Lab Bench: Silky Bavarian Cream

The Art.
    Best Friend Hanako has been my steadfast companion on many wonderful baking adventures, but the one I love best is the time we made Bavarian cream. We had just thrown together some spice cake cupcakes, and I had found a new Bavarian Cream recipe for us to use as a filling. As usual, we were focused more on gossiping and giggling rather than baking, and I didn't have high hopes for our end product. We didn't even follow the recipe entirely. However, the resulting Bavarian cream was one of those happy accidents you experience in life that you reminisce about for years to come. It was silky, rich and wonderful. I have attempted to recreate this cream several times with limited success, and each time it falls short of my expectations and I fall into a deep Baking Depression. After my most recent attempt, I decided enough was enough. Today, I will share with you what ensues when a scientist has trouble with a recipe.

The Science.
   This Bavarian Cream is made up of two components: a whipped cream and a vanilla custard. To be honest, the root of all my problems lies within the custard component. I hypothesized that there were a few variables that had changed between the first Bavarian cream and the subsequent batches. First, I know for a fact that I didn't use anywhere near as much gelatin as the recipe calls for. Second, I didn't use a thermometer while cooking the custard, nor record how long I cooked it. (That part really infuriates me.) Third, I'm not sure if I used whole milk or 1%. And fourth, Best Friend Hanako reminded me that I had originally chilled it overnight, because I knew she would have no patience for stirring over a double boiler when she came over.
     Custards can be very sensitive to heat, and according to those who know, they should only be cooked to 170-175^oF [1]. Any higher, and the eggs will begin to "break," and you'll end up with a lumpy custard. Straining through a sieve will only take out large clumps caused by under-stirring, so there's no going back after your eggs have curdled. For this recipe, I needed to figure out the perfect cook time, thickening agent, and chill time to create a custard that is thick enough to be stable once blended with the whipped cream, yet gently cooked so it maintains a rich, silky texture. 
    After several days of painstakingly altering the custard recipe, I finally got fed up with the whole thing, and decided to take a step back. I remembered when my Aunt first taught me to make custard, and threw all the custard ingredients together in a pan and stirred constantly with a spatula. When the mixture just started to bubble (which I admit was way above 175^oF), I strained it and allowed it to set overnight. Voila! Perfect custard, and no thermometers needed.


The Recipe. (Adapted from [2])

6 egg yolks
1 cup  plus 2 tablespoons powdered sugar
2 cups whole milk
2 teaspoons vanilla extract
1 (1/4oz) envelope gelatin
1/4 cup boiling water
1 1/2 cups 40% heavy whipping cream
1 teaspoon cornstarch

    In a large bowl, beat together egg yolks and powdered sugar until light yellow and fluffy. Bring milk and vanilla to a scald in a saucepan. Slowly add ladles of milk to the egg yolks, constantly stirring until all the milk is combined. Tempering the eggs like this prevents them from cooking up in lumps, and produces a silky texture. Stir the custard constantly over low heat with a spatula, carefully scraping the entire bottom of the saucepan to prevent it overcooking on the bottom. When the custard begins to coat the spatula and just begins to bubble, remove from heat.
    In a small bowl, stir gelatin into 1/4 cup boiling water until dissolved. Slowly add to warm custard while stirring. Strain custard through a wire mesh sieve into a bowl, cover surface with waxed paper, and chill overnight.
    The next day, make the stabilized whipped cream. Chill a large metal bowl and beater blades in the freezer for 10 minutes. Add some ice and water to a slightly larger bowl to create an ice bath, and set the chilled metal bowl inside it. Whip the cream on medium-high until soft peaks stand in the bowl. Add the cornstarch, and continue to beat on high until stiff peaks form. Be careful not to over-whip, as the cream will curdle.
    Before combining the custard and the cream, the custard must be whipped to make the texture more pliable so the whipped cream can be folded in. This can be done by either stirring with a whisk or beating it on low for a couple minutes. Fold the whipped cream into the custard, and stir until smooth. Store Bavarian cream in the refrigerator for up to 3 days.


