red velvet cake ingredient preference

Brittany Williams INSY 7300 Final Project Report Red Velvet Cake

December 5, 2014

Introduction Background Growing up, I always helped my mother as she baked homemade cakes for holidays. Once I turned 12, I became responsible for baking the cakes in my family. The cakes I am known for are carrot cake, pound cake, red velvet cake, and German chocolate cake. Through my experiences, Ive learned there are different perceptions on the Southern delicacy that is red velvet cake. Some think it is simply a chocolate cake dyed red. Others know that while a hint of chocolate is included, there are also flavors that come from the buttermilk and vinegar to create a distinct flavor. People that have been unsuccessful at creating a true red velvet cake have mentioned that the cake is dry. When made correctly, the red velvet cake is far from dry. Based on the theories and misconceptions of what a red velvet cake is, this experiment was designed to determine the most preferred red velvet cake, based on amounts and types of ingredients, among a general population. The experiment took place over Thanksgiving break. Factors The red velvet cake is a creamed cake. According to the Baking Industry Research Trust (2011), creamed cakes are rich and soft with a fairly close, even grain and soft crumb. In this method, the sugar and shortening fat are blended together first and then creamed by more mixing. During creaming, small air cells are formed and then incorporated into the mix, making it larger in volume and softer in consistency. The temperature of the shortening or fat controls the time needed for proper creaming. The ideal temperature is 21C for the fat. If it is too cold shortening is not plastic enough to incorporate quickly and hold air cells, while fats that are too warm will not be able to hold as much air, nor give as much volume because they are soft and cannot tolerate the friction of the machine and constant mixing. Cream sugar and shortening at a medium speed until soft and light as high speed mixing tends to destroy or reduce the number of air cells that are formed. During the second stage, add eggs in several portions. According to the American Egg Board (2013), some recipes specify that the eggs or egg whites be at room temperature when added. However, for recipes that don't specify room temperature, use eggs straight from the refrigerator. In the case of cheesecakes and other batters with a high fat content, adding cold eggs could re-harden the fat, making the batter appear curdled or lumpy, possibly affecting the texture of the baked product. To avoid this, remove the eggs from the refrigerator about 30 minutes before use, or put them in a bowl of warm water while assembling the other ingredients. Recipes that involve beating eggs or egg whites, with or without sugar, into a stable foam souffls, meringues, angel and sponge cakes also specify room temperature eggs. That's because eggs whip up to a greater volume when they've had a chance to warm up a bit, 20 to 30 minutes. Because it's easiest


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to separate whites from yolks cleanly when they are refrigerator-cold, this should be done when starting the recipe. Then let the whites stand at room temperature while you prepare the baking pan, equipment and other ingredients. Other factors affect the perception of a cake. These include oven temperature, cooking time, pan placement, the finish of the pan, and the accuracy of the measurement tools. Additionally, the subjects established preference may affect the score. Some people may already prefer a chocolaty taste in a red velvet cake. Lurking or confounding factors include the temperature of the butter, the mixing intensity, and the mixing time. An interaction between fat temperature and the fat-sugar ratio had a notable influence and size of sugar particles had a slight influence on cake firmness. Mixing intensity is a factor that affected cake moisture content significantly (Lahtinen, Levola, Jouppila, & Salovaara, 1998). Experimental Design The experimental design is three-factor full factorial with all design factors at 2 levels. The amount of cocoa (affecting the flavor), the temperature of eggs (room temperature or cold), and the type of fat used will be tested as the independent variables. The dependent variable is the overall preference, including appearance, texture, and taste. The null hypothesis is that the difference in factors will not have an effect on the response variable. The alternative hypothesis is that the difference in factors will have an effect on the response variable. The experiment assignment was designed using Minitab. Methodology Recipe The following recipe makes one 2-layer cake. It mentions both levels of each factor. Each treatment was made under identical conditions. Table 1. Experiment Set-up

Butter (-) Oil (+) 2 tsp cocoa (-) 2 tbsp cocoa (+) 2 tsp cocoa (-) 2 tbsp cocoa (+)

Room temperature eggs (+) Half-layer 1 Half-layer 2 Half-layer 5 Half-layer 6 Cold eggs (-) Half-layer 3 Half-layer 4 Half-layer 6 Half-layer 8

