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Aquafaba & Other Hopes for Delicious Egg-free Meringues

Photo credit: veganbaking.net (vegan-baking/Flickr)

Photo credit: veganbaking.net (vegan-baking/Flickr)

Meringues are one of the few desserts that are simple yet elegant works of art. They are also precursors to other impressive, albeit considerably more complicated, desserts such as baked Alaska, lemon meringue pies, and macarons. At the bare minimum, all you need to make a fluffy meringue is egg whites, sugar, and an electric mixer—or an egg beater and some arm power. For vegans, this egg-containing dessert is not an option—but why should vegans (and those with egg allergies) miss out on this sweet, airy dollop of heaven?

To make a decent egg-free meringue, it helps to understand the meringue at the molecular level. How does a liquid get whipped into a cloud-like solid?

Egg whites, comprising 90% water, are undeniably runny. The other 10% consists of proteins, which play a major role in the fluid-to-fluff transformation. Mechanical stress from rigorously beating the egg whites causes the egg white proteins to denature, unfold from their natural structure. This exposes various amino acids, the building blocks of proteins, to the rapidly aerating environment. Some of the amino acids are hydrophobic (water-fearing), and some are hydrophilic (water-loving). As the egg whites are whipped, hydrogen bonds form between the hydrophilic amino acids and water in the egg whites. The hydrophobic amino acids prefer to be exposed to the air that is quickly beaten into the liquid mixture. Air ends up trapped in the meshwork of denatured proteins within the developing foam, and so the longer the mixture is beaten, the fluffier it gets. To retain the trapped air bubbles and generate peaks that stand up straight, sugar is added as a stabilizer. And eccola! Una nuvola dolce nella ciotola; a fluffy meringue is ready to bake or prepare into macarons or boccone dolce.

To create an equally amazing and delicious vegan counterpart, the egg whites would have to be substituted with an ingredient that has both water-loving and water-fearing parts. Logic may think to search for a plant-based protein alternative, but French chef Joël Roessel discovered that chickpea brine works perfectly well as a vegan egg-white substitute [1]. Coined aquafaba by Goose Wohlt (Latin for “bean water”), the leftover water from a can of chickpeas can be combined with sugar and whisked into a vegan meringue that surprisingly tastes nothing like beans. Of all the possible substitutions, why does aquafaba work in lieu of egg whites?

Photo credit: getselfsufficient/Flickr

Water leftover from cooking chickpeas, also known as aquafaba, can be used in lieu of egg whites. Photo credit: getselfsufficient/Flickr

Anne Rieder, a scientist at the Norwegian food research institute Nofima, analyzed aquafaba and revealed that the bean water contains equal amounts of proteins and carbohydrates [2]. The function of proteins in the aquafaba are similar for meringue-making; Rieber suggests that the carbohydrates may serve as an additional stabilizer by increasing the viscosity of the water portion of the foam.

To create foams like meringues, Kent Kirshenbaum, a professor at NYU, was inspired by chemistry to invent a foaming agent that is rich in saponins, currently awaiting patent approval. Saponins are a class of chemicals found in plants, including beans like chickpeas. The name derives from the soapwort plant, Saponaria, which contains the Latin root for soap, sapo; this is a fitting name, given the compound’s propensity to foam when shaken in water [3]. Like the amino acids of proteins, saponin molecules contain a hydrophobic and a hydrophilic moiety that enables them to interact with both air and water.

Whatever the reason for avoiding eggs, at least you won’t have to forfeit the heavenly delight that is a lightweight meringue cookie.

References cited

  1. Aquafaba history.” The Official Aquafaba Website.
  2. Aquafaba, what is its chemical composition?Frie kaker.
  3. Saponins.” Cornell University Department of Animal Sciences.

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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Kent Kirshenbaum

Dr. Kent Kirshenbaum received his PhD in Pharmaceutical Chemistry at UCSF, is an NSF Career Award recipient, and is currently a professor of Chemistry at NYU. His research focuses on the creation of new peptide-based macromolecules that can be used as research tools or therapeutic strategies. In 2012, he filed a patent for a foaming agent which acts as a vegan substitute for egg whites, making vegan meringues a delicious possibility.