1. Sawicki, Laura. "Cooking Basics-- How to Make Custard." Edible Austin. Available here.

2. Recipe by Nadia Hassani, in Spoonfuls of Germany. Available here.

Blooming Rose Cupcakes

The Art.
     So many cupcake toppers include rose decorations, but they usually require advanced skills with buttercream or fondant. I love this decorating technique because it is so stunning, yet doesn't require much decorating skill or special tools. In addition, covering a cupcake in real rose petals gives it an ethereal and romantic quality that simply can't be matched. While newbies can use this decorating technique, making the sugared rose petals will take some time and patience. In the end, you'll find it's worth it.
    I completed the rose theme with rose-flavored angelfood cake, topped with a billowy meringue icing.  The delicate texture and airiness of these cupcakes perfectly compliments the rose flavor. For presentation, I made a bouquet from the leftover flowers and wove ribbons around the plates.

The Science.

Structure of beta-Damascenone

    Rose scent is the most highly coveted floral scent in the perfume industry. The fragrance is exceedingly complex, varying from plant to plant and from season to season. Rose petals produce scent by releasing volatile compounds, which are made up of various terpenoids, phenylpropanoids, and fatty acid derivatives [1,2]. These compounds evaporate into the air and insects are drawn to the blooms, thus increasing the plant's pollination. Beta-Damascenone is an aromatic compound named after Rosa Damascena, and is the most common additive for rose flavor and fragrance. Through genetic manipulation, scientists have discovered several genes expressed in rose petals that are responsible for producing fragrance, exposing a link between bloom pigmentation and increased scent [2]. Sadly, most roses sold for floral arrangements have been bred for bloom color and size, and usually have little fragrance.

The Recipe.

Sugared Rose Petals:
One dozen organic roses in desired color
1 egg white
1 cup sugar

     Make sure your roses are grown organically and are not coated with anti-fungals after harvest. Gently pluck petals from 6 roses, discarding any browned or disfigured petals.  Rinse with water and pat dry. 

    Using a paintbrush, paint a thin layer of egg white on each petal, then dust with sugar, knocking off the excess.  Place on paper towels and allow to dry 1-2 hours. Store in the refrigerator in a single layer, and use petals within 24 hours.

Rose-flavored Angelfood Cupcakes:
1/3 cup cake flour
1/2 cup sugar
5 large egg whites*
1/4 teaspoon salt
1/2 teaspoon cream of tartar
1-2 teaspoons rosewater




    Preheat oven to 300^oF. Line a cupcake tin with paper liners. Sift flour twice, then sift together with 1/4 cup sugar. Sifting several times aerates the flour so the cake will be lighter. In a large bowl, beat egg whites on medium-high speed until frothy. Add salt and cream of tartar and beat until peaks barely form. Gradually beat in remaining 1/4 cup sugar and rosewater, mixing until soft peaks form. Gently fold in a third of the flour/sugar at a time, stirring until incorporated after each addition. Fill cupcake tin to the top with batter. Lift and drop the pans onto the counter a couple times to release air bubbles. Bake on center rack until tops are springy and toothpick inserted in center comes out clean, about 25  minutes.** Cool 10 minutes, then transfer to cooling rack until room temperature. Can be stored in an air-tight container in the freezer for two weeks. Yields 12 cupcakes.
*Save all of your egg yolks for the Bavarian cream recipe I'll give you later.
**If you have raucous children, pets, or significant others, tie them to a tree outside while the angelfood bakes.  The air in the beaten egg whites is what makes angelfood rise, so loud clatters will cause the cake to fall. Also, don't slam the oven door or bang pans around. Then you'll have no one to blame but yourself when your cupcakes fall, and you will have tied your loved ones to a tree for nothing (an act that is much easier to explain to social services while they're eating a fluffy cupcake).

Seven-Minute Meringue Icing:
1/2 cup sugar
3 tablespoons water
1 large egg white
1/8 teaspoon cream of tartar
Pinch of salt
1/2 teaspoon rosewater

    Bring one inch of water to a simmer in a medium saucepan.  Combine all ingredients in a large metal bowl, then set over saucepan to create a makeshift double-boiler.  Blend on high speed until soft peaks form, about 5 minutes. Wear an oven mitt on your hand that is stabilizing the bowl, to protect it from the steam. Remove from heat, add rosewater. Beat until icing is cool and billowy with stiff peaks, about 2 minutes.

Assembly:
    Frost cupcakes with a generous dollop of meringue icing and spread with spatula. Begin inserting rose petals into the icing around the edge of the cupcake. Work inward in a spiral until you reach the center.

