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Inside the Experimental Cuisine Collective

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Robert Margolskee, Mitchell Davis, Florence Fabricant, Wylie Dufresne, and Hervé This at the Experimental Cuisine Collective’s launch workshop on April 11, 2007. Photo credit: Antoinette Bruno (Star Chefs)

 

Launched in 2007, the Experimental Cuisine Collective (ECC) has proven itself as an invaluable resource for those interested in learning about the scientific principles behind food. Founded by Drs. Kent Kirshenbaum and Amy Bentley of New York University in collaboration with Chef Will Goldfarb of WillPowder, the ECC hosts workshops approximately five times per year, each featuring different topics and/or speakers. ECC’s current Director is Anne McBride, a PhD candidate in Food Studies at NYU and Culinary Program/Editorial Director for the Culinary Institute of America. Widely recognized for her ability in establishing connections between scientists and chefs, McBride has been instrumental in developing ECC’s programs. ECC’s workshops have gained nationwide acclaim, featured in media outlets such as Serious Eats, New York Observer, and even the Food Network!

The impressive roster of past ECC speakers include renowned chefs and scientific minds such as Dan Barber, Wylie Dufresne, Rachel Dutton, and Mark Bomford. The topics of ECC workshops are also interestingly diverse, covering topics from soda politics with Marion Nestle to cooking insects with the Yale Sustainable Food Project to the New York Academy of Medicine’s Eating Through Time conference.

Our recent Science & Food public event featured Dr. Kent Kirshenbaum , who stopped to answer a few questions for us about the ECC:

What motivated you to start the Experimental Cuisine Collective?
I was asked by the National Science Foundation to consider establishing a science outreach program as part of their emphasis on “Broader Impacts” of scientific research. I’ve always been eager to establish connections between scientists and experts from other disciplines, so exploring the terrain between chemistry and cuisine came about very naturally.
What has been one of your most memorable experiences since founding the site?
The Experimental Cuisine Collective has always been more about direct engagement rather than as a web-based portal for information. One of my most memorable experiences with the ECC was preparing an alginate-based mango-juice pearl with a 4th grade student at a science fair.  I asked her if we were doing science or cooking. After a moment’s careful thought she replied, “I guess it’s both!” That was a very satisfying moment.

Another memorable experience was giving a lecture series about the ECC throughout New Zealand during the “International Year of Chemistry”. The director of the ECC, Anne McBride, and I got the chance to prepare what we believe were the world’s first vegan pavlovas for our audiences throughout New Zealand. We love Kiwis!

What do you hope the Experimental Cuisine Collective’s readers take away from the website?
I think they are excited about the lecture programs we are offering at NYU, and the opportunity to learn what science can contribute to cooking — along with how chefs can advance scientific objectives. Plus, I hope readers are quick to appreciate that we have been offering our programs for almost 10 years, and all of it has been completely free of charge!
Are there any upcoming projects you would like people to know about?
Our upcoming meeting will be devoted to hydroponic farming, in partnership with the Institute of Culinary Education. We will be meeting at ICE’s indoor 540-square-foot farm in lower Manhattan, designed by Boswyck Farms, which has 3,000 plant sites and in which 22 crops are currently growing. The amazing thing about this farm is that it is literally across the street from the tallest building in the Western Hemisphere. Science can help us grow in so many ways and places!

Ashton YoonAbout the author: Ashton Yoon received her B.S. in Environmental Science at UCLA and is currently pursuing a graduate degree in food science. Her favorite pastime is experimenting in the kitchen with new recipes and cooking techniques.

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From Field to Fork: Food Ethics for Everyone – An Excerpt

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 “You are what you eat.”