See Kent Kirshenbaum March 8, 2016 at “The Impact of What We Eat: From Science & Technology, To Eating Local”

Kent Kirshenbaum

What hooked you on cooking?
Spending time with my mom got me hooked on cooking. She exemplified the “slow food” concept, and she’d take days to make a pasta sauce. I grew up in a drafty house in San Francisco that was cold all year around, and being near her at the stove was the warmest place to be. Once my wife and I had kids, I realized how satisfying it was for me to provide my family with sustenance through cooking and culture through cuisine.
My dad got me hooked on science. He studied metallurgy and worked for a mining company. He would go on business trips and bring me back samples of different minerals to play with. It was kind of like the situation described in the book “Uncle Tungsten” by Oliver Sachs.
The coolest example of science in your food?
Mayonnaise. You take two immiscible liquids – oil and water, and find a way to get them to mix. How do they do that?? Add an emulsifier, provide some energy and voila! It’s just a shame the product itself is so repugnant.
The food you find most fascinating?
Fermented butters. Such as smen, the fermented butter of North Africa and “bog butter” from the British Isles.
What scientific concept–food related or otherwise–do you find most fascinating?
I’m fascinated by the relationship between the sequence, structure and function of proteins.
In the kitchen, transglutaminase — also known as meat glue — is a compelling example of enzymology. Nixtamilization is an amazing concept, and the word “nixtamilization” itself is like a really short poem.
Your best example of a food that is better because of science?
Either Pop Rocks or the clean water that comes out of my home faucet. Although I’m not sure either of them really qualify as a foodstuff.
We love comparing the gluten in bread to a network of springs. Are there any analogies you like to use to explain difficult or counter-intuitive food science concepts?
When explaining specificity in the sensory perception of food, I use the “lock in key” analogy to describe how ligands engage protein receptors. Although the analogy is imperfect, it begins to get the idea across.
How does your scientific knowledge or training impact the way you cook? Do you conduct science experiments in the kitchen?
Because I am trained as a chemist, I am fastidious about following a published protocol (recipe) and I tend to be absurdly precise about volumes. I love experimenting with food – we filed a patent application on new way to make vegan meringues. But when it comes to cooking at home I tend to be a traditionalist.
One kitchen tool you could not live without?
My home water carbonation system. I love sparkling water that I can generate from the New York City public water supply and doesn’t need to be shipped from a European spring.
Five things most likely to be found in your fridge?
Harissa, capers, preserved sour cherries, home-made stock and parmesan cheese. I get anxious if my supply of Reggiano is running low.
Your all-time favorite ingredient? Favorite cookbook?
I’m a spice guy. Right now I’m fixated on sumac and cardamom. My favorite cookbooks is “Where Flavor Was Born” by Andreas Viestad which explores how spices are used across the region of the Indian Ocean. It inspired me to visit a cardamom plantation in Kerala, India.
Other favorites include “In Nonna’s Kitchen” and “Cucina Ebraica”, because these books connect me to the memories of my mother and her mother.
Your standard breakfast?
A cup of black coffee and a baked good that I enjoy on my walk from home to my lab. New Yorkers have a bad habit of walking and eating. On the weekends, bagels and smoked salmon. No doughnuts. Never a doughnut. Maybe a beignet. But only in New Orleans.

The Keys to Cheese: Does This Cheese Melt?

Melted Cheese [Photo Credit: Pittaya Sroilong]

Melted Cheese Frize [Photo Credit: Pittaya Sroilong]

Whether you are making cheese fries, grilled cheese sandwiches, quesadillas, baked cheese bites, or homemade mac and cheese, choosing the right type of cheese can make or break these comfort foods. The key to all of these dishes is cheese that produces an even and homogenous melt. Cheeses like Cheddar, Mozzarella, and Gruyere are used often. If you aren’t feeling adventurous, you could just memorize the names of these greatest hits. However, if you want to experiment and change the melty cheese game, you’re going to have to understand why these cheeses work.

