The Effect of Using Whole Egg and Pure Egg Yolk on the Palatability of Leche Flan

Noriega, Clarice Joanne A.
AB-4L

A Scientific Paper submitted in partial fulfillment of the requirements for HNF 11
(Food Selection and Preparation)
2nd Semester A.Y 2014-2015 under the supervision of
Prof. Marie Faye Nguyen-Orca

The Effect of Using Whole Egg and Pure Egg Yolk on the Palatability of Leche Flan

ABSTRACT The effect of using whole egg and pure egg yolk on the palatability of Leche flan by cooking two batches of Leche flan with the same procedure wherein one was made using the whole egg and the other by using the pure egg yolk. The researchers evaluated the products according to their odor, appearance, taste, texture and general acceptability. Based on the observations made, it was found out that the product made by using the egg yolk as the main ingredient was rated higher in the evaluation because of its sweet, creamy and firm characteristics. On the other hand, the product made using the whole egg was observed to be smooth but not creamy and lacks the sweet characteristic taste of a leche flan. Therefore, the pure egg yolk is more appropriate to use than the whole egg in the preparation of a palatable Leche flan.

INTRODUCTION Eggs, packed with every nutrient and other factors necessary for man, are the most commonly eaten and widely used poultry product brought by nature. They are considered as nutrient-dense foods because they supply all the essential amino acids and provide several vitamins and minerals such as retinol, folic acid riboflavin, and other B-complex vitamins for humans. Additionally, the eggs are one of the few foods to naturally contain Vitamin D (Del Rosario, 2009). They play an important role in maintaining psychological functions and memory enhancement, and in preventing birth problems and cardiovascular diseases in infants and older people, respectively (Chavez, et al. 2006). Besides its role in health maintenance, the eggs also serve as the backbone of cooking, particularly baked goods. Eggs are an integral part of cookery and they can be used for purposes including binding, coating, glazing, emulsifying, clarifying, enriching other foods, and aerating. Its varied cooking properties are mainly due to its egg white and yolk content, which is, in fact, the reason why it was known as “the cement that holds the castle of cuisine together”(University of Alberta, 2011).
The whites of egg contain the protein component of the egg while the yolks contain the fats. They can have different purposes but they can work together as a team. Egg whites can be used as leavener while egg yolk can be used to add flavor and color to baked goods (Rehault, 2007). Moreover, the egg yolks are responsible for the egg’s emulsifying properties from fat and lecithin whereas the egg white is responsible for their foaming properties done through continuous beating (Nys, 2004). These characteristic properties prove that eggs are extremely useful foods in making so many different kinds of dishes or desserts, like cakes, meringues, icing, pastries, and the well-known, Leche flan.
Also known as crème caramel, Leche flan is considered as one of the top desserts in the Philippines. It is made up of eggs, either whole or yolk, and milk mixed with refined sugar and flavoring ingredients. It has a soft caramel on top that contributes to its rich and sweet taste. Leche flan is usually steamed over an open flame or stove top, and baked in a large oval pan (Chavez, et al. 2006). Since it can be prepared using either a whole egg or pure egg yolk, it is necessary to learn the effects of using the two components on the palatability of a Leche flan.
This study aims to determine the effects of using two different egg components on the preparation and palatability of Leche flan. The specific objectives are: 1. to identify the effects of using pure egg yolk in comparison to whole eggs in the preparation of Leche flan in terms of odor, texture, taste, appearance and flavor 2. to describe and explain the differences in the texture, appearance and flavor of the Leche flan with regards to the egg component used

