Eggs are an amazing source of nutrition and have been eaten by humans for hundreds of years. Although eggs can come from a variety of sources including chickens, ducks, and quails but for the purpose of this information I’ll be referring to chicken eggs.
Eggs are made up of three main parts. The shell and its membranes, the yolk and the white or albumen. The shell is around 10% of the total weight, the white is around 59% and the yolk 31%. Eggs are currently sold most commonly by the dozen in packs of different weights in medium, large, extra large and jumbo sizes.
Common weights In Australia for a dozen eggs are –
Medium : 500 grams
Large: 600 grams
Extra Large : 700 grams
Jumbo: 800 grams
Approximate Individual egg weights are –
Large: 52 grams
Extra Large: 60 grams
Jumbo: 68 grams
Extra Jumbo: 73 grams
Eggs are produced in Australia from hens kept in either a cage, barn or free range environment. Each method of egg farming has its pros and cons, but at the end of the day, consumers make a choice which type of farming they are going to support by purchasing their favourite egg products. Organic and free range eggs are becoming more popular and are readily available at your local supermarket at a higher cost than their caged counterparts. I’m not going to go into the ethical or environmental details between each method of egg manufacture, instead I’m going to focus on the function of Eggs in food and beverage applications. If you would like to do further research into the methods of Egg manufacturing, there are some links at the bottom of this page if you would like more information.
Nutrition of Eggs – Eggs offer a total package of nutrition for consumers. By consuming 1 whole large egg, you will receive around 6g of high quality protein, with around 5.5g of this located in the white or Albumen of the egg. Egg protein contains all 9 essential amino acids necessary for the body to digest and utilise this protein efficiently which is why Eggs are such an excellent source of protein.
One whole large eggs contain around 5g of Fat located in the yolk. The fat component is made up of polyunsaturated, monounsaturated fats and a small amount of saturated fat. One egg contains around 0.6g of Carbohydrates and over 11 vitamins and minerals essential to good health. They really are the complete package.
For more Nutritional information please see this link to the Pace Farms website – http://www.pacefarm.com/index.php?option=com_content&view=article&id=21&Itemid=126
Egg Nutrition Council of Australia below –
In the past there were a lot of misconceptions about the number of eggs we can safely consume per week as part of a healthy diet. There were concerns that egg consumption contributed to levels of Saturated Fat and Cholesterol in the body which then contributed to Coronary Heart Disease. Thankfully, modern research has shown that consuming up to 6 eggs per week does not increase these factors and we can safely consume whole eggs as part of a healthy diet. For more information please see the Heart Foundation website at –
Unfortunately some members of our community, especially young children can have an allergic reaction to the protein found in egg whites or the yolk. This can make life difficult as so many of our processed foods contain eggs or egg based ingredients. Eggs perform a variety of functions in processed foods and replacement of Eggs in products with other natural ingredients can be challenging as Eggs are quite unique in the functions they perform.
Eggs as an Ingredient – Eggs are used as an ingredient in a number of forms. To ensure all egg products are safe for consumption, they are pasteurised to reduce the presence of microbes and remove the pathogenic bacteria Salmonella. Egg products include –
- Fresh Liquid – Whole egg, egg white (albumen) or yolk
- Frozen – Whole egg, egg white (albumen) or yolk. These frozen products are defrosted before using. To preserve the quality and functionality of the egg during the freezing and in the finished product, egg processers typically add around 10% of salt or sugar their frozen egg products.
- Powder – Dried egg products are produced from pasteurised liquid egg that is spray dried. Products include powdered whole egg, egg white and egg yolk. These dried egg products often contain an anti-caking agent to prevent clumping. To improve the whipping ability of powdered egg white, sometimes a whipping agent is added to assist in aeration for the manufacture of Pavlova’s or meringues.
- Egg Protein – Egg protein powders are made from egg white or albumen. They are used in sports supplements as a high quality protein source.