This aphorism is consistently used to fit different scenarios, but are we really what we eat? Author Paul B. Thompson begs to differ. In his book, From Field to Fork: Food Ethics for Everyone, Thompson presents his case against this statement and brings light upon many ethical food dilemmas, including obesity, livestock welfare, and the environmental impact of food systems. He structures his thoughts around the idea that food ethics are being revived in the contemporary world. Regarding the aforementioned axiom, Thompson explains that food is more than just substance for your body’s functioning. Here is an excerpt analyzing this issue:

“On the one hand, dietetics has become a domain of personal vulnerability calling for regulatory action on moral grounds. What is vulnerable may be one’s health, as in the case of food safety or nutrition, but it may equally be one’s identity or solidarity with others as people attempt to achieve social justice and environmental goals through labels that promise ‘fair-trade’ or ‘humanely raised’ foods. On the other hand, practices that promote hospitable respect for personal dietary committees or solidarity may run afoul of a philosophy of risk that emphasizes classic hazards to health and physical safety. All told, it begins to look less and less like food choice can be confined to the prudential realm” (p. 29) [1].

In this passage, Thompson emphasizes that people may no longer be able to use good reason and judgment when choosing their food. The foods you choose to eat not only affect your body and health, but it also affects people and ideas around you. There is potentially harm being done on third parties connected to certain food purchases.

Thompson’s take on this statement is just one of the many issues he delves into in From Field to Fork. He offers deep philosophical and ethical analyses while integrating economics, history, science, psychology, and politics. For example, when discussing food systems, Thompson addresses multiple factors to consider when ensuring food sufficiency. Environmentally, a growth in monoculture production systems to mass-produce certain crops can tax natural resources. Socially, these industrial systems can destroy healthy rural communities. Politically, there are injustices that make it difficult to distribute these resources fairly. An extensive framework is given regarding how to approach food sufficiency and other issues in the book.

As a philosopher and current W. K. Kellogg Chair in Agricultural, Food and Community Ethics, Paul B. Thompson provides a comprehensive guide to food ethics in his book. From Field to Fork: Food Ethics for Everyone will not only give you a deeper insight into food, but also into our society.

References Cited:

  1. Thompson, P.B. (2015). From Field to Fork: Food Ethics for Everyone. New York, NY: Oxford University Press.

 


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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The International Year of Pulses

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Photo credits: (flickr/Jessica Spengler)

The 68th United Nations General Assembly has declared 2016 the International Year of Pulses. [1] Pulses – that throbbing sensation of your carotid artery after a workout or during a first date, right? Nope. The UN suggests we celebrate the pulses that are leguminous crops harvested solely for their dry seeds. All lentils, and all varieties of dried beans, such as kidney beans, lima beans, butter beans and broad beans are pulses, as are chick peas, cowpeas, black-eyed peas and pigeon peas. Seeds that are harvested green, like green peas or green beans are classified as vegetable crops, not pulses. Legumes used primarily for oil extraction, like soybeans, are also not pulses. [2]

Why are pulses getting a year-long, world-wide campaign?

A global push for pulse production would address many problems of our global food system. The Food and Agriculture Organization of the United Nations’s campaign highlights these key benefits to pulse cultivation [1]:

  • Pulses are highly nutritious – they are excellent plant source of protein, and contain the B vitamins that our bodies require to convert food to energy
  • Pulses are economically accessible and contribute to food security at all levels – from farmers to consumers
  • Pulses foster sustainable agriculture, thus addressing agriculture’s role in climate change
  • Pulses promote biodiversity in agriculture

 

Now that we know the basics of pulses and why they’re important, let’s get scientific.

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Photo credits: (flickr/Kelly Garbato)

Pulses in the nitrogen cycle

Pulses are legumes, or plants in the family Leguminosae. Thanks to their symbiosis with many members of the diazotrophic, or nitrogen-fixing bacterial genus Rhizobium that live in their roots and feed them with nitrogen from the air, pulses have a particularly high protein content compared to non-legumes. [3] Within the bacterium, atmospheric nitrogen (N2), which is typically unusable to plants, is converted to ammonium (NH4+) via the activity of the enzyme nitrogenase. The nitrogen of ammonium is converted to other more complex compounds that are beneficial to humans, like amino acids – the building blocks of protein. In exchange for fixing nitrogen, the bacterium receives food from the plant — carbon in the form of glucose (C6H12O6).