1 cup oil or 1 stick butter 1 cups sugar 2 large eggs (one room temperature, one cold) 1 fl oz red food coloring


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cocoa (1 teaspoon or 1 tablespoon) 1 teaspoon salt 1 cup buttermilk 1 tablespoon vanilla extract 2 cups plus 5 tablespoons sifted flour 1 tablespoon vinegar 1 teaspoon baking soda Butter cake, room temperature egg - Beat together stick of butter and cup of sugar until fluffy. - Beat in one room temperature egg. Split this mixture in half.

o (Half layer 1) In one small bowl, whisk together fl. oz. food coloring and tsp. cocoa.

Add with tsp salt to butter mixture, beating until well-blended. In another small bowl, stir together cup buttermilk and 1 tsp vanilla. Add 5/8 cups flour + 1 tablespoons flour to butter mixture in batches

alternately with buttermilk mixture, beginning and ending with flour mixture and beating until batter is blended well.

In another small bowl, stir together tablespoon vinegar and tsp baking soda and gently stir into batter. Do not beat.

o (Half layer 2) In another small bowl, whisk together fl oz food coloring and tbsp. cocoa




Butter cake, cold egg - Beat together stick of butter and cup of sugar until fluffy. - Beat in one cold egg. Split this mixture in half.


Add with tsp salt to butter mixture, beating until well-blended. In another small bowl, stir together cup buttermilk and 1 tsp vanilla.


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Add 5/8 cups flour + 1 tablespoons flour to butter mixture in batches alternately with buttermilk mixture, beginning and ending with flour mixture and beating until batter is blended well.






Oil, room temperature egg - Beat together cup of oil and cup of sugar until fluffy. - Beat in one room temperature egg. Split this mixture in half.










December 5, 2014

Oil, cold egg - Beat together cup of oil and cup of sugar until fluffy. - Beat in one room temperature egg. Split this mixture in half.






Add with tsp salt to butter mixture, beating until well-blended. There will be 8 treatments, in the form of 8 separate half-cake layers. All subjects will taste each cake and score the cake on a 7-point scale, ranging from I do not like to I like a lot. As the participants rate the cakes, they were instructed to consider not only the flavor, but the appearance and the texture as well. The experiment is performed with replication. All 8 treatments will be tested by all subjects. Protocol There were 10 test subjects. Each subject receives a slice from each treatment. Therefore, 80 slices were randomly assigned to the subjects. After all cake batters were prepared, the cake layers were baked at random. Use an oven and a timer that provide extremely precise and accurate settings. Error in the equipment compromises the precision of the results. This was a single-blind experiment. Persons very familiar with the various types of red velvet cakes, and cakes in general, were recruited as tasters. It is important that they be familiar enough to detect differences in the cakes. The data were analyzed using Minitab 16. A one-way ANOVA was used to compare the means.


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Results There is nothing unusual about the normal probability plot, the histogram, or the residuals versus order plot. The plot of residuals versus fits shows some possible inequality of variance (Figure 1). The cocoa and the temperature of the eggs are main effects, having a significant effect on the preference, while the choice of fat used did not (Figure 2-5). The low level of cocoa (teaspoon) and the high level of egg temperature (room temperature) were preferred. There were no significant interactions between effects (Figure 6). Therefore, there is a difference in the means, so the null hypothesis is rejected.

Figure 1. Residual Plots for Results

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Residual Plots for Results


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Figure 2. Main Effects Plot for Results

Figure 3. Half Normal Plot of Effects

TablespoonTeaspoon

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Room TempCold

OilButter

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Half Normal Plot of the Standardized Effects(response is Results, Alpha = 0.05)


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Figure 4. Normal Plot of Effects

Figure 5. Pareto Chart of Effects

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Normal Plot of the Standardized Effects(response is Results, Alpha = 0.05)

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Pareto Chart of the Standardized Effects(response is Results, Alpha = 0.05)


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Figure 6. Interaction Plot for Results

Discussion Based on the preference of a low amount of cocoa, we can dissuade the singular notion that a red velvet cake is a chocolate cake dyed red. It is important to use a lesser amount of cocoa to make a true red velvet cake. The experiment shows that other factors are important as well, and that a strong chocolate flavor is not preferred. By using room temperature eggs, you are able to create a finer crumb, because the eggs whip better with both fats and the cake rises appropriatelyalthough both temperatures make an acceptable cake. When using cold eggs, the mixing of the eggs with the creamed ingredients is not performed efficiently. There was no indication of cake dryness negatively affecting preference scores. This may be due to the amounts of fat these recipes required. Some recipes used may use less fat, contributing to the dryness.

