Eggs: Nature’s Wonder Food

Terms to Know

• Air Cell: The empty space between the white and shell at the large end of the egg.  The size of this tiny pocket of air is an indication of freshness.

• Albumen: Also known as egg white, albumen accounts for most of an egg’s liquid weight.

• Candling: The step in grading that lets the egg grader look inside the egg without breaking it to judge its quality. Today most eggs pass on rollers over high-intensity lights which make the interior of the egg visible.

Terms to Know

• Hatchery: A building equipped with machines in which fertile eggs are kept for the 21 days required to hatch chicks.

• Yolk: the yellow, inner part of the egg where the embryo will form. The yolk contains the food that will nourish the embryo as it grows.

• Grading: Classification standard for eggs determined by interior and exterior quality and designated by letters AA, A, B, and C

Terms to Know

• Germinal Disk: is a small, circular, white spot on the surface of the yellow yolk of a bird's egg.

• Chalazae: is a structure inside bird eggs. Attaches or suspends the yolk within the larger structure.

• Vitelline Membrane: the membrane that surrounds the yolk.

Terms to Know

• Shell: the hard, protective coating of the egg. It is semi-permeable; it lets gas exchange occur, but keeps other substances from entering the egg.

• Outer Membrane: the thin membrane located just inside the shell.

• Inner Membrane: the thin membrane located between the outer shell membrane and the albumin.

The Hens

• Eggs from breeding flocks are placed in incubators. After 21 days, the eggs hatch and the chicks are housed in a pullet barn (a pullet is a young hen).

• At 19 weeks of age, the hens are transferred to another barn to begin producing eggs. In Canada, hens continue to lay eggs for about 12 months.

The Hens

• Younger hens are more likely to produce double-yolked eggs than older hens. 

• In 1945, the average hen laid 151 eggs per year. Today, with better nutrition, improved housing and lighting programs, the average hen lays approximately 300 eggs per year—that's one egg every 1½ days. 

The Hens

• The most common laying hen in Canada is the White Leghorn, a small bird that lays white eggs. Another common breed, the Rhode Island Red, lays brown eggs.

• A hen's feed determines the color of the egg yolk. A hen that eats a wheat-based diet (more common in the western provinces) produces a pale yellow yolk, while a hen consuming a corn- or alfalfa-based diet produces a yolk that is dark yellow.

The Hens

• As a hen ages, the size of her eggs increase. The younger the hen, the smaller the egg.

• Most of the eggs produced in North America come from hens housed in cages. Birds have ready access to the feed troughs directly in front of their cages, and water is easily accessible from each cage.

The Barns

• The cage system is the preferred housing system for today's egg production and ensures the highest possible food safety and egg quality standards.

• Cage systems also help keep the eggs safe from the bacteria that can be found in chicken manure. They are designed to allow manure to fall outside of the cage, away from the hens and from the eggs.

The Barns

• Other housing systems such as free-range or free-run are also available at some farms. 

• Free-run refers to a production system where hens can roam inside a laying barn.

• A free-range system is similar to a free-run system, except the hens have access to the outdoors in a fenced-off pasture.

Egg and Bird Safety

• Providing good care for farm animals is the top priority of Canada's egg farmers.

• Farmers will often work with poultry specialists and veterinarians to design flock health. The hens are checked daily to ensure that they are healthy, and are eating and drinking as needed. 

Egg and Bird Safety

• Egg farmers adhere to the national guidelines of the ”Start Clean - Stay Clean” program.

• This is a national producer program to ensure that farmers are producing safe, clean, high-quality eggs. Egg farms are inspected regularly to ensure that farmers are following program requirements.

Start Clean-Stay Clean Program

• Here are some of the directives, guidelines and objectives of this national program:

1) Take care of the farm animals.2) Buying young birds and feed from

suppliers with disease prevention programs.

3) Setting up restricted areas on a farm.4) Special cleaning procedures (bio-security)5) Monitoring flock health.

Start Clean-Stay Clean Program (cont…)

6) Removing manure regularly.7) Pressure washing and sanitizing the

inside of laying barns.8) Monitoring and maintaining proper

ventilation, and temperature and humidity.9) Frequent egg collection, and the speedy

removal of dirty or cracked eggs.10) Storing eggs in a cool room at 10-13

degrees Celsius.

Egg Natural Defense

• Eggs have three lines of natural defense from bacteria. They are:

1) An exterior shell.

2) Two interior membranes… one is on the inside of the shell and the other covers the white of the egg.

3) The egg white contains antimicrobial properties that fight bacterial growth.

The Egg

Now let’s take a look at what happens to the eggs once they’re laid.

1. The eggs are packed onto clean flats on the farm.

2. The flats are stacked onto pallets and then wrapped in plastic.

3. The pallets are then stored in a room at a temperature of 10-13◦C.

Storing the Eggs

Grading the Eggs

• A truck picks up the eggs from the farm and delivers them to the grading station.

At the Station

What happens at the grading station?

1) The eggs are washed.

What happens next?

2) The eggs are inspected in a ‘candling’ process.