 

This remarkable bacterial symbiosis also enriches the soil in which pulses grow with nitrogen compounds like nitrite (NO2) and nitrate (NO3), which is the preferred nitrogen source for other green plants. For this reason, farmers who crop-rotate with legumes don’t need to apply nearly as much fertilizer as farmers who don’t. [3]

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Pulses in a changing climate

Many pulses are also hardy and drought tolerant crops – lentils, broad beans, peas, and chick peas are all native to the Fertile Crescent of the Near East, and have adapted to sprout quickly and reproduce in the rainy season before the hot, dry summer [3].

Anatomy of the pulse

All food seeds consist of three basic parts: an outer protective coat, the small embryonic portion that develops into the mature plant, and the storage tissue that feeds the plant embryo. [3]The bulk of the seed consists of storage cells are filled with particles of concentrated protein and granules of starch, or organized masses of starch chains.

Cooking and starch retrogradation

When we cook pulses, hot water permeates the starch granules. As the water molecules work themselves between the starch chains, the granules swell and soften. When the pulses later cool down, the starch chains bond to each other again in tighter, more organized associations, resulting in firmer granules. (This process is called retrogradation.) [3] Consider leftover lentils or beans: they’re always harder and drier the next day, and they never get quite as soft as when they were first cooked. This is because during the process of retrogradation, some starch molecules form granules that are even more tightly associated than the bonds in the original starch granule. They form small crystalline regions that resist breaking even at boiling temperatures. [3]

Retrogradation of starch might foil your plans for leftover lentils, but it does do our bodies good: Our digestive enzymes cannot easily digest retrograded starch, so eating it results in a more gradual rise in blood sugar compared to the effects of non-retrograded starch. [3] Our intestines need help breaking down this tough starch, and the beneficial bacteria in our large intestines are happy to be of assistance. Just as the diazotrophic bacteria in soil work in harmony with leguminous plants, our intestinal bacteria digests what we cannot. Thus the retrograded starch functions as a prebiotics, or food for the probiotic bacteria in our guts. Well-fed gut bacteria make for healthy digestive tracks and happy bowels.

Will this pulse promotion save the world and fix the global food economy? Perhaps. We can all do our part by making a hearty spinach dal for dinner tonight, and sweet red bean paste for dessert.

 

Works Cited

  1. “”Save and Grow in Practice” Highlights Importance of Pulses in Crop Rotations and Intercropping.” Pulses – 2016 | 2016 International Year of Pulses. Food and Agriculture Organization of the United Nations, n.d. Web. 05 Feb. 2016.
  2. “What Are Pulses? | FAO.” What Are Pulses? | FAO. Food and Agriculture Organization of the United Nations, 15 Oct. 2015. Web. 05 Feb. 2016.
  3. McGee, Harold. “Seeds.” On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004. N. pag. Print.

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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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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Deep-fried Turkey: Delicious or Dangerous?

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Is a Deep-Fried Turkey your Destiny [Photo Credit: Jinx!]

While you may think the most dangerous thing you can do during the holidays is talk politics with your uncle, starting a kitchen fire is a more realistic threat to your safety. According to the United States Fire Administration (USFA), the number of structure fires double on Thanksgiving, causing on average $28 million in property damage1. Cooking causes the majority of these blazes, with grease and oil as the main culprits in ignition2. Despite the astonishingly large number of holiday mishaps, home cooks continue using fats. A select few even engage in one of the most daring of food adventures: deep-frying a turkey.