Function of Eggs in Processed Foods – Eggs are a cheap and traditional ingredient used in across the Food Industry. As you’ll see below they perform a wide range of functions in food products.
Eggs are used in food and beverage applications for a variety of reasons including –
- Enriching or Increasing the Nutritional content of foods – As a whole food, eggs are packed full of protein, vitamins and minerals and they can be incorporated into many different recipes to increase the nutritional content of processed foods. Examples of this includes egg pasta/noodles, whole egg mayonnaise and custards.
- Leavening, Aerating and Whipping agent – During whipping and beating products containing egg white, the protein in the egg forms a fine film, entrapping the air bubbles being incorporated. The protein forms a stable foam as the protein film partially coagulates when it comes into contact with air. During further baking or heating the air bubbles expand and the protein sets fully providing a firm aerated structure to products such as sponge cake, Meringue, Pavlova’s, etc.
- Binding agents – When the proteins from egg whites are dispersed amongst other ingredients and heat is applied, the protein is coagulated forming a stable network, holding the ingredients in place. Egg whites are commonly added for this reason to recipes to assist with binding ingredients together. Applications include products such as burgers, meatballs, meat fillings, vegetable patties, bakery fillings, biscuits, crackers and confectionary products such as nougat and fondant and Surimi or fish/seafood sticks.
- Adhesion and Coating – We have all grown up with using flour, egg wash and breadcrumbs as the standard coating system for coated foods made at home. Egg white or whole egg powders can also be added to pre-dusts, batters and breadcrumb systems to improve coating coverage onto freshly coated and cooked pieces of chicken and fish. During heating the protein coagulates and forms a network that helps to stick the coating onto the food product during cooking and handling. Many processors manufacturing frozen portions of chicken or fish in can tend to avoid using egg as it’s an allergen, and instead use a range of starches, flour types and gums to improve coating adhesion.
- Thickening and Setting agent – When used in products such as custards for thickening, the egg proteins which are dispersed throughout the milk base coagulate during cooking and heating. This sets up a protein structure which thickens the custard for example pouring custard. The firmness of the resulting custard depends on the amount of egg verses milk, the amount of sugar and agitation used during the cooking process.
- For Emulsification – Lecithin, found naturally in the egg yolk has emulsification properties. The lecithin allows the yolk to disperse particles of oil, water and other ingredients in a stable matrix, keeping the oil particles apart and preventing separation of the ingredients over time. Egg yolks are traditionally used in emulsions such as whole egg mayonnaise, sauces, dressings and dips etc. for this purpose.
- Prevent Ice Crystal formation – Egg Yolks are traditionally used in sorbets and ice creams as a natural Emulsifier to minimise ice crystal formation. The Lecithin in the yolk also emulsifies the fat globules in the cream component keeping the fat and water particles small during freezing, creating a smooth mouthfeel when eating.
- Glazing and Royal Icing – Egg whites are used in Sweet and Savoury glazes and icings to coat bakery products for visual appeal and to protect them against staling. This is commonly done on decorated donuts. Royal Icing is a hard white icing made from Egg Whites and Icing sugar. It sets hard once dried and is used to make icing flowers, figurines and to decorate biscuits and cakes.
- Egg Washes – Egg wash is commonly used as the first stage of crumb coating, to bind raw pastry pieces together or as a final glaze to the outer surface of baked goods before baking. Your local bakery may apply it to the surface of breads and bakery before seeds or inclusions are added. During baking the proteins coagulate adhering seeds and inclusions onto the surface of the baked good. During baking the egg wash also undergoes the Mallard reaction, developing a golden baked colour enhancing the visual appeal of baked goods.
As you can see Eggs are used for a range of reasons in food products. If you would like to find more resources on eggs, egg manufacturing, egg nutrition and egg ingredients in processed foods please feel free to read the following links for more information. If you have any questions, please let me know on the contact form below.
Interesting Links for further reading –
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