The eggs are placed on a conveyor belt and strips of light are shot through the eggs so any imperfections or cracks can be seen.

Inspecting the Eggs

3) After the eggs have been inspected, they are graded.

Grading the Eggs

Eggs are graded into 3 categories.

Grade A:

• For use at home.

• These eggs have a clean, uncracked shell with a normal shape.

• Sold directly to consumers.

Grading the Eggs

Grade B:

• Mostly sold to commercial businesses for use in baking or for processing.

• The shell is not cracked but may have stains or soiled patches.

Grading the Eggs

Grade C:

• Sold to commercial processors only.

• Shell may be cracked and 1/3 of the shell may be stained.

4) Eggs are Weighed

Weighing the eggs occurs after grading.There are 6 categories of weighing. PEEWEE (Less than 42g)SMALL (At least 42g)MEDIUM (At least 49g)LARGE (At least 56g)X-LARGE (63g or more)JUMBO (70g or more)

Last Step….

The final step before the eggs hit the grocery store is—putting the eggs into cartons.

5) Packing the eggs to sell at the grocery store.

The Grocery Store

• As soon as the eggs leave the farm, they are rushed to grocery stores in refrigerated trucks.

• The cartons of eggs are delivered to the stores where they are placed into a refrigerated egg case.

• The temperature in these cases are 4 degrees Celsius or less.

• If the egg cases are full, the eggs will be stored in a cold storage area.

Buying Eggs at the Store

• When buying eggs in the store, you should check for the following to ensure your eggs are the best quality possible:

1) Official Canada Grade stamp (certifies that the egg has been classified by their quality).

2) Best Before Date (set for 28-42 days after grading). Lets you know how long the eggs will keep their grade A quality.

3) Nutritional facts table (mandatory on most food packaging).

Specialty Eggs

• Omega 3 Eggs: Eggs from hens that get 10-20% more Flaxseed in their diet making their eggs rich in Omega 3 fats.

• Vitamin Enriched Eggs: These eggs come from hens fed diets high in certain vitamins such as Vitamins E, B, B12, and folate).

• Organic Eggs: Eggs that are from hens fed certified organic grains. These eggs have the same nutrient content as normal eggs.

Specialty Eggs (continued)

• Vegetarian Eggs: The eggs of hens fed a diet containing only ingredients of plant origin.

• Premium Quality Eggs: These eggs are from specifically selected young hens at the peak of their laying cycle. These eggs often have thicker shells and whites.

• Free Run Eggs: From hens that are able to run on the floor of the barn.

• Free Range Eggs: From hens that are able to move on the floor of the barn as well as outdoors.

Handling Eggs at Home

• Bacteria love warm temperatures so eggs should be immediately refrigerated at home.

• You should keep eggs in the carton to help them from absorbing odors and flavors from other foods.

• The carton also protects the egg from breaking and makes the best before date visible.

• Eggs should be stored in the main part of the fridge and not on the door (due to temperature fluctuations around the door).

Cooking and Handling Eggs

• When cooking with eggs, it is important to follow the following handling tips:

1) Clean any areas, surfaces, and utensils that come in contact with raw egg.

2) Make sure the eggs are chilled well before using.

3) Keep raw eggs separate from other food…never cross contaminate.

4) Cook the egg fully and serve it immediately.

Breaking Stations

• Eggs that do not meet the standards for selling in the grocery store (cracks, stains, misshapen, etc…) are sent to breaking stations.

• Here the eggs are broken by a very fast machine, then separated into yolks and whites or broken as whole eggs.

• If the eggs are divided they are put into separate containers.

Breaking Stations (continued)

• After breaking, the liquid eggs are pasteurized (heated to a high temperature to kill any bacteria), then stored as liquid or dried eggs.

• The processed eggs are then used to make some foods as well as non food items.

• The shells are then crushed and put into hog or chicken feed for added calcium.

Nutrition of Eggs

• Vitamin A: Helps keep skin and eye tissue healthy. Promotes night vision.

• Vitamin D: Helps keep bones and teeth strong.

• Vitamin E: Protects your cells from the damaging by products pr oxidants that form in the body.

• B12 and Folate: Helps manufacture red blood cells.

Nutrition of Eggs (continued)

• Riboflavin: Helps keep the tissues on the body healthy by promoting oxygen absorption.

• Iron: Carries oxygen to your cells and keeps the blood healthy.

• Niacin: Helps release energy and promote health nerve function.

• Choline: Promotes healthy brain development and memory (one egg provides half of the daily requirement).

• Lutein and Zeaxanthin: Helps maintain good vision and prevents eye disease such as cataracts and degeneration.

Parts of an Egg

The Incubation Period

•

End of Section Questions

• 1) How are most hens housed in Canadian barns? What are three benefits of this housing system?

• 2) What is the Start Clean-Stay Clean Program? List five goals or objectives of this program.

• 3) What are the three natural defenses of eggs?• 4) When buying eggs in the store, what are three things

you should check for?• 5) List and explain five specialty egg types.• 6) What are the four handling and cooking tips for eggs?• 7) List and explain the benefits of at least five of the

main vitamins and nutrients found in eggs.