IDEAL PRACTICES / METHOD OF COMMERCIAL TABLE EGG HANDLING, GRADING & PRESERVATION
by-DR. RAJESH KUMAR SINGH, (LIVESTOCK & POULTRY CONSULTANT), JAMSHEDPUR
JHARKHAND,INDIA 9431309542, rajeshsinghvet@gmail.com
The quality of an egg is governed by both external and internal factors. The external factors include size, shape and conditions ofthe shell whereas internal factors include air cell size, conditions of albumen and yolk. All these factors are important for consumer acceptance. The quality of egg can be evaluated by egg candling procedures. It helps in detecting cracked and abnormal eggs such as egg with blood spot. The Egg Handling, Grading, Preservation, Packaging and eggs are graded for marketing purposes. They can be graded according to size, Storage weight and other quality factors. Freshly laid eggs are of good quality but as aging proceeds. various physical and chemical changes sets in resulting in deterioration of egg. To enhance the shelf life of an egg various preservation methods can be used. Proper packaging and storage system are also required for maintaining the quality of egg.
EGG HANDLING—
One must know how to handle the egg at different stages – froin the production to consumption. It is not possible to maintain high quality of egg without proper handling. I After collection of eggs from layer house following steps should be followed:
* Eggs should be collected in coated wire baskets or plastic container to facilitate cleaning and disinfection. Metal containers are not generally used to avoid rust.
*Eggs should not be stacked too high to avoid breakage. These should be washed properly as soon as possible aiter col lection. This reduces the chai~ces of contamination and loss of interior qualities. For cleaning of dirty eggs, mild detergent call be used.
* Eggs should be washed with little warmer water so that egg contents swell and push the dirt away from the pores.
*Eggs should not be cooled before cleaning because egg shell may contract and pull any contaminaiit from the surface to pores during cooling. After washing, eggs are cooled and dried. *Eggs should be stored as large end up. At least 75% relative humidity and temperature below the ambient temperahu-e should be maintained in the storage for highest quality eggs.
* Eggs should not be kept in a place close to orlions, potatoes, apples. kerosene or strong odour of any kind because eggs absorb odour during storage.
Proper handling during transport and storage is very important wlrich will be discussed later in this unit
EGG GRADING———
The commercial method of determining the interior and exterior quality of a shell egg
is by candling. This method involves: (i) holding the egg before a suitable light at about elbow level with the air cell upward as shown in Fig 3.1, (ii) giving a quick twist in order to start the contents whirling. This makes the interior of the egg visible and the exterior of the egg more visible. This helps to see the condition of the shell, the size ofthe air cell and whether the yolk is well centered (a sign that the white is thick, as it holds the yolk in position). ‘hus it makes air cell, egg white, yolk, blood spots and other contents easier to distinguish. During candling, the shell is examined for porosity, cracks and cleanliness. Ifthere is any white line on the shell, then there is a cracked egg. Cracked eggs should not be stored but consumed as soon as possible or discarded. The size of air cell should be checked. The distance between top and bottom of the air cell, when the egg is held with air cell up, is measured as depth ofthe air cell. In a fresh egg, air cell is small and not more than 1 /St” inch deep. With the aging of the egg, air cell becomes larger due to evaporation and the egg is considered as low grade. The condition of albumen, its viscosity, presence of meat and blood spot is also visualized. Commercially, candling by flush candling and grading according to sizelweight are done together followed by oil spraying on shell eggs. Grading generally involves the sorting of products to quality, size, weight and other factor that determine the relative value of the product.
Advantages of grading and standardization: ———–
Provide uniform categories – is of economic importance to interstate and foreign trade.
Give assurance of quality.
Personal inspection is not necessary.
A basis for settling disputes involving quality.
Quality Factors in Grading of Egg———–
The various interior and exterior quality factors used in grading eggs are as follows:
- Interior quality
(a) Condition of the yolk: Visibility of yolk, ease of its movement and shape are examined. In fresh egg, yolk is in the centre of the egg compared to old eggs. Presence of any blood spot or meat spot is also examined.