A quick Internet search for “deep-fried turkey” reveals how dangerous this culinary practice can be. There are plenty of videos and pictures that document the aftermath of a deep-fried turkey fire. A careless and unprepared chef can turn a deep-fried turkey into a deep-fried disaster within minutes. The bird quickly becomes engulfed in a fireball that can be seen from the rest of the neighborhood. So then, what makes deep-frying more appealing than roasting? More importantly, can it be done safely?

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[Photo credit: State Farm]

The key to effectively deep-frying a turkey is oil. Oil makes the bird both delicious and dangerous. Oil’s interaction with the poultry causes the characteristic crispy golden brown crust that draws people to deep-frying. This same oil, however, can ignite and cause a fire. To effectively and safely deep-fry a turkey, you must understand the science underlying deep-frying.

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Oil is the key to a Deep-Fried Turkey [photo credit: Joe]

The main appeal of a deep-fried turkey is the texture created by oil interacting with the bird’s skin. In deep-frying, hot oil completely engulfs the food. Put an uncooked turkey in hot oil and bubbles immediately start forming. The bubbles are not from the oil, but from the water within the surface of the bird that escapes as tiny pockets of steam. Water boils at 212 °F, but the temperature of oil in a deep fryer is typically around 350 °F or greater. Because of these high temperatures, the water in the turkey skin rapidly evaporates. This dehydration at the surface combined with the high temperature make conditions perfect for the Maillard reaction.

Maillard reactions create the characteristic deep browning and appealing aromas that you may have experienced when you deep-fry a turkey. These reactions typically occur when proteins and sugars in foods are exposed to high heat (284 – 329 °F): the amino acid building blocks of proteins react with sugars at high heat to create a complex set of flavor molecules. This is why a deep-fried turkey may evoke similar flavors and aromas as seared steak, roasted coffee, or toasted bread. As heat continues to vaporize the water on the bird’s skin, the reaction speeds up and the resulting flavor molecules become more and more concentrated.

While Maillard reactions can also be achieved through roasting a turkey, deep-frying avoids some of the pitfalls of oven roasting. First, because the hot oil completely envelops the bird, the outside gets an even brown coat. The temperature of the oil remains relatively constant as it spreads into every crevice. Such uniformity can be harder to achieve in traditional oven roasting, because of differences in air temperature within the oven. Moreover, poor heat circulation can result in uneven cooking. In extreme cases, you might find one side of the turkey charred, while the other is still undercooked.

Next, because the oil can transfer more heat than air per unit volume and time, deep-frying can allow the bird’s surface to get hot quickly enough so that the inside does not overcook. In deep-frying, oil acts as the workhorse transferring heat to food. By contrast, ovens rely on air to transfer heat. Compared to air, cooking oil has a much higher rate of heat conduction. Heat transfers between substances when the molecules collide and transfer energy. Because a liquid such as oil is more dense then air, its molecules are more closely packed; there are more molecules per volume to transfer energy. As a result, the high heat needed for the Maillard reactions develops much faster in a deep fryer than in the oven. In general, oven roasting generally takes about 2-4 hours, while deep-frying can take as little as 30 minutes. Slower increases in surface temperature, as in the case of the oven, allow for more time for the high heat to spread to the center of the turkey and overcook the inside.

Many deep-frying fans claim that the practice “seals in the juices”, however, internal temperature has a larger impact on moisture. If you’ve ever bit into a dry piece of fried chicken, you know, that deep-frying does not guarantee juicy poultry. Fans claim that oil creates a barrier to lock in moisture, but as previously highlighted, hot oil causes it to vaporize and escape. Even water near the interior can escape if it reaches the boiling point because the crust remains porous. The meat on the inside cooks in the same way as in roasting, but only faster because the oil transfers more heat. Thus, regardless of whether you deep-fry or roast the bird, you need to watch the internal temperature to get a juicy turkey.

