louish

Hot chocolate: it’s a winter staple. Amidst falling temperatures and dreary skies, there’s nothing quite like taking a swig of this sumptuous beverage and seeking warm refuge in the delights of a steaming mug. Hot chocolate is as straightforward as drinks go: at its core, it’s milk, cocoa powder, and sugar. Despite its simplicity, this cold-weather classic is swirling with science.

The backbone of any decent hot chocolate is milk. Beyond water, milk is perhaps the most basic and familiar substance to humans. We’re all born drinking some form of it, but how often do we stop and think about its underlying science?  Milk is an emulsion, which is a mixture of two immiscible liquids—in this case, water and fat.   The water-based component of milk is loaded with vitamins, minerals, and protein and contains immiscible fat globules suspended throughout. How do water and fat coexist peacefully in solution together? The answer lies in emulsifiers, which are molecules that are both water- and fat-soluble. Milk contains proteins, namely casein, that attract and unite the fluids that would otherwise separate. Rich, silky, and chemically intriguing, this dairy product serves as the perfect vehicle for chocolate (1).

 

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Photo credit: Flickr/chocolatereviews

Chocolate serves as the heart of the beverage. Some recipes call for it in the form of cocoa powder. Cocoa powder mixed in with your milk is a colloid—a type of mixture in which solid particles are dispersed throughout a fluid. Another popular culinary colloid you may recognize is coffee, which contains small coffee particles dispersed in water.

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Photo credit: Flickr/csb13

A glass of hot chocolate simply isn’t complete with a dollop of whipped cream plopped on top. Lauded for its decadent mouthfeel, cream is an emulsion of butterfat and water, similar to milk but with a higher fat content. Fresh milk left undisturbed will separate into two layers; the top becomes enriched with fat globules that can be skimmed off as cream, leaving behind a relatively fat-free layer—skim milk. Cream and milk have remarkably different fat contents, as cream is required to have at least 30% milk fat compared to whole milk which is a mere 3%.

With some simple agitation, willpower, and a whisk, we can transform heavy cream into whipped cream, a culinary foam. Similar to emulsions, foams combine two immiscible substances, but instead of water and fat, air or gas is entrapped within a fluid or solid. Whisking incorporates air into the cream, and the newly introduced bubbles are held captive by the structure of the foam. Fluids and gases have very different properties, so how does agitation keep them together?  Agitation disorients the fat globules and strips away their protective membranes, forcing them to cling to other fat molecules or aggregate around air bubbles—anything to avoid having to be in contact with water. Agitate your cream enough and you’ll wind up with stiff peaks when these fat-encapsulated air bubbles begin to form a stable network (2).

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Photo credit: Flickr/knitsteel

Whether they’re being roasted over a campfire or floating lazily on the surface of your hot chocolate, marshmallows are a surefire way to please and are another way to enhance your chocolate-drinking experience. Marshmallows were originally made as a meringue (yet another culinary foam!) consisting of whipped eggs and sugar flavored with the juice from roots of the marsh mallow plant. The making of marshmallows has since evolved so that now they are created by aerating a mixture of simple sugar syrup and gelatin to form a foam that stabilizes once the gelatin sets. Whipping incorporates air bubbles that are trapped in the solid matrix, forming these springy and sugary confections that pair exceptionally well with chocolate (1).

Hot chocolate is the ultimate winter beverage. It’s creamy, decadent and versatile. Drink it plain or spice it up with some chili powder, orange, or peppermint and you’ll surely find a style that will leave you positively foaming at the mouth.

References cited

    1. McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004. Print.
    2. Lower, Claire. Cream Science: On Whipping, Butter, and Beyond. Serious Eats. 2014.

Mai NguyenAbout the author: Mai Nguyen is an aspiring food scientist who received her B.S. in biochemistry from the University of Virginia.

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Stinky Tofu

You may be familiar with stinky tofu’s strong, pungent odor that makes you wrinkle your nose in disgust. Although this dish certainly lives up to its name, taking a bite into its crunchy, deep-fried exterior that gives way to warm, firm tofu might just make you a stinky tofu convert. A popular street food in Taiwan, Hong Kong, and parts of China, stinky tofu is a fermented tofu dish that is often deep-fried, drizzled with a salty sauce, and served with a side of pickled vegetables. This dish can also be found simmered in spicy hot pot, grilled on skewers, and mixed into rice porridge. So what is the secret to its stink?

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Stinky tofu from Luodong township in Yilan, Taiwan.

It starts with the brine used to ferment the tofu. The conventional process involves adding shelled shrimp and vegetables such as bamboo shoots and Chinese green cabbage to salt water in wide mouth jars. These jars are then exposed to air for several months to allow the brine to undergo natural microbial fermentation that results in its unique stinky smell. Bricks of tofu are then soaked in the liquid for 4-6 hours to develop its flavor [1].

The major bacteria strains that that contribute to the fermentation process include Bacillus sphaericus, Enterococcus gallinarum, Acinetobacter spp., and Corynebacterium spp. [1]. Microbes of the Bacillus genus secrete proteases that hydrolyze, or break down, the tofu proteins into their constituent amino acids (aka the building blocks of proteins) and peptides (molecules made of multiple amino acids) [2]. Two important sulfur-containing amino acids, cysteine and methionine, degrade during the fermentation process and form various sulfides that are responsible for those sulfurous, meaty, and onion odors [3].