I found that inserting 5 large petals on the periphery and 3-4 smaller ones in the center looked nice. Altering the angle at which you insert the petals will determine whether the cupcake looks more like a rosebud or a fully bloomed rose. Cupcakes can be stored in the refrigerator one day.

1. Flament, I. et al. "Volatile constituents of roses: characterization of cultivars based on the headspace analysis of living flower emissions. In: Teranishi R, Buttery RG, Sugisawa H (eds) Bioactive volatile compounds from plants." American Chemical Society (1993): 269-281.
2. Yan, Huijun et al. "Isolation and identification of a putative scent-related gene RhMYB1 from rose." Molecular Biology Reports 38.7 (2011): 4475-82.

Mustache-querade Cupcakes

The Art.
    It is Labmate George's birthday this week, and I wanted to make him extra special cupcakes. He requested a simple yellow cake with chocolate frosting, but this wasn't fancy enough for me. So, I sat down and asked myself, what kind of cupcake toppers would he like? Labmate George is a Hipster of the Hippest Sort, and trying to come up with an idea that he would consider "cool" made me feel painfully mainstream and frankly a little depressed. Finally, I was struck with an idea that I believe is utter brilliance: chocolate mustaches on a stick! I love the idea of all my labmates holding up edible Hercules Poirot mustaches to their faces. Hilarity is bound to ensue.

The Science.
    All jokes aside, it is very important for every baker to know that all chocolates are not created equal. This goes double for candymaking. Every type and brand of chocolate has a different ratio of cocoa solids, cocoa butter, milk fat, and milk [1]. Altering the ratios of these ingredients changes the melting temperature of the chocolate, and the texture it will have when it cools again. Dark and bittersweet chocolates have a high amount of cocoa solids and no milk, so they are harder at room temperature than milk chocolate. Baking bars are preferable to candy bars when melting, because they contain less sugar and fat and will create a nice hard confection.

    Another factor that must be considered are emulsifiers. These are fatty compounds, such as soy lecithin, that are added to chocolate to keep the fats from separating from the cocoa solids. Chocolate chips have more emulsifiers than bar chocolate, improving their texture and preventing the chips from sticking together. However, this also makes them undesirable for candymaking because the high fatty content inhibits the chocolate from hardening effectively. Inexpensive bar chocolates also contain more emulsifiers than pricier bar chocolate, because it allows the manufacturer to use less cacao [1]. If you take any of my advice from this blog post, please please please buy a good-quality, 60% cacao baking bar for your candymaking. NOT chocolate chips. Thank you.

The Recipe.

Yellow Cake:
2 1/4 cups cake flour
2 1/4 teaspoons baking powder
1/4 teaspoon salt
3/4 cup salted butter
1 1/2 cups sugar
4 eggs
1 1/2 teaspoons vanilla
1 cup buttermilk

    Preheat oven to 350^oF and line two cupcake tins with paper liners. In a medium bowl, comine flour, baking powder, and salt. Beat butter in large bowl on medium-high until fluffy, then gradually beat in sugar. Beat eggs in, one at a time. Stir vanilla into buttermilk. Alternately add flour mixture and buttermilk to butter/sugar/egg mixture while beating on low speed.  Beat an additional 30 seconds.
    Using a 1/3 cup measure, fill cupcake tins with batter.  Filling with a measuring cup is an efficient way to ensure that all the cupcakes have the same amount of batter and will bake evenly. Lift and drop the cupcake tins on the counter a couple times to eliminate bubbles in the batter. Bake on center rack for 20 minutes, or until a toothpick inserted into cake comes out clean. (Recipe modified from [2]).

Fluffy Chocolate Buttercream:
1 cup salted butter
1 cup vegetable shortening
1 cup cocoa
4-6 cups powdered sugar

    In a large bowl, beat together butter and shortening on medium speed until fluffy.  Beat in cocoa. Gradually beat in powdered sugar, until icing becomes thick enough for piping. I look for stiff, jagged peaks as my indicator. Adding the sugar in increments results in better incorporation into the butter, so you can use less sugar for the same consistency. If the frosting tastes too sweet and feels grainy, add a couple tablespoons of milk.