While hot oil is essential for transforming your turkey into a delicious brown and crispy treat, properly controlling the oil will keep you safe. The first step is having the proper equipment. While a turkey can be deep fried in any number of large pots you already have, none of them are specifically designed to safely handle 3 gallons or more of hot oil and a giant turkey. Having a deep fryer specific for turkeys ensures that when you use the right amount of oil, the turkey is completely submerged and the oil won’t overflow. Also you can cook with a turkey deep fryer outside; this keeps the hot oil safely away from anything flammable in your home. So if you do make a mistake, it’s far away from anything that can spread a fire.

Next, to avoid turning the turkey into a giant fireball, it must be properly dried. This means checking that the bird is completely thawed and free of excess water. If too much ice or water remain, either can quickly vaporize causing oil to spray into the air. You may have seen a similar reaction occur when you throw drops of water into hot oil to test if it’s reached frying temperature. Sudden vaporization results in tiny droplets of oil spewing out in a fine mist. As microscopic droplets, the oil increases its chances of contacting the burner and reaching its flash point, or the temperature at which a material can ignite. (The flash point is around 600-700°F for many cooking oils.) In the deep fryer, oil won’t get as hot, but as droplets, oil can reach this temperature because of their small size and increased surface area. The ignition of a few small oil droplets can set off a chain reaction that engulfs the entire bird. This is why a seemingly innocent icy turkey can turn into a fireball.

Finally, you may want to consider that deep-frying adds a significant amount of fat to your bird compared to roasting it. The entire surface of the turkey is covered in oil and some may seep into the interior. In general, deep-frying can result in as much as 5 to 40% of a food’s weight in oil3. If you are concerned about your fat intake you might want to avoid this deep-fried treat. However, eating a deep-fried bird only on Thanksgiving likely won’t jeopardize your health too much.

Deep-frying a turkey requires significant culinary effort. Although this cooking method is potentially dangerous, your fowl can develop delicious flavors and aromas that cannot be achieved as quickly in the oven. Whether or not you want to make the investment ultimately depends on what you like about eating turkey. If you only care about juicy meat, then using an oven and monitoring the temperature can be easier. However, if you crave a truly unique treat encased in a crispy brown crust, then deep-frying a turkey may be your next gastronomic adventure.

References cited

    1. USFA. Thanksgiving Day Fires in Residential Buildings (2009-2011) http://www.usfa.fema.gov/downloads/pdf/statistics/snapshot_thanksgiving.pdf
    2. USFA. Cooking Fires in Residential Buildings (2008-2010) http://www.usfa.fema.gov/downloads/pdf/statistics/v13i12.pdf
    3. Owen R. Fennema, editor, Food Chemistry, 2nd Edition (New York: Marcel Dekker, Inc, 1985), 210-221

Vince ReyesAbout the author: Vince Reyes earned his Ph.D. in Civil Engineering at UCLA. Vince loves to explore the deliciousness of all things edible.

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Chocolate’s Future & Mysteries

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In the town of Reading, located in Berkshire, England, exists the International Cocoa Quarantine Centre, where tropical cacao plants are kept to prevent the spread of pests and diseases which threaten the world’s chocolate supply. Over at Technische Universität München, physicists have shown that molecular simulations can solve how the chocolate-making process turns bitter cacao to sweet, silky chocolate on a molecular level.
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Structural Changes in Chocolate Blooming

Is there anything more disappointing than finding a chocolate bar in the back of the desk drawer, anticipating a tasty treat, then unwrapping the bar only to find a dull, grey haze has overtaken your dear candy? Seeing as bloomed chocolate is still edible, yes, there are many things more disappointing than that. But surely you’re curious about how chocolate that was once shiny and perfect came to be filmy and rough. Chocolate blooming, the process that produces the white-grey film that appears on the surface of an old chocolate, is due to molecular migration. More specifically, this imperfection is caused by the movement of fats to the surface of the chocolate followed by a subsequent recrystallization. In a paper published by Applied Materials & Interfaces, a team of researchers dedicated to keeping our chocolates blemish-free has clarified the precise mechanisms that cause chocolate blooming.