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Stinky tofu that have been marinated and are ready for deep-frying

If that is not stinky enough, the volatile flavor compound that contributes most to stinky tofu’s smell is indole, which is associated with fecal and animal odors. Less potent flavor compounds include esters, alcohols, aldehydes and ketones, which confer sweet and fruity odors. In fact, a research study analyzing volatile flavor compounds in a sample of fermented stinky tofu identified a total of 39 compounds that contribute to its smell [3]. Considering how molecules become even more volatile when heated (diffusion speeds up with higher temperatures), helps to further explain why you get a burst of stinky odor when stinky tofu is deep-fried [4].

Stinky tofu definitely lives up to its name, but don’t let the smell deter you from trying the dish. After all, if you end up loving it you will never have trouble finding a stinky tofu stand if you just follow your nose!

References cited

  1. Chang, H., Wang, S., Chen, J., & Hsu, L. “Mutagenic Analysis of Fermenting Strains and Fermented Brine for Stinky Tofu.” Journal of Food and Drug Analysis. 9.1 (2001): 45-49. Web.
  2. Stinky tofu. Microbe Wiki.
  3. Liu, Y., Miao, Z., Guan, W., Sun, B. “Analysis of Organic Volatile Flavor Compounds in Fermented Stinky Tofu Using SPME with Different Fiber Coatings.” 17 (2012): 3708-3722. Web.
  4. Hui, Y.H. (2007). Handbook of Food Science, Technology, and Engineering (Vol. 4). Hoboken, NJ: Wiley & Sons, Inc.

 


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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Futuristic Cranberries & 1959 Cranberries

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In the future, cranberries may be sweet enough to snack on without sugar, thanks to the efforts of biologists and geneticists at the University of Wisconsin-Madison. Going back in time to 1959, a few cranberry batches tested positive for aminotriazole, an herbicide, causing a nationwide panic and collapsing the cranberry industry almost overnight.
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Maple Syrup

Photo credits: flickr/Doug

Photo credits: flickr/Doug

Nothing sets the tone for a drowsy Sunday afternoon like a breakfast that features maple syrup. This sticky and wonderful syrup fills the nooks and crannies of our nation’s waffles with the taste of autumn and the smell of Canada. Let’s take a moment to appreciate the science that makes maple syrup and its confectionery relatives the crown jewel of breakfast condiments.

Generally, syrups are made by extracting sap from plants and boiling them down so they become a more concentrated and viscous liquid. The sugar maple tree, Acer saccharum produces the sap that can eventually become maple syrup, as it produces sap in greater quantities than other maple varieties.

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Optimal conditions for sap harvesting involve extreme temperature fluctuations from day to night. The northeastern United States and eastern Canada, of course, have just the night-day temperature shifts to produce quality maple sap. The traditional sap-seeker drills a small hole into the cambium, or woody tissue, of a maple tree, and inserts a spout. On warm days when temperatures are above freezing, the liquid sap expands and creates positive pressure in the xylem – the plant version of veins; this pressure pushes sap out of the tap hole and into the collection vessel. When night falls and temperatures drop below freezing, sap contracts as all liquids do when chilled. As the sap contracts, this creates negative pressure, which sucks water from the soil into the roots and the tree; this replenishes the sap that has bled out of the tap hole.

Photo Credits: flickr/Chiot's Run

Photo Credits: flickr/Chiot’s Run

After harvesting, the harvested sap is boiled down until it has a viscosity of about 150-200 centipoises – a viscosity very similar to that of motor oil. When the liquid has reached this consistency, it has undergone a 40x reduction in volume. The resulting syrup is approximately 62% sucrose, 34% water, 3% glucose and fructose, and 0.5% malic acid, other acids, and traces amounts of amino acids. The distinct and lovely aromatic notes of maple come from wood byproducts like vanillin, other products of sucrose caramelization, and products of Maillard reactions between the plant sugars and the amino acids.

Photo Credits: flickr/LadyDragonflyCC

Photo Credits: flickr/LadyDragonflyCC

Another delectable treat from Northern climates is maple sugar. Maple sugar is made by boiling maple syrup (which has a boiling temperature 25-40°F above the boiling point of water, but varies with altitude) to increase sucrose concentration, then letting the syrup cool. Left alone, the sucrose accumulates into coarse crystals that are thinly coated with the remainder of the syrup. Simply put, maple sugar is plain table sugar with a natural coating of maple flavor.

Photo Credits: flickr/cdn-pix

Photo Credits: flickr/cdn-pix

A luxury to smear on your toast or pancake, maple cream is surprisingly simple to make, and despite its name, doesn’t contain any dairy. This delicious creamy spread is a malleable mixture of very fine crystals that are dispersed in a small amount of syrup. Maple cream is made by cooling maple syrup rapidly to 70°F by immersing its container in ice water, then beating it continuously until it becomes very stiff; thereafter it is warmed until it becomes smooth and has the texture and viscosity of a runny buttercream frosting.

Photo credits: flickr/ Anne White

Photo credits: flickr/ Anne White

One last note on maple syrup – beware of imposters! If the bottle doesn’t say maple syrup, it is not maple syrup. Breakfast or pancake syrup disappointingly consists of corn syrup and artificial flavors.

Works Cited

  1. “Learn about the Science of Maple Syrup.” Cary Institute of Ecosystem Studies. N.p., 24 Mar. 2013. Web. 25 Nov. 2015.
  2. McGee, Harold. “Sugars and Syrups.” On Food and Cooking: The Science and Lore of the Kitchen. 1st ed. New York: Scribner, 2004. N. pag. Print.
  3. “Viscosity Comparison Chart.” Viscosity Comparison Chart. The Composites Store, n.d. Web. 25 Nov. 2015.

Elsbeth SitesAbout the author: Elsbeth Sites received 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.

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