Let’s first examine what happens to cheese as it melts. The interactions of casein (milk proteins) and calcium help define its solid structure. When solid, caseins are bound together in large branching porous protein networks that entrap milkfat and water. Calcium (as calcium phosphate) acts as a bridge to stabilize these networks. When you apply heat to a cheese, melting occurs in two stages. First, at around 90 ˚F, milkfat is released1. This is because hydrophobic (water-repulsive) interactions between casein molecules increase under heat2. These interactions force out water molecules and the space between casein molecules increases allowing milkfat, which melts at this temperature, to escape. If you’ve put cheese on a burger that’s being grilled, you may see little sweat beads of liquid form on the cheese in the early stages of melting. The second stage happens at about 40 to 90 degrees higher, at around 130 – 180˚F3. At this point, the casein proteins do not break down, but rather, the increased movement of the proteins, resulting from the heat, allows for the proteins to act more fluid-like and the cheese melts.

There are many factors that control melting and explain why melting temperatures vary by as much as 50 degrees. No one factor defines a cheese’s melting properties as these factors can interact.

Moisture and Fat

Cheese with higher moisture and fat content tends to have lower melting points. For example, high moisture cheeses like Mozzarella melt around 130 ˚F and low moisture cheeses like Swiss melt at 150 ˚F 2. First, as previously highlighted, the milkfat and water portion of the cheese react to heat at lower temperatures than the proteins. Accordingly, with more moisture and fat present in a cheese, greater proportions of the cheese are susceptible to melting at lower temperatures. When the fat becomes liquid, it can no long provide support for the protein networks. Secondly, increased moisture and fat means that the casein proteins are more spread out and the mesh size (gap between proteins) is larger. This means there are fewer connections (bound calcium bridges) between proteins networks making melting more likely to occur at lower temperatures.

You may not know the exact moisture and fat content of every cheese variety without looking at a label, but intuitively, softer cheeses have more moisture and fat. Additionally, younger cheeses generally have more moisture so they also tend to melt more uniformly and evenly.

Acid Content

Chesses typically melt homogenously and evenly around a pH of 5.0 – 5.44. This is related to the calcium bridges. At too high a pH (pH > 6), too much calcium is present as bound calcium phosphate and the protein is too tightly bound to melt. With lowered pH, the calcium phosphate bound to the casein is replaced by hydrogen (H+), allowing for more movement among proteins.2 At around a pH of 5.0 – 5.4, there is a sufficient number of calcium present as bridges to allow for melting. At too low a pH (pH < 4.6), too many calcium bridges are lost and proteins aggregate and are unable to flow and melt evenly.

Lastly as a caveat, the factors being highlighted are specific to rennet-set cheeses, and not acid-set cheeses. Acid-set cheeses like queso fresco, paneer, and ricotta are not generally used, as they don’t produce even melts4. This results from the way they were made. In cheese making, you have two options for separating the solid curds (primarily casein proteins) and the liquid whey; Use rennet (an enzyme derived from the intestines or baby goats and cows) or use an acid (like vinegar or lemon juice).

When they are free floating in liquid milk, casein proteins have a slightly different molecular structure than when they are in cheese. In milk, caseins stick together in small clusters (micelles) that have negative charges on their surface. Since negative charges repel each other, these micelles won’t combine. Adding acid to heated milk lowers the pH, which neutralizes the negative charges on the micelles; therefore the casein micelles can aggregate. In contrast, using rennet to set cheese is a more targeted approach. In this process, an enzyme contained in rennet called chymosin, selectively removes negatively charged portions of the casein micelles and allows the micelles to clump.

In an acid-set cheese, calcium bridges are never formed as a result of the acidic environment used to generate the cheese5. These cheeses are only held together in protein aggregates rather than protein networks with calcium bridges and don’t produce the even melt desired.

Bottom Line:

Rennet-set cheeses with high moisture and fat are the best cheeses for melting as they melt evenly and consistently.

But don’t fret if you still want to harness the flavor of other cheeses (especially older or drier cheeses)! You have options: Try using a cheese blend with a higher proportion of the better melting cheeses and a small proportion of the other cheeses. For example, this recipe uses a 1:4 ratio. Experiment! You now know the keys for melty cheese!

