Meringa con Zabaglione

Today in lab we made meringa with zabaglione and berries. This dessert has a meringue base with zabaglione (custard) and fresh berries on top.

Meringa

Materials:

• KitchenAid stand mixer
• Kitchen thermometer
• Measuring cups and spoons
• Liquid measuring cup
• Baking sheets
• Parchment paper
• A spoon
• Small pot

Ingredients:

• 5 Egg whites
• 1 cup of superfine sugar = 1 cup and 2 tsp of white sugar
• ½ cup of water
• ¼ tsp of cream of tartar

First the oven was preheated to 200 °F. Then we put the 5 AA grade eggs in a bowl with warm water because the eggs need to be at room temperature. Once the eggs were not cold anymore, we separated the egg whites from the yolks. To do this process, we gently cracked the eggs keeping the yolk in one half of the shell. In order to get all the egg whites into the stainless steel bowl, we transferred the yolk from one half of the shell to the other half, allowing the egg whites to drip into the bowl.

Next we put the whisk attachment on the KitchenAid stand mixer used this machine to beat the egg whites. Then we added ¼ of teaspoon of cream of tartar to the egg whites and continued beating the egg white mixture until soft peaks formed. Below is a picture of our droopy soft peaks.

Now that we have soft peaks, the next step is to mix ½ a cup of water and superfine sugar in a small pot. To make the superfine sugar, we blended 1 cup and 2 teaspoons of white sugar in the food processor. This process grinds the sugar into small pieces which makes superfine sugar. Then we put the small pot on a burner at low temperature. We kept mixing the sugar and water mixture with a whisk until the sugar dissolved. We also put a binder clip on the side of the pot for the kitchen thermometer to lean on. We did this so the tip of the thermometer does not touch the bottom of the pot for a more accurate reading and so the mixture does not burn us. The kitchen thermometer constantly measured the temperature of the sugar-water mixture. While the mixture was heating up, we put cool water in a glass bowl which will be useful for a later step. Once the thermometer read 240 °F, we took a spoon full of the mixture (syrup) and poured it into the cool water. Then we began molding the syrup and it formed into a ball (soft ball stage). Below is a picture of our cute little ball.

It was exciting that the cooled syrup turned into a ball because that meant it was time to pour the syrup into the beaten egg whites (our soft peaks). We began whipping the beaten egg whites again using the stand mixer and poured the syrup into the beaten egg mixture. We continued beating the mixture until we got stiff and glossy peaks. Below is a picture of our glossy stiff peaks.

Then we lined 4 baking pans with parchment paper. Once the baking pans were lined, we scooped spoonfuls of the meringue onto the parchment paper. We then used the back of the spoon to shape the blobs into little cups. All together we made 8 meringue cups. Now the meringue was ready to go in the oven for 2 hours.

While the meringue was baking, we washed strawberries, blueberries, and raspberries. We also sliced the strawberries into pretty slivers. About 20 to 30 minutes before the meringue was finished baking, we began making the zabaglione.

Zabaglione

Materials:

• Medium saucepan with lid
• Whisk
• Measuring spoons
• Stainless steel bowl

Ingredients:

• 5 egg yolks
• ½ cup of superfine sugar = ½ cup and 2 teaspoons of white sugar blended in a food processor.
• 2 teaspoons of vanilla extract

First we put about an inch of water in a medium saucepan and then covered the saucepan with a lid. Then the saucepan was put on the burner and the water was brought to a boil. Once the water was boiling, we lowered the temperature of the burner so the water simmered and took the lid off of the saucepan. Then we put the stainless steel bowl in the water and whisked the 5 egg yolks, the ½ cup of superfine sugar, and 2 teaspoons of vanilla extract. We kept whisking to get the custard thicker and lowered the temperature if the water was boiling to prevent making scrambled eggs.

After about 5 minutes the zabaglione started to thicken but did not pass the 8-second test. The 8-second test is where we lifted the whisk and counted to see how long it took for the dripping zabaglione to flatten. When it takes 8 seconds to flatten, the zabaglione is finished cooking. Since our zabaglione did not pass the test, we kept whisking. About 3 minutes later, the zabaglione passed the 8-second test.

Next we took the stainless steel bowl out of the water and kept whisking the zabaglione. We did this so the temperature of the zabaglione would drop and so the zabaglione would continue to thicken. Our zabaglione did not cool down a lot, so we put the steel bowl in a glass bowl with cool water to lower the temperature. Unfortunately, our zabaglione over thickened from the hot stainless steel bowl. For the future we recommend to not wait until the zabaglione passes the 8 second test because the zabaglione keeps cooking in the stainless steel bowl. In the end, our zabaglione was overcooked and became thick like icing.

Assembling the Tarts

To assemble the tarts, we put the zabaglione in a zip lock bag in order to pipe it onto the meringa. We cut the corner of the bag and began piping the zabaglione into the cup shaped meringa. Then we decorated the tart by putting 3 strawberries, 2 blue berries, and 1 raspberry on top of the zabaglione. Below are pictures of our beautiful tarts!

Video

Chemistry Questions

• What chemical changes occurred when you made the meringue/meringa? What did you observe that told you these chemical changes were happening?

When we made the meringa the sugar turned into syrup and the egg white protein were denatured. The sugar water mixture turned into syrup when it reached 240 °F. This was seen when a scoop of syrup was poured in cool water and the syrup could be molded into a ball.  The egg white proteins began denaturing from whisking because the it introduces a lot of air into the protein mixture. The protein will stiffen (coagulate) and the egg whites will go from a clear liquid to a white foam (semisolid). The egg white proteins continued to denature when the cream of tartar was added and whisked into the mixture. The cream of tartar is an acid which unfolds the globular proteins and pushes the side chains away. This created fluffy soft peaks. When the hot syrup was added to the soft peak beaten egg whites, the heat of the syrup and additional mixing caused more denaturation/ coagulation of the proteins. This was seen when the soft peaks turned into glossy stiff peaks. The cooking of the meringa in the oven also caused the proteins to coagulate. This caused the meringa cups to be hard.

• What was responsible for the thickening of the zabaglione as you stirred it over the hot water bath?

The stirring and heat from the water bath caused the proteins in the egg yolks to denature. The vanilla extract also diluted the protein which makes it harder for the denatured proteins’ hydrophobic parts to clump with other proteins’ hydrophobic parts. It also creates a weaker protein network and the coagulated protein network is fragile. The denaturation and coagulation of the protein in the egg yolks were responsible for the thickening of the zabaglione. When the proteins unravel and then clump together, they form a thickened custard.

• Overheating (too fast and or too hot) the zabaglione can leave you with “scrambled eggs” – a lumpy grainy mess of clumps in watery liquid. What is happening in this case?

In this case the proteins curdle instead of thicken. Curdling is when the protein denatures and then coagulates into tight lumps that do not contain sugar, water, and fat molecules.