Egg Structure and Composition PDF

H  In general, an egg is composed of the SHELL WHITE YOLK Introduction: Since the beginning of time, egg has been a source of protein. Egg comes from various Brown and white eggs birds such as goose, duck, ostrich, and quail. But most used in culinary is the chicken’s egg....

H  In general, an egg is composed of the SHELL WHITE YOLK Introduction: Since the beginning of time, egg has been a source of protein. Egg comes from various Brown and white eggs birds such as goose, duck, ostrich, and quail. But most used in culinary is the chicken’s egg. This lesson will serve as your vehicle in acquiring knowledge, skills and values needed in preparing variety of egg dishes. It deals with the basic principles of Egg Cookery preparation and presentation. Eggs are a staple part of the diet of millions of people around the world, mainly because they are inexpensive, readily available and easy to prepare. The fact that they are exceptionally nutritious is another reason why eggs are popular as staple food.  Eggs have been consumed in different parts of the world for thousand of years. Their versatility and unique flavors have led to the creation of thousands of delicious dishes that sate the appetite. Indeed, eggs are some of the most healthful and nutritious food. These are packed with numerous vitamins, minerals, and other nutrients that are essential to overall health and wellbeing. The many healthful benefits of eggs have been made them even more popular options for breakfast, lunch, dinner, and even snacks.  PHYSICAL STRUCTURE AND COMPOSITION OF EGGS The structure of an egg is designed to support the development of the embryo to protect the embryo from physical trauma and microbial contamination. Content Standard Demonstrate understanding of the basic concepts and underlying theories on the preparation and cooking of egg dishes. Performance Standard Prepare a variety of egg dishes Expectations: At the end of the lesson, you should be able to: 1. Identify the different parts of an egg 2. Discuss the functions of each part What is an Egg? An egg is defined as the oval reproductive body that is laid by various types of animals, including birds and fowl that are used by humans as food. In cooking, chicken eggs are the most commonly used, but duck, goose, quail and ostrich eggs are often used to make different dishes.  In cookery, refers to poultry or fowl products. The versatility of egg is evident in its presence in numerous food items. Eggs maybe eaten cooked in its, shell, fried or poached or maybe combined with other ingredients to produce another dish. In baking, egg acts both as emulsifier and leavener.  Bloom-. Also known as the cuticle, bloom is the natural coating or covering on the eggshell that seals the eggshell pores Membrane –The layer of material that covers an animal egg cell. Permeable- having pores or openings that permit liquids or gases to pass through (of a material or membrane) allowing liquids or gases to pass through it. ANATOMY OF AN EGG Shell Bumpy and grainy in texture, according to exploratorium.edu eggshell is covered with as many as 17,000 tiny pores. Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals. It is a semipermeable membrane, which means that air and moisture can pass through its pores. The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust. The egg‘s outer covering, the shell, accounts for about 9 to 12 % of its total weight depending on egg size.  The breed of the hen determines the shell color; for chickens, it can range from white to brown. Shell color has no effect on quality, flavor or nutrition. Inner and Outer Membranes Lying between the eggshell and egg white, these two transparent protein membranes provide efficient defense against bacterial invasion. If you give these layers a tug, you will find they’re surprisingly strong. They are made partly of keratin, a protein that is also in human hair. Air Cell This is the empty space between the white and shell at the large end of the egg which is barely existent in newly laid egg. When an egg is first laid, it is warm. As it cools, the contents contract and the inner shell membrane separate from the outer shell membrane to form the air cell. The air cell usually rests between the outer and inner membranes at the egg’s larger end, and it accounts for the crater you often see at the end of a hard-cooked egg. The air cell grows larger as an egg ages.  The egg white is known as the albumen, which comes from albus, the Latin word for “white.” Is the clear portion of the egg Albumen and is often referred to as egg white. It coagulates, becoming firm and opaque at temperature between 60-65C. Chalazae cords This is the ropey strands of egg white at both sides of the egg, which anchor the yolk in place in the center of the thick white. Like little anchors, they attach the yolk’s casing to the membrane lining the eggshell. The more prominent they are, the fresher the egg. Vitelline Membrane The clear casing that encloses the yolk, it is composed of proteins that separates the egg from the albumen. It is developed during the early stage of formation in the chicken’s ovary. Albumen is later developed and encased in calcium crystal to form what we know as egg. Germinal disc This is the entrance of the latebra, the channel leading to the center of the yolk. Yolk The yolk contains less water and more protein than the white, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin. The yolk is also a source of lecithin, an effective emulsifier. Yolk color ranges from just a hint of yellow to a magnificent deep orange, according to the feed and breed of the hen.  It is the yellow portion of the egg. It constitutes just over one- third of the egg and contains three-fourths of the calories, most of the minerals and vitamins and all of the fat. It solidifies at temperature between 65-70C Although the color of the yolk may vary depending on the hen’s feed, color does not affect the quality or nutritional content.  Eggs are sold in JUMBO, EXTRA LARGE, MEDIUM, SMALL and PEEWEE sizes as determined by weight. Food service operations generally use large eggs Nutrition Eggs contain vitamins A, D, E, K and B- complex vitamins. They are rich in minerals and contain less cholesterol In fact, American Heart Association now suggests that it is acceptable to consume up to four egg yolks per week as part of the balanced diet. Egg whites do not contain cholesterol and more often added to egg dishes such as omelets to reduce total fat content.  Related Links How eggs form in a chicken: https://www.youtube.com/watch?v=G6j13-9Pexw Eggs, how it is made: https://www.youtube.com/watch?v=g1IVTDmV35o