Egg Quality Standards

The Egg Products Inspection Act of 1970 in the United States requires that all eggs moving in interstate commerce be graded for size and quality.[2,3] Cracked or dirty eggs may be sold directly to consumers only on the farm or at an authorized processing plant. Loss eggs (inedible eggs) such as leakers (broken shell and broken membranes), eggs with blood and meat spots, rots, or eggs with developed embryos may not be used for human consumption, but may be used in pet foods. Shell eggs for intrastate commerce are not regulated by the USDA unless they are part of the USDA's shield program, which is voluntary. Most states, however, have egg-grading laws or regulations very similar or identical to those of the USDA. The U.S. egg weight classes for consumers are shown in Table 1. The table shows that the minimum weight must be achieved for 12-egg cartons as well as for 30-dozen cases.

The USDA standards for quality of individual shell eggs are shown in Table 2. The quality of shell eggs is judged by external appearance and by internal appearance, as seen by candling.

The quality of shell eggs begins to decline immediately after the egg is laid. Water loss from the egg causes an increase in the size of the air cell. The dissipation of carbon dioxide migration from the egg results in an increase in albumen pH and a decrease in vitelline membrane strength. Today, supermarkets sell mostly AA shell eggs. However, as it is not mandatory for producers to participate in the USDA program, their product does not have to show the quality standard and USDA shield. Products that do not have these are seen more in discount stores.

In the United States, shell egg shelf life is 30 days from the packaging date. At 30 days, if retested, all eggs will receive much lower grades. Rapid cooling of shell eggs followed by refrigeration at 41 °F to 45°F has been found to dramatically extend shell egg quality. By U.S. law, eggs should be stored and transported at a minimum temperature of 45°F. European Union countries and their followers

Table 1 United States standards for quality of shell eggsa

Quality factor

AA Quality

A Quality

B Quality

Shell

Clean

Clean

Clean to slightly stainedb

Unbroken

Unbroken

Unbroken

Practically normal

Practically normal

Abnormal

Air cell

1/8 in. or less in depth

3/16 in. or less in depth

Over 3/16 in. in depth

Unlimited movement

Unlimited movement

Unlimited movement

and free or bubbly

and free or bubbly

and free or bubbly

White

Clear

Clear

Weak and watery

Firm

Reasonably firm

Small blood and meat

spots presentc

Yolk

Outline slightly defined

Outline fairly well defined

Outline plainly visible

Practically free from defects

Practically free from defects

Enlarged and flattened

Clearly visible germ

development, but not blood

Other serious defects

aFor eggs with dirty or broken shells, the standards of quality provide for two additional qualities:

1. Dirty, unbroken (dirt or foreign material adheres, prominent stains, moderate stained areas in excess of B quality).

2. Broken or cracked shell, membranes intact, not leaking. (Leaker has broken or cracked shell and membranes; contents are leaking or free to leak.) bModerately stained areas permitted (1/32 of surface if localized, or 1/16 if scattered).

cIf they are small (aggregating not more than 1/8 in. in diameter). From Ref. 4.

aFor eggs with dirty or broken shells, the standards of quality provide for two additional qualities:

1. Dirty, unbroken (dirt or foreign material adheres, prominent stains, moderate stained areas in excess of B quality).

2. Broken or cracked shell, membranes intact, not leaking. (Leaker has broken or cracked shell and membranes; contents are leaking or free to leak.) bModerately stained areas permitted (1/32 of surface if localized, or 1/16 if scattered).

cIf they are small (aggregating not more than 1/8 in. in diameter). From Ref. 4.

do not require egg refrigeration, but specify a shorter expiration date.

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