Mustache Toppers:
8 oz. Ghirhardelli 60% cacao bittersweet baking bar
25 pretzel sticks

   Place chocolate in a microwave-safe bowl and heat in microwave in 30 second increments, stirring inbetween, until only some solid chunks remain.  Let sit at room temperature 10 minutes, then stir.  Melting the chocolate in this way will ensure that you do not overheat and thicken it.
    Draw a mustache stencil on carstock paper and cut it out. Optimal size is 2-3" across. Use stencil to outline 24 mustaches on a sheet of waxed paper with permanent marker. Take care not to smudge the ink until it's dry.  I used a VWR indelible lab marker, because I'm a nerd. Turn the waxed paper ink-side down and place on top of cardboard or baking sheet.

    Spoon some melted chocolate into a resealable plastic sandwich bag, seal shut, and snip off the tiniest bit of the bottom corner to form a piping bag.  Pipe a chocolate border over your outlines on the waxed paper. Fill in with a zigzag motion, and smooth with a toothpick.  Mustaches should be thick, raised at least 1/4" above the surface of the waxed paper.  If they are too thin, go over them again with your piping bag. Place in refrigerator or freezer until hardened, about 20 minutes.
   To attach sticks to mustaches, dip the top 1/2" of a pretzel stick in melted chocolate, and press onto a cooled mustache, slightly to the side. Use a designated "gluing" pretzel to dab more chocolate around the pretzel stick to ensure that it is attached. Repeat with the remaining 23 mustaches. Eat your gluing pretzel, because it is delicious. Place mustaches in refrigerator until ready to top cupcakes.

Cupcake Assembly:
    Allow cupcakes and buttercream to reach room temperature. Using a piping bag and 1M tip, pipe a swirl on top of each cupcake as described in my previous tutorial. Stick a mustache topper into each cupcake and serve with a can of PBR, if desired.

1. Galvin, Lori et al. Test Kitchen Favorites. Brookline, MA: America's Test Kitchen, 2006.
2. Garrett, Toba. The Well-Decorated Cake. New York, NY: Sterling Publishing, 2004.

Tutorial: 1M Swirl

The Art.
    This is the first in a series of cake decorating tutorials that I'm very excited about. Each time I create a post that uses a standard decorating technique, I will post how-to directions for it a few days before. I think it's important to demonstrate the piping techniques that are used to decorate cakes, cupcakes, and cookies in a step-by-step format, especially for all my readers who are new to decorating.

   The classic 1M swirl is a must-have technique in a cupcake decorator's arsenal.  It is so quick and easy, but still elegant. The term "1M" refers to the decorating tip size that is required. I use a Wilton 1M tip, which can be found at Hobby Lobby or at Wilton's website. This tip can be used for many other techniques, like making large drop flowers, stars, or cake borders.  Definitely worth the $2 investment. This tip can also be used to decorate with a wide range of icings, from chocolate ganache, to whipped cream, to buttercream.

The Science.

    A very important factor for piping beautiful decorations is making sure your icing is the right consistency. When icing is concerned, temperature and consistency go hand in hand. Today, I am demonstrating the 1M swirl with buttercream icing, which is my staple. My recipe uses a mixture of butter and shortening, which simultaneously gives it a nice buttery flavor and a wider temperature range in which it can be used to decorate. All-butter recipes are more difficult to decorate with and transport than those made with shortening. Butter is not a pure fat, but rather an emulsion of oil and water held together by milk protein emulsifiers. It is a hard solid at temperatures below 60^oF because of its high saturated fat content, so cool all-butter buttercream cannot be piped. However, butter also has a low melting temperature of only 90^oF, which means that it will make icing become oily and soft if left at room temperature for a while [1]. Shortening, on the other hand, is full of hydrogenated fats and is fairly soft at cold temperatures, yet doesn't melt until about 117^oF [2]. These qualities make it an ideal fat for decorating icing, but not so great on the flavor front. By blending together butter and shortening in buttercream, you can achieve the best of both worlds and have buttery flavor and temperature tolerance.

The Recipe.

Fluffy Buttercream
1 cup salted butter, room temperature
1 cup vegetable shortening
5-7 cups powdered sugar
2 teaspoons vanilla

    In large bowl, beat together butter and shortening on medium speed until fluffy. Beat in powdered sugar, one cup at a time. Add sugar until icing makes stiff, jagged peaks. Beat in vanilla. If icing tastes too sugary or grainy, add a couple tablespoons of milk. Use immediately or store in an airtight container for up to two weeks. Makes enough icing for one 9" round cake or 24 cupcakes.