References cited

  1. Schloss, Andrew and David Joachim. “The Science of Melting Cheese” http://www.finecooking.com/item/64019/the-science-of-melting-cheese
  2. Johnson, Mark. “The Melt and Stretch of Cheese” https://www.cdr.wisc.edu/sites/default/files/pipelines/2000/pipeline_2000_vol12_01.pdf
  3. Mcgee, Harold. On Food and Cooking. 2004 “Cheese” (57 – 67).
  4. Tunick, Michael. The Science of Cheese. 2013 “Stretched Curd Cheeses, Alcohols, and Melting” (82 – 91).
  5. Sargento Food Service. “Cheese Melt Meter” http://www.sargentofoodservice.com/trends-innovation/cheese-melt-meter/
  6. Achitoff-Grey, Niki. “The Science of Melting Cheese” http://www.seriouseats.com/2015/08/the-science-of-melting-cheese.html

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

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The Science of Steamed Milk: Understanding Your Latte Art

Guest post by Christina Jayson

Photo credit: Dan Lacher (journeyscoffee/Flickr)

Photo credit: Dan Lacher (journeyscoffee/Flickr)

Watch a barista at work and you will observe the art of preparing a perfect café au lait, cappuccino, macchiato, or mocha – all of which involve different quantities of steamed milk. Behind the artistic foam hearts and milk mustaches lies a science to steamed milk.

Students of UCLA’s SPINLab (Simulated Planetary Interiors Lab) team developed an app that allows you to “calculate the power output of your steamer” and predict the “steaming time for optimal milk temperature based on amount, type and starting temperature of your milk”. Samuel May of SPINlab explains the calculations the app takes into account that allows it to predict the temperature of milk at a given time. They show that the temperature increase of milk over time is linear, allowing them to make these predictions based on a Linear Heating Model.

But what exactly happens when you steam milk? Steaming involves introducing hot water vapor (T = 250-255 °F) into cold milk (T = 40 °F) until it reaches the ideal temperature for a “perfectly steamed latte.”

While the process sounds simple enough there are a host of variables that need to be considered. Most importantly, different milks require different amounts of steaming time. As SPINLab expert, Sam warned, too high a temperature can scald the milk: scalding kills bacteria and denatures enzymes; this inactivates the enzymes and causes curdling as denatured milk proteins clump together.  Since different types of milk and dairy alternatives have different molecular compositions, this means they have different steaming temperatures. This difference all boils down to the composition of milk.

CJ_steamed milk_2

Figure 1. Milk broken down into its molecular constituents. Modified from Properties of Milk and Its Components. [3]

Milk is composed of three main components: of proteins, carbohydrates, and fat (Figure 1).

Milk is 3.3% total protein, including all nine essential amino acids; the protein content can be broken down into two main types, casein and serum. Serum, or whey proteins, contain the majority of the essential amino acids. Whey proteins can be coagulated by heat and denaturation of some of these proteins with heat; this gives cooked milk a distinct flavor. Caseins form spherical micelles that are dispersed in the water phase of milk [1]. When steaming milk, the injected air bubbles disrupt the micelles. The protein molecules then encompass the air bubbles, protecting them from bursting and leading to the formation of foam. The take away: The different protein content of different milks consequently affects each milk’s ability to maintain that frothy foam decorating your latte [2]. Whole milk results in a thicker, creamier foam and skim milk results in more foam and larger air bubbles, while almond milk is able to hold a light and long-lasting foam [2].

Table 1: Percent of protein in different types of milk and non-dairy alternative [2]

Milk % Protein
Skim milk 3.4
1% milk 3.4
2% milk 3.3
Whole milk 3.2
Soy milk 2.7
Almond milk 0.4

Lactose is the carbohydrate component of milk – a disaccharide composed of D-glucose and D-galactose. There are two forms of lactose present in an equilibrium mixture due to mutarotation, α-lactose and β-lactose. β-lactose is the more stable form, and also the sweeter form of the two [3]. When you steam milk past a temperature of 100 °C, this causes a “browning reaction,” or the Maillard reaction, in which the lactose and milk proteins – mostly caseins – react to form what is know as an Amadori product [4]. The colorless Amadori product is a molecular complex between the lysine residues of protein molecules and the lactose molecules. As the reaction continues with heating, the Amadori product can undergo dehydration and oxidation reactions, or rearrangements that lead to a loss of nutritional value and the formation of unappealing flavor compounds in milk that Sam warned could result from over-steaming.