The main fat in chocolate is cocoa butter, which is solid at room temperature and melts at 37 degrees Celsius. The proportion of solid to liquid cocoa butter depends on the lipid composition, which depends on which specific triglycerides are present. The solid to liquid proportion also varies with the storage conditions of the chocolate.

As proposed by Aguilera et al, scientists who study this chocolate blooming, consider chocolate as a particulate medium of fat-coated particles such as cocoa solids, sucrose, and milk powder, all suspended in a fat phase with the aid of an emulsifier, which helps to mix fats and oils with water, which usually repel each other. There are six crystallographic polymorphs of cocoa butter molecules, that is, there are six ways the molecules can organize themselves. The structural stability of these polymorphs increases from 1- 6; form 1 is the best at forming solid butter at room temperature, while form 6 tends to arrange in the loose bonds of a liquid. Form 5 is the main form in chocolate, as it possesses the most aesthetically desirable properties. While the phenomenon of blooming is well known to result from melting and recrystallization of chocolate into a less desirable polymorph, it has been unclear how fat moves through the chocolate particle network: Does it move along the fat-particle interface? Does it diffuse through the fat phase (cocoa butter), or through the matrix of assorted particles?

Possible lipid migration pathways in chocolate - Reinke et al

Possible lipid migration pathways in chocolate – Reinke et al

In this experiment, researchers used synchrotron microfocus small-angle X-ray scattering to determine the preferential migration pathway of the cocoa butter molecules surrounded by three different soild components (cocoa solids, skim milk, and sucrose). This technique allows researchers to record the scattering of x-rays through a sample with defects in the nanometer range. They can then extrapolate information about the material’s macromolecules, their shapes and sizes up to 125 nanometers, and distances between partially ordered materials, such as pore sizes. For this experiment, this method is better than more traditional macroscopic techniques as the sample does not need to be dissected in order to examine it, therefore the same sample can be continually analyzed.

Sketch of the experimental setup - Reink et al

Sketch of the experimental setup – Reink et al

The researchers prepared and tempered four different chocolate samples. An initial scattering of x-rays and data collection was performed before the addition of sunflower oil, then 10 uL of oil was pipetted onto the chocolate surface, and a second scan was performed. Images of the droplet were captured through a high-speed camera. These scans were repeated at 5, 10, and 30 minutes after oil addition, and again after 1, 2, 5, and 24 hours.

The results obtained suggest that oil is migrating through pores and cracks in the solid structure driven by capillarity within seconds. This means that the oil can flow in narrow spaces in opposition to gravity. Then chemical migration through the fat phase occurs. The oil doesn’t traverse the fat-particle interface, nor does it move through the matrix of solid particles. This migration disrupts the crystalline cocoa butter, which induces softening.

Because the most immediate migration of oils occurs through the material porous structure, the formation of chocolate bloom could be prevented by minimizing pores and defects in the chocolate matrix. To prevent the longer-term effects of chemical migration of lipids, one must minimize the content of non-crystallized liquid cocoa butter. Tempering chocolate lends to crystalline structures that resist migration, as will reducing the liquid fat content. However, to ensure that you never encounter a sad hazy chocolate again, we recommend eating all chocolate goods expeditiously.

Works Cited

  1. Tracking Structural Changes in Lipid-based Multicomponent Food Materials due to Oil Migration by Microfocus Small-Angle X-ray Scattering. Svenja K. Reinke, Stephan V. Roth, Gonzalo Santoro, Josélio Vieira, Stefan Heinrich, and Stefan Palzer. ACS Applied Materials & Interfaces 2015 7 (18), 9929-9936. DOI:10.1021/acsami.5b02092
  2. Aguilera, J. M.; Michel, M.; Mayor, G.Fat Migration in Chocolate: Diffusion or Capillary Flow in a Particulate Solid?—A Hypothesis PaperJ. Food Sci. 2004, 69, 167–174

 