1M Swirl Technique:
   Place a 1M decorating tip in a piping bag and fill with icing, twisting the top shut. Beginning at the outer edge, anchor the frosting on the cupcake by holding the tip at the surface and applying pressure to the bag. Once anchored, raise the tip slightly above the surface.
Pipe around the periphery with constant pressure until you reach your starting point. Continue to pipe, slightly overlapping your first round of icing. Keep on going around until you reach the center of the cupcake. When you come to the point where you want your swirl to end, stop pressure on the piping bag, push the tip down slightly to anchor the end of the swirl, then pull up to release. Please note that I am left-handed, so all you righties might want to mirror what I do in the photos.









1. American Baking Essentials Course 201. "Butter, Shortening, and Oils: The Fats We Bake With." The Prepared Pantry, 2005.
2. O Chef, "Turning the Heat up on Crisco (and Lard)." http://www.ochef.com/1157.htm

Summer Rhubarb Cake

The Art.
    My grandmother has always been protective of her rhubarb plants, to put it mildly. I have never been able to figure this out, since you can't kill the stuff. You can try and corral it into one part of your garden and not only will it take over completely, it will grow under cement foundations and show up in your neighbor's yard on the other side. Nevertheless, my aunt would have to sneak into Grandma's garden at the break of dawn on summer mornings if she wanted to snag a few stalks for her famous rhubarb cake. When the family would visit for dinner that evening, my aunt would serve squares of warm rhubarb cake with a scoop of vanilla ice cream dribbling over the edges. Grandma would eye her plate suspiciously until we all felt sufficiently uncomfortable, then inquire where my aunt got the rhubarb. The grocery store, Grandma, the grocery store. We'd all smirk down at our plates while we tucked into our favorite summer dessert.
    To be honest, the real beauty of my aunt's rhubarb cake is that you virtually can't mess it up. I've dressed the recipe up a bit over time, but you can throw everything in a bowl and stir it with a fork and it will turn out fine. In fact, my aunt would add a tablespoon of vinegar to a cup of milk and use that instead of buttermilk in a pinch. This is a homey, simple cake that goes hand-in-hand with the heartiness of the rhubarb plant.

Structure of Oxalic Acid

The Science.
    However, there is a darkness that lingers within this plant. Rhubarb (Rheum rhabarbarum L.) is sour and sinister. Its tissues harbor oxalic acid, a dicarboxylic acid that is a weak poison. While this compound is found in many foods like sugar beets and spinach, the leaves of the rhubarb plant contain up to 20 times more oxalic acid than spinach leaves, and should not be eaten. Conversely, the rhubarb stalks have very little oxalic acid and are considered benign. The roots of the rhubarb plant have also been used in Chinese medicine since the 16th century [1]. But today, we will enjoy its tart flesh in a tasty cake to celebrate heartiness and surviving against the odds!

The Recipe.

Cake:
2 cups flour
1 teaspoon baking soda
1 teaspoon salt
1 cup brown sugar
½ cup butter
1 large egg
1 cup low fat buttermilk
1 teaspoon vanilla
2 cup chopped rhubarb

Topping:
1 cup brown sugar
1 cup chopped pecans
3 tablespoons melted butter

    Combine flour, baking soda, and salt in a medium bowl. In a large bowl, cream together butter and sugar on medium speed. Add egg and vanilla, beat until combined. Alternately add flour mixture and buttermilk while beating on medium speed until just combined.

Fold in rhubarb, pour into greased 9X13 pan. In a small bowl, mix topping ingredients and sprinkle evenly over batter.

 Bake at 350^oF for 45min. Serve warm with vanilla ice cream. And don't tell Grandma.

1. Donald G. Barceloux, Rhubarb and Oxalosis (Rheum Species). Disease-a-Month, Volume 55, Issue 6, June 2009, Pages 403-411.