The last main constituent of milk is the milkfat that exists as globules in the milk. Over 98% of milkfat is made up of fatty acids of different types, including saturated, monounsaturated, and polyunsaturated fatty acids. These fat molecules can also stabilize the formation of foam by surround the air and entrapping it in a bubble. While higher fat content leads to stable foam at temperatures below room temperature, milks with lower fat contents (like skim milk) are better at stabilizing foam at higher temperatures [3]. This could be due to the reduced surface tension of the fat along the air bubble surface that is a result of an increase in fat percentage. Heating up these fat molecules not only affects foam texture; when heated or steamed, the fatty acids also participate in chemical reactions, such as oxidation reactions, that can give rise to an undesirable flavor [5].

For the lactose intolerant and fans of non-dairy alternatives, you may be wondering how lactose free options such as soy or almond milk compare. Their steaming temperatures differ mildly due to their distinct properties – for example, almond milk has a lower protein content (Figure 2). According to the experience and experimentation of expert baristas, certain brands of soy or almond milk can hold a foam better than others; the science underlying this phenomenon still remains to be determined.

Table 2: Ideal steaming temperatures for milk and non-dairy alternatives [6]

Milk Soy Milk Almond Milk Coconut
150 °F 140 °F 130 °F 160 °F

The moral of the story is that each component of milk contributes to its ability to froth and foam, and steaming influences each of these components. With this knowledge, you can wisely choose your milk at Starbucks depending upon your foaming desires, or simply download Sam’s app and perfectly steam your milk at home.

References cited

  1. O’Mahony, F. Milk constituents. Rural dairy technology: Experiences in Ethiopia, Manual No.4; International Livestock Centre for Africa Dairy Technology Unit, 1988.
  2. Blais, C. The Facts About Milk Foam. Ricardo, [Online] November 2014;
  3. Chandan, R. Properties of Milk and Its Components. Dairy-Based Ingredients.; Amer Assn Of Cereal Chemists, 1997; pp 1-10.
  4. van Boekel, M.A.J.S. Effect of heating on Maillard reactions in milk. Food Chemistry. 1998, 62:4, 403-414.
  5. Walstra, P. Dairy Technology: Principles of Milk Properties and Processes; CRC Press, 2013.
  6. Dairy Alternatives – Soy, Almond, Coconut, Hazel, Cashew. Espresso Planet. [Online] April 2013;

Christina Jayson is a recent UCLA Biochemistry graduate about to embark on her Ph.D. journey at Harvard.

Vinny Dotolo

Vinny Dotolo is one half of the culinary duo dubbed as “Kings of Dude Food”. Alongside John Shook, the pair opened Animal, a meat-centric restaurant located in L.A.’s Fairfax Village. Following the success of Animal, the duo have since opened the equally acclaimed Son of a GunTrois Mec, and Petit Trois.

Vinny Dotolo

What hooked you on cooking?
Mainly the kitchen culture and obviously the delicious food and the never-ending learning process.
The coolest example of science in your food?
I guess science happens every day in our kitchens. Looking at it from a scientific perspective, I think the transformation and cooking of proteins.
The food you find most fascinating?
Eggs have always kept my mind racing.
What scientific concept–food related or otherwise–do you find most fascinating?
Emulsifications.
Your best example of a food that is better because of science?
Fermented foods.
How do you think science will impact your world of food in the next 5 years?
In general, I think understanding food and how and why things happen in the kitchen. Different techniques seem to be popping up constantly.
One kitchen tool you could not live without?
Vita prep.
Five things most likely to be found in your fridge?
Pickles
Cheese
Lemonade
Jam of some kind
The baby’s food
Your all-time favorite ingredient? Favorite cookbook?
Lemons are my favorite ingredient, they brighten everything up! Favorite cook book is tough. I have such a diverse collection but the one that changed my life and perspective and appreciation for food is the French Laundry.
Your standard breakfast?
Toast and coffee.