MATERIALS AND METHODS In the preparation of Leche flan, the materials used were steamer, two molders, tongs, dinner spoon and forks, can opener, whisk, aluminum foil, liquid measuring cup, solid measuring cups, measuring spoons, saucers and mixing bowls. On the other hand, eggs, evaporated milk, sugar and vanilla extract were used as ingredients. Two setups were done to achieve the main purpose of the experiment. Throughout the whole process, the eggs served as the variable while the other materials and ingredients such as milk, sugar and flavoring were held constant. In the first setup, the whole egg was used and the pure egg yolk was used in the second setup. The first step in preparing the Leche flan is to caramelize the sugar to be used as a soft sweetener placed on top. Two tablespoons of white sugar were placed in each molder, and was heated above the flame until a smooth golden brown caramel developed. Meanwhile, the first setup was prepared by first beating the whole eggs and mixing the beaten eggs with the other ingredients: ½ cup sugar, evaporated milk in a mixing bowl. They were mixed carefully to prevent bubbles and foams from forming. The same procedure was done on the second setup but instead of whole eggs, the pure egg yolks were used. After that, both mixtures were strained and added with ¼ teaspoon of vanilla extract. They were, then, poured into the molds. Lastly, the molders containing the prepared mixture were placed in the steamer for 15 minutes at simmering temperature. When the Leche flan was cooked, it was transferred to a plate by simply running a knife around the edge cover with the serving dish and turned over. The products were evaluated by the researchers in terms of odor, taste, texture, appearance and general acceptability. the results were tabulated.
RESULTS AND DISCUSSION Table 1 shows that the variations in the egg components used resulted to a difference in the palatability of the leche flan in terms of texture, appearance and flavor. Pure egg yolk had a firm but tender and smooth texture whereas the use of whole eggs resulted to a firm but stiffer and not that smooth texture. Meanwhile, it can be observed in Figure 1 that the Leche flan made using pure egg yolk turned out as golden yellow brown while the lighter golden yellow brown color of the Leche flan made with whole eggs can be seen in Figure 2. The product using whole eggs appeared to be less creamy as shown by its gelatin-like appearance. Moreover, the egg yolk product was more flavorful than that of the whole eggs.
These differences can be attributed to the characteristic properties of the egg components used. The yolks exhibit emulsifying properties from the fat and lecithin contained in them which brings the water and fat phases together and makes the recipe creamier and smoother in texture (Merano, 2010). On the other hand, the whites of the egg accounts for most of the egg’s liquid weight, 67%, which is why the Leche flan was not that creamy (Moore, 2013). The difference in coagulation or cooking temperature of the two components can also affect the texture of the finished product. Since egg yolks have a higher coagulation temperature of 65°C (Chavez, et al. 2006), the Leche flan made with pure egg yolk is smoother, firmer and more tender because the egg proteins were given more time to unfold, gelify and solidify properly. To account for the difference in appearance, the color of the Leche flan made with whole eggs was lighter because of the combination of the white color of the coagulated egg white and the yellow color of the yolk. On the other hand, the egg yolk did not change in color during coagulation so it retained its bright and rich yellow color (Lowe, 1997). The Leche flan made with pure egg yolk was more flavorful compared to the one made using whole eggs because the yolk has a greater fat content compared to the egg white (Chavez, et al. 2006).
Table 1. Comparison of the Leche flan made from pure egg yolk and whole eggs in terms of texture, appearance and flavor | PURE EGG YOLK | WHOLE EGGS | TEXTURE | Firm but tender | * | | Firm but stiffer | | * | Smooth | * | | Not that smooth | | * | APPEARANCE | Golden yellow brown | * | | Lighter golden yellow brown | | * | FLAVOR | Pleasantly sweet and flavorful | * | | Pleasantly sweet and less flavorful | | * |

Figure 1. Leche flan made using pure egg yolk

Figure 2. Leche flan made using whole eggs

SUMMARY AND CONCLUSION The effect of using pure egg yolk and whole eggs on the palatability of the leche flan was determined. Two setups were prepared: the one using pure egg yolks and the other, using whole eggs. The same procedure was used in both setups while keeping the eggs used as the variable and the other ingredients held constant. When they were cooked, the finished products were evaluated by the researchers according to texture, appearance and flavor. Results showed that the use of two different egg components in the preparation of the leche flan greatly differed in terms of texture, appearance and flavor – with the product made using pure egg yolk having more favorable characteristics. These differences can be attributed to the properties, composition, color and coagulation or cooking temperature of the egg yolk and egg white. External factors could have influenced the cooking process so the researcher recommends that further experiments be done to identify these factors and determine ways on how to avoid them. Because the favorable characteristics that were observed by the researchers were parallel to the ideal character of a good leche flan – fine, smooth texture,firm but tender, golden brown, sweet, flavorful and not porous, it is concluded that the pure egg yolk is more efficient, therefore, more preferable to use than whole eggs in making a Leche flan.

LITERATURE CITED
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