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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Freezer Burnt Meat

Photo credit: flickr/Steven Depolo

Photo credit: flickr/Steven Depolo

Freezing is an indispensable tool in modern cooking and eating. The biochemical processes that typically occur in meats cause decay, fat oxidation, and rancidity; the higher the temperature, the faster these reactions occur. Thus, we can largely thwart off these undesirable processes by keeping meat chilled. But tossing meat into the freezer rarely results in rainbows, sunshine, or perfect burger patties, because strangely enough we can also accelerate meat decay with cold. Freezer burn can take a beautiful filet mignon and turn its surface into a leathered, unappetizing slab.

Freezer burn is caused by water sublimation from ice crystals at the meat’s surface into the dry freezer air. Sublimation occurs when a solid substance undergoes a phase change and becomes a vapor without first passing through the liquid phase. The ice crystals on the meat surface sublimate, and leave behind tiny cavities. These tiny yet numerous cavities increase the surface area of the meat and expose more tissue to the air. This accelerates oxidation of fats, which causes the rancid flavors of old spoiled meat. We usually describe oxidized fats as simply tasting “off,” which is a vague term but seems apt if you’ve ever tasted lipids past their prime, perhaps by using shortening that has been in the pantry since you were a toddler.

Photo Credit: flickr/Marcus Ward

Here, solid ice crystals directly vaporize without first passing through the liquid phase. Photo Credit: flickr/Marcus Ward

In addition to the surface area increase caused by sublimation, the freezing process itself lends itself to fat oxidation. When the liquid water in meats crystallize in the cold, the concentrations of oxidizing salts and trace metals in the tissues increases. Unfortunately, oxidation can occur over time even in wrapped and frozen meats. Some oxygen will inevitably remain in contact with the meat, unless we create a vacuum seal.

Once meat has been damaged by the cold, there’s no undoing the oxidation. So either we plan our meals so that meats are cooked immediately after purchase, or we learn to prevent the sublimation that ruins both our pork chops and our days. We simply need to keep water crystals inside the meat and keep oxygen out. Using a vacuum sealer is our best bet for avoiding freezer burn, but for cheapskates like me who won’t shell out the $30 for the sealing device, a water-impermeable plastic wrapped tightly around the meat works well enough for most home chefs.

Thus meat is sealed away happily in plastic, free from villainous oxygen. Photo credits: flickr/Mike

Thus meat is sealed away happily in plastic, free from villainous oxygen. Photo credits: flickr/Mike

References cited

  1. McGee, Harold. “Meats.” McGee on Food & Cooking: An Encyclopedia of Kitchen Science, History and Culture. London: Hodder & Stoughton, 2004. N. pag. Print.
  2. “Sublimation.” The Columbia Electronic Encyclopedia. Columbia University Press, 2012. Web. 20 July 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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Bar Stools and Molecules: Buttery Nipple Science

[Photo Credit: Vince C Reyes]

[Photo Credit: Vince C Reyes]

You may think a buttery nipple is just a fun shot to buy a friend on his or her birthday, but it’s more complex than that. It’s got layers… specifically two. For those not familiar with the bar classic, the buttery nipple is composed of a layer of Irish cream sitting on top of butterscotch schnapps.

Buttery Nipple Shot Recipe

½ oz. Irish cream
1 oz. Butterscotch schnapps

  1. Pour 1 oz. of Butterscotch schnapps into a chilled shot glass.
  2. Carefully pour ½ oz. of Irish cream onto the back of a downturned spoon so it rolls from the spoon and floats on the surface of the schnapps.
  3. Enjoy!

This and other layered shots like the American flag, the B-52, and the Alien Brain Hemorrhage, take advantage of the slight differences in density among spirits. As density, a substance’s mass per unit volume (Density = mass / volume), dictates the layering in these drinks; the most dense liquid is placed at the bottom followed by progressively less dense liquids. In the case of the buttery nipple, the less dense Irish cream floats on the more dense butterscotch schnapps. If you were to reverse the order with the butterscotch schnapps poured on the Irish cream, the layers would not form. The more dense butterscotch schnapps would sink to the bottom of the glass and result in a mixture of the two spirits.