Room TempC old O ilButter6.0

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Egg T emperature

Fat

TeaspoonTablespoon

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ColdRoom Temp

TemperatureEgg

Interaction Plot for ResultsData Means


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Bibliography American Egg Board. (2013). Cooking Eggs - Room Temperature Eggs. Retrieved November 28, 2014, from http://www.incredibleegg.org/recipes-and-more/cooking-school/tips-techniques-know-hows/room-temperature-eggs-when-and-why Baking Industry Research Trust. (2011). Cakes Information Sheet. Retrieved November 28, 2014, from http://www.bakeinfo.co.nz/files/file/423/Bake+Info_Info_Cakes.pdf Lahtinen, S., Levola, M., Jouppila, K., & Salovaara, H. (1998). Factors Affecting Cake Firmness and Cake Moisture Content as Evaluated by Response Surface Methodology. Cereal Chemistry , 75 (4), 547-550.


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Appendix - Factorial Fit: Results versus Cocoa, Egg Temperature, Fat Estimated Effects and Coefficients for Results (coded units) Term Effect Coef SE Coef T P Constant 4.066 0.1120 36.31 0.000 Cocoa -2.269 -1.134 0.1120 -10.13 0.000 Egg Temperature 1.156 0.578 0.1120 5.16 0.000 Fat 0.081 0.041 0.1120 0.36 0.718 Cocoa*Egg Temperature -0.369 -0.184 0.1120 -1.65 0.104 Cocoa*Fat -0.094 -0.047 0.1120 -0.42 0.677 Egg Temperature*Fat 0.206 0.103 0.1120 0.92 0.360 Cocoa*Egg Temperature*Fat -0.094 -0.047 0.1120 -0.42 0.677 S = 1.00160 PRESS = 89.1744 R-Sq = 64.93% R-Sq(pred) = 56.70% R-Sq(adj) = 61.52% Analysis of Variance for Results (coded units) Source DF Seq SS Adj SS Adj MS F P Main Effects 3 129.815 129.815 43.272 43.13 0.000 Cocoa 1 102.945 102.945 102.945 102.61 0.000 Egg Temperature 1 26.738 26.738 26.738 26.65 0.000 Fat 1 0.132 0.132 0.132 0.13 0.718 2-Way Interactions 3 3.746 3.746 1.249 1.24 0.300 Cocoa*Egg Temperature 1 2.720 2.720 2.720 2.71 0.104 Cocoa*Fat 1 0.176 0.176 0.176 0.18 0.677 Egg Temperature*Fat 1 0.851 0.851 0.851 0.85 0.360 3-Way Interactions 1 0.176 0.176 0.176 0.18 0.677 Cocoa*Egg Temperature*Fat 1 0.176 0.176 0.176 0.18 0.677 Residual Error 72 72.231 72.231 1.003 Pure Error 72 72.231 72.231 1.003 Total 79 205.968 Unusual Observations for Results Obs StdOrder Results Fit SE Fit Residual St Resid 4 9 2.50000 4.50000 0.31674 -2.00000 -2.10R 10 68 1.00000 3.27500 0.31674 -2.27500 -2.39R 14 15 4.00000 6.20000 0.31674 -2.20000 -2.32R 40 46 5.25000 2.47500 0.31674 2.77500 2.92R 41 58 5.50000 2.60000 0.31674 2.90000 3.05R R denotes an observation with a large standardized residual. Estimated Coefficients for Results using data in uncoded units Term Coef Constant 4.06562 Cocoa -1.13437 Egg Temperature 0.578125 Fat 0.040625 Cocoa*Egg Temperature -0.184375 Cocoa*Fat -0.046875 Egg Temperature*Fat 0.103125 Cocoa*Egg Temperature*Fat -0.046875

red velvet cake ingredient preference

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