Lemon polka dot sugar cookies

The Art.
    I was designing my blog banner the other day, and found this beautiful yellow polka dot background. It is so simple and cheerful, an embodiment of what I want my blog to be. However, I didn't have a photo of baked goods that would match the lemon yellow of the banner. One of my "delightful eccentricities" is that I like things to match. So, I decided to make iced sugar cookies with a yellow polka dot pattern. Lemon flavor is so wonderfully summery as well, I decided I couldn't go wrong! For presentation, I tied the cookies up with yellow and white daisy trim I found in my sewing box.

The Science.
    When I was a child, my grandmother's friends taught me to make royal icing by beating together egg whites and powdered sugar. More recently, royal icing recipes use meringue powder instead of egg whites, and I assume this is because people are worried about bacterial contamination in their eggs. I hypothesized that adding lemon juice to the egg whites and beating them together would lower the acidity and kill any bacterium present. I performed a rough calculation. The average egg white has a volume of 2 tablespoons, and a medium lemon has 3 tablespoons of juice. My royal icing recipe calls for two egg whites and and the juice of one lemon, so the ratio of egg white to lemon is 4:3. The pH of an egg white can increase over time, but is approximately 7.5, while lemon juice has a pH of 2 [1]. Thus, the approximate acidity of my egg/lemon mixture would be pH 6. Not very acidic, is it? Additionally, a group in Liverpool did a study a few years ago and ascertained that a pH below 2.5 is required to kill E. coli [2]. So, my lemon juice will not kill bacterium in my egg whites. There is really no need for concern, however, since pasteurized eggs are available in the U.S., and also because the sugar content in royal icing is so high.

The Recipe.

Sugar cookies:
2 1/2 cups all-purpose flour
3/4 teaspoon salt
3/4 cup salted butter, softened
3/4 cup sugar
1 large egg
1 teaspoon vanilla
zest from one lemon (optional)

    In a small bowl, combine flour and salt. Beat together butter and sugar in a large bowl on medium-high until pale and fluffy. Beat in egg, vanilla, and lemon zest. Reduce speed to low and add flour mixture, mixing until just combined. Cover and chill dough at least one hour.

Put oven rack in middle position and preheat oven to 350°F. To roll out the cookie dough, I prefer to place it between two pieces of waxed paper rather than flour my surfaces, so I don't get flour everywhere and make my cookies grainy.

Roll out dough with rolling pin until it is 1/4" thick. Cut out as many cookies as possible from dough with cookie cutters. I used fluted square cookie cutters, to set off the polka dot pattern.

Gather scraps and re-roll, cutting out more cookies. Transfer cookies to 2 ungreased large baking sheets, arranging cookies about 1 inch apart. Bake cookies until edges are golden, 10 to 12 minutes, then transfer to racks to cool completely [3]. 

Royal Icing:

2 large egg whites

3 tablespoons juice from one lemon

3 to 4 cups powdered sugar

    Beat together egg whites and lemon in large bowl at medium speed until slightly foamy. Gradually beat in sugar on low speed until stiff peaks form. This is your "outlining" icing. Once done outlining your cookies, thin this icing with a few tablespoons of water to make "flooding" icing.

Decorating:

    Once cookies have cooled, dye the outlining icing bright yellow (or your favorite color), reserving some white icing for the polka dots. I used Wilton Icing Colors lemon yellow. Spoon some outlining icing into a plastic sandwich bag, and carefully snip off the tiniest bit of the bottom corner with a pair of scissors. A little goes a long way! Use this as your icing bag and outline the border of your cookies.

    Thin the rest of the icing with a few tablespoons of water, enough so that it will pool and "flood" your cookies out to the outline you made, without being so watery it will run over. Spoon flooding icing onto center of cookies and allow to flood the entire cookie. While the flooded cookies are still wet, fill another bag with the white outlining icing and snip the corner off. Dot the white icing on cookies in a grid pattern to make polka dots. Doing this while the cookies are still wet will make the dots level with the flooding icing and gives it a smooth finish. You can experiment with dot sizes by squeezing more or enlarging the opening in your bag. Allow cookies to dry overnight.

1.  http://food.oregonstate.edu/learn/egg.html
2.  Zhu H. et al., Bacterial killing in gastric juice--effect of pH and pepsin on Escherichia coli and Helicobacter pylori. J Med Microbiology, 2006 Sep;55(Pt 9):1265-70.
3.  Sugar cookie recipe adapted from Gourmet Dec. 2005, available here.