Ramen and the Perfect Egg

The arrival of autumn comes with the promise of changing leaves and chillier climates, often cueing our urge to prepare warmer meals aimed at combatting the frigid weather. One foolproof method that guarantees victory against the cold is a hot bowl of soup, such as ramen.  There are many variations of ramen but one dear to many hearts (and mouths) is tonkotsu ramen.  This style of ramen involves the boiling of pork bones for extended periods of time to produce a deliciously fatty and hearty pork broth that has an incredible depth of flavor.  The broth alone is what makes the ramen but the accoutrements that dress the soup are just as important.  Tonkotsu ramen is often served with slices of marinated, slow-cooked pork loin (chashu), enoki and wood ear mushroom, dried seaweed (nori), and green onions.  However, one of my favorite ramen toppings is the soy-marinated soft-boiled egg known as ajitsuke tamago.

Photo credit: Anne Regalado (My Bare Cupboard)

Photo credit: Anne Regalado (My Bare Cupboard)

Perfectly prepared ajitsuke tamago has a set outer layer of egg white with a delicate, intact silky egg yolk. However, achieving the ideal soft-boiled egg isn’t a trivial task.  The preparation of both hard and soft-boiled eggs culminates in the process known as protein denaturation.  Eggs themselves are nothing more than protein reservoirs and their exposure to heat disrupts the chemical and ionic bonds involved in maintaining their secondary and tertiary configurations causing them to unfold into linearized structures [1].   The unfolding of complex proteins into strings of amino acid chains through thermal energy transfer allows for the formation of new bonds between molecules that facilitate the transition of a raw, liquid egg into a cooked, solid egg [1]. Ovotransferrin and ovalbumin and are the most abundant proteins found in egg whites and their denaturation causes them to form tightly associated protein clumps that result in the solidification of the egg whites at 140°F and 180°F, respectively. [2,3]. Furthermore, the egg yolks will also become solid once they reach a sustained temperature of 160°F. Therefore, one must consider the balance of temperature and time to attain the characteristics of a perfectly soft-boiled egg.

Heat causes the phase transition of the egg from a liquid state to a water-insoluble state that's ready for eating! Photo Credit: SPIE

Heat causes the phase transition of the egg from a liquid state to a water-insoluble state that’s ready for eating! Photo Credit: SPIE

Timothy Ferriss, author of The 4-Hour Chef [4], conducted an experiment to dispel our egg boiling anxieties. He placed four eggs in a pot of water and brought it to boiling temperature (212°F); after 6 minutes he removed each of them in 2-minute increments.  His verdict? The sweet spot to achieve the perfect ajitsuke tamago egg consistency is somewhere between 6-7 minutes (see image below). I’d err between 5-6 minutes, as the salt from the soy-marinated will continue to “cook” the outer egg white layer.

Photo Credit: The 4-Hour Chef

Photo Credit: The 4-Hour Chef

If you enjoy the challenge of making dishes at home, check out this tutorial on how to make your own tonkotsu ramen!

Tonkotsu Ramen Broth

Ingredients

  • 3 pounds pig trotters, split lengthwise or cut crosswise into 1-inch disks (as your butcher to do this for you)
  • 2 pounds chicken backs and carcasses, skin and excess fat removed
  • 2 tablespoons vegetable oil
  • 1 large onion, skin on, roughly chopped
  • 12 garlic cloves
  • One 3-inch knob ginger, roughly chopped
  • 2 whole leeks, washed and roughly chopped
  • 2 dozen scallions, white parts only (reserve greens and light green parts for garnishing finished soup)
  • 6 ounces whole mushrooms or mushroom scraps
  • 1 pound slab pork fat back

Full recipe at Food Lab.