For the home bartender looking to make new layered drinks, the absolute density of a spirit is not always easy to measure. However, a different quantity, specific gravity, is often available online1. Specific gravity is the ratio of the density of substance to water (specific gravity = density of a substance / density of water). Water has a specific gravity of 1.0. More dense liquids have specific gravities greater than 1.0 and less dense liquids have specific gravities less than 1.0. In the case of the buttery nipple shot, butterscotch schnapps (Dekyper’s ButterShots) has a specific gravity of 1.12 while Irish cream (Bailey’s) has a specific gravity of 1.06.1 The specific gravity is often available online for alcoholic beverages because it is important in the fermentation and distillation process, and different beers, wines, and spirits have characteristic specific gravities.

If the specific gravity of an alcoholic beverage cannot be found, some recommend using proof or alcohol by volume (ABV) to layer drinks. Both are mandated on all alcoholic beverages sold and therefore easy to find. In general, proof is the amount of alcohol in a beverage. Specifically in the US, proof is defined as twice the percentage of the alcohol by volume. The alcohol in any beverage you drink is ethyl alcohol, also called ethanol (C2H6O).

Figure 1: Molecular Formula of Ethanol [Image Credit: Vince C Reyes]

Figure 1: Molecular Formula of Ethanol [Image Credit: Vince C Reyes]

At room temperature (77°F or 25°C), ethanol has an absolute density of 789.00 kg/m3 and a specific gravity of 0.7872. As many alcoholic spirits are primarily a mixture of ethanol and water, which has an absolute density of 999.97 kg/m3 and specific gravity 1.0, greater alcohol content can often correspond to a smaller density. For example in the case of the buttery nipple, Irish cream (Baily’s) is 17% ABV, while Butterscotch schnapps is 14.8% ABV. Therefore, the higher alcohol content and corresponding lower density of the Baily’s Irish cream allows it to sit on top of butterscotch schnapps. This shortcut, however, is not always correct as many spirits have ingredients other than water and ethanol. Many spirits contain cream, sugars, or other flavoring agents, which can change their densities, making alcohol content an imperfect proxy for density. For example, Smirnoff’s flavored vodkas all have 35% ABV, but have varying specific gravities: citrus vodka has a specific gravity of 0.96, while the more dense watermelon vodka has a specific gravity of 0.981.

Figure 2: Layering in a Buttery Nipple.  *ABV is not always an indicator of density. [Image Credit: Vince C Reyes]

Figure 2: Layering in a Buttery Nipple.
*ABV is not always an indicator of density. [Image Credit: Vince C Reyes]

Lastly although other factors such as altitude affect density, temperature is the other most relevant factor for an aspiring bartender. Liquids are denser when cold. Temperature is an indicator of the speed of molecules within a substance. At low temperatures, liquids have slower moving molecules that pack closer together resulting in greater mass per volume. In contrast, at higher temperatures, molecules in liquids move around more quickly and take up less space resulting in a reduced density. For example, water near room temperature (70°F [21°C]) is less dense (0.998 g/cm3), than water near freezing (1.000 g/cm3 at 39.2 °F [4.0 °C])3. This is why using chilled spirits, glass wear, and spoons when making a layered shot can ensure that spirits remain at their densest and form layers.

Ultimately, a great layered shot is one that is not only effectively layered, but also delicious. If you don’t enjoy the buttery nipple, you now have the scientific knowledge to experiment with your own concoctions!

Learn more

  1. Specific Gravity of Different Spirits from GoodCocktails.com
  2. Specific Gravity of Other Liquids from Engineering Tool Box
  3. The Density of Water at Different Temperatures from the US Geological Survey

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.

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