(b) Condition of the albumen: Albumen should be thick and firm in fresh eggs.
(c) Condition of the air cell: Air cell size is small in fresh egg and it increases with time of storage.
- Exterior quality
(a) Soundness of the shell: Shell may be broken, dented or may have cracks.
(b) Cleanliness of the shell: It has consumer appeal. Shell should be free from any visible dirt.
(c) Size: Eggs may be ofjumbo size, extra large, large, medium, small, peewee size.
(d) Shape and texture of the shell: Visual inspection reveals mis-shaped, rough or thin- shelled eggs.
(e) Colour of the shell: It has consumer’s preference. Brown shell are preferred than white shell but it has no significance in quality. Shell colow may vary from white to brown, depending upon the breed of the hen.
On the basis of above factors, Indian and USDA standards for quality of eggs are given in Table 3.1 and 3.2 respectively. Popular grading system in India is as per the Table Egg Grading and Marking Rules, 1968. Grades according to this rule are given in table 3.1 . Egg Handling, Grading, Preservation, Packaging and Storage Generally egg from pullet flock is ofbetter grade compared to that of aged birds.
Indian Standards for Table Eggs———-
Grading of Eggs
Grading is the sorting out of eggs into different categories according to the interior quality and the individual weight of an egg. The practice brings more profit for the salesman.
Based on the quality of eggs, two grades and according to size, four classes have been adopted. Grading for internal quality is done by candling while for noting the weight of an individual egg there are various types of automatic devices in the market. The Agricultural Produce (Grading and Marking eggs) Rules, 1937, require that the mark on each egg shall consist of the word `AGMARK’ together with the grade designation placed centrally in a circle of not less than ½ inch diameter by means of a rubber stamp.
Agmark standards for marketable eggs
| Grade | Weight (g) |
Shell | Air cell | White | Yolk |
| A-Extra large A-Large A-Medium A-Small |
60 & above 53-59 45-52 38-44 |
Clean,unbroken And sound, shape normal |
Up to 4 mm in depth practically regular or better |
Clear reasonably firm |
Fairlywell centred, practically free from defects outline indistinct. |
| B-Extra large B-Large B-Medium B-Small |
60 & above 53-59 45-52 38-44 |
Clean to moderately, stained, sound and slightly abnormal |
8 mm in depth, may be free and slightly bubbly |
Clear,may be slightly weak |
May be slightly offcentered,outline slightly visible |
Standards for Weight Classification of Shell Eggs
| S N. |
Size | Weight per egg (gms) |
Weight per dozen eggs (gms) |
| 1 | Extra large | 60 and above | 715 & above |
| 2 | Large | 53 to 59 | 631 to 714 |
| 3 | Medium | 46 to 52 | 535 to 630 |
| 4 | Small | 38 to 44 | 456 to 534 |
Methods of egg preservation———-
There are different methods for preserving the surplus eggs. Following are commercial methods of preservation.
- Cold storage (5 to 8 months)
The temperature of an egg-storage room should be maintained at +0.50C to –0.50C (310 to 330F) being the temperature usually preferred. A relative humidity of 75 to 85 per cent is necessary. Too much humidity favours the formation of moulds.
- Frozen eggs
The freezing of the internal contents of eggs is now a common method of preservation specially in developed countries. The eggs are first candled and when they are broken out, the smell and appearance of the contents are noted for any possible defects. The yolk and the white may be frozen separately with addition of 5% glycerine. The egg contents are then freezed in 30-40 lb., tin at a low temperature range of 100F to 300F below zero. The contents are then kept at a low temperature until required for use. In case the storage temperature is zero or below, the frozen eggs may be stored with little or no loss of flavour for 12 months or longer.
- Dried eggs
Egg drying is now largely practised in place of freezing. Although the process is more expensive but there is a considerable saving in transport and less need for cold storage. The egg contents are dried at a temperature of 1600F and stored less than 500F to convert white, yolk or the whole egg into a fine powder. The whole egg is of use for bakery products, the yolk for flours and the albumen for confectionaries.
