Meringue Christmas Tree

The Art.
    For my holiday party this year, I wanted to make an edible topiary to complete my table decor. I came across an idea for a beautiful meringue cookie topiary, so I decided to try my hand at making meringues. I was a little daunted by the three hour time commitment at first, but the small amount of active time meant that I could spend those three hours doing chores (read: watching tv). The cookies turned out wonderfully--nice and airy and not too sweet. Making the topiary was a breeze, especially because I used a couple cans of spray food color to tint the cone and the cookies.  This also meant I could rest easy knowing that everything was food-safe.

The Science.
    Meringue cookies are so light and crisp because they are mostly beaten egg whites and sugar. Egg whites are composed of water and protein, and when they are beaten at high speed the proteins begin to stick together, or "aggregate." The aggregated proteins make up a film that coats the air bubbles, and helps retain the bubbles in the mixture. Different conditions can cause egg whites to foam more efficiently, such as increasing the salt, acidity, and temperature [1]. This is why most meringue recipes call for room temperature eggs and cream of tartar. Pasteurization treatments can also increase the foaming performance of egg whites. Several groups have found that irradiating or ozonating egg whites increases protein aggregation and foaming, in addition to the sterilizing effects [2,3].

The Recipe.

Meringue cookies: (Makes 50)
3 large egg whites, room temp.
1 tablespoon pure vanilla extract
1/4 teaspoon cream of tartar
3/4 cup superfine granulated sugar
red spray food color

    Preheat oven to 200°F. In a large bowl, beat together egg whites, vanilla, and cream of tartar until soft peaks form. Gradually beat in half of the sugar, then beat on high until stiff peaks form. Fold in remaining sugar.

     Cover two baking sheets with parchment paper, sticking the paper down at the corners with a dab of meringue. Spoon meringue into an icing bag fitted with 1M tip, and pipe 2-inch stars onto baking sheets, 1/2 inch apart.  For the red cookies, spray 1/4 of the unbaked meringues generously with the red food color. I used Wilton Color Mist. (I really love this stuff, because tinting a batch of batter or icing deep red takes so much dye. By just spraying the tops, you can achieve the dark color quickly with less material.) Bake 2 hours, switching the top and bottom racks halfway through. After baking, leave cookies in oven to cool 1 hour with the door held ajar a couple inches with a spoon handle.

Topiary:
15" Styrofoam cone
green spray food color
1/2 cup powdered sugar (or royal icing)

    While cookies are baking, begin preparing your Christmas Tree. Place the Styrofoam cone on parchment paper and liberally spray with the green food color. Allow to air-dry several hours. In a small bowl, make an edible "glue" by adding a few drops of water to the powdered sugar.



    To affix the cookies to the "tree," dab a small amount of the sugar glue on the back of each cookie and press it on the tree. 

    For this spiral pattern, you can begin by making a spiral with the red meringues first, then fill in the rest with the white ones. Or, you can disperse the red ones evenly to look like ornaments.

    The meringue topiary was a big hit at the party, and added nice height to my holiday treats display. I highly recommend using color and height to liven up your edible spread. A little extra effort goes a long way to impress your guests.

1. O Chef, "Beating Egg Whites into Submission." http://www.ochef.com/223.htm
2. Liu, X. et al. "Effect of irradiation on foaming properties of egg white proteins." Poult. Sci. 2009, 88(11) pp 2435-41.
3. Uzun, H. et al. "Effects of ozone on functional properties of proteins." Food Chem., 2012, 134(2), pp 647-54.