References cited

  1. Nelson, D; Cox, M (2012). Lehninger Principles of Biochemistry. 4th Ed. New York: W.H. Freeman
  2. Huntington JA; Stein PE (2001). Structure and properties of ovalbumin. Journal of Chromatography B 756 (1-2): 189–198
  3. Wu, J, Acero-Lopez, A (2012). Ovotransferrin: Structure, bioactivities, and preparation. Food Research Int 46: 480-487
  4. Ferriss, T (2012). The 4-Hour Chef. Boston: New Harvest

Anthony MartinAbout the author: Anthony Martin received his Ph.D. in Genetic, Cellular and Molecular Biology at USC and is self-publishing a cookbook of his favorite Filipino dishes.

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Apple Pie with Peanut Butter Mousse

The Science of Pie – May 19, 2013
People’s Choice Award
Elan Kramer, Caleb Turner (Team “Insert Team Name Here”)

This student duo thought outside the box with this creative apple and peanut butter pie. To create the ultimate peanut butter experience, the team experimented with the effect of egg white content on the texture and density of the peanut butter mousse.

TeamInsertTeamNameHere

photos courtesy of Patrick Tran

Egg white content affects mousse texture. (A, B) Team “Insert Team Name Here” visualized the air bubbles incorporated into peanut butter mousses prepared with different amounts of egg whites. (C) Using image processing techniques, they calculated the mean (red) and median (blue) air bubble areas as a function of egg white content. Their results show that there is indeed an optimal egg white content for creating an light, airy mousse. (D) An egg white is made up of many proteins suspended in water. Whipping incorporates air bubbles into the egg whites, causing the proteins to unfold as they are exposed to air. Denatured proteins [link to ceviche recipe] form networks at the liquid/air interfaces that stabilize air bubbles within the egg white foam.

The Recipe
Frozen apple pie with peanut butter mousse

1 large store-bought graham cracker crust

For the apple layer:
2 tbsp unsalted butter
3 firm-textured cooking apples*, peeled, cored, and sliced
¼ cup granulated sugar
1 tsp fresh lemon juice
2 tbsp powdered sugar
*Team “Insert Team Name Here” used Pink Lady and Granny Smith apples

For the peanut butter mousse:
1 cup heavy cream
8 ounces cream cheese, softened
1 cup smooth peanut butter
¾ cup granulated sugar
½ cup firmly packed light brown sugar
2 tsp pure vanilla extract
2 large egg whites

For the topping:
1 cup heavy cream
1 tbsp powdered sugar
½ cup finely chopped salted dry-roasted peanuts
2 graham crackers, crushed
1 1/2 tsp cinnamon

To prepare the apple layer, melt the butter in a large sautée pan. Stir in the apples and granulated sugar and cook over medium heat, stirring often, until tender, about 5 minutes. Stir in the lemon juice and powdered sugar and cook, stirring, for 1 minute longer. Remove from the heat and refrigerate.

To make the peanut butter cloud layer, use an electric mixer to whip the heavy cream until it holds semi-firm peaks. Cover and refrigerate.

Using the mixer, beat the cream cheese and peanut butter together until smooth. Gradually beat in the sugars, then the vanilla. The mixture will be lumpy, like cookie dough. Add the whipped cream to the peanut butter mixture, slowly blending them together with the electric mixer until smooth.

Clean and dry the beaters. Using a clean bowl, beat the egg whites until they hold stiff peaks. Fold the whites into the peanut butter mixture with a rubber spatula until evenly blended. Put mixture into the pie crust, cover loosely with aluminum foil and freeze for at least 5 hours.

When you’re ready to serve the pie, take it out of the freezer and top with the refrigerated apples. For the topping, add the powdered sugar and 1/2 teaspoon to the cream and use an immersion blender or mixer to whip. Spread over the top of the pie and sprinkle with peanuts, graham cracker crumbs, and remaining cinnamon.

Recipe adapted from Cookstr: Frozen Apple and Peanut Butter Cloud Pie

Baking Without Eggs

With the Science of Pie coming up in just a few weeks, we’ve been spending a lot of time thinking about baked goods. And one ingredient in particular has really captured our imagination—the egg! In the realm of baked goods, eggs are highly revered for their binding and leavening abilities. The fats and proteins within an egg can also contribute to important properties like moisture, texture, and mouthfeel [1]. Read more