Agriculture Reference
In-Depth Information
white. When you are learning to candle, you will find it helpful to break and observe any
eggs you are in doubt about.
2. Identifying cracks: Cracked eggs will appear to have a white line somewhere on the shell.
These cracks will open if you apply slight pressure to the shell. Remove cracked eggs and
consume them as soon as possible or discard.
3. USDA Grade Standard: Use the specifications given in the table below to determine the
grade of an egg by candling. Consider air cell depth, yolk outline, and albumen quality.
• Air cell depth: The depth of the air cell is the distance from its top to its bottom when the
egg is held with the air cell up (see figure 2). In a fresh egg, the air cell is small, not
more than
1
/
8
inch deep. As the egg ages, evaporation takes place, the air cell be-
comes larger, and the egg is downgraded.
Figure 2. Measuring air cell depth
• Yolk: A rather dense layer of albumen or white will surround the yolk of a fresh, high-
quality egg. Therefore, it moves only slightly away from the center of the egg when it is
twirled before the candler. Because of this, yolk outline is only slightly defined in the
highest quality eggs. As the albumen thins, the yolk tends to move more freely and
closer to the shell. A more visible yolk when candled indicates a lower quality egg.
• White or albumen: The character and condition of the white or albumen is indicated
largely by the behavior of the yolk of the egg when the egg is candled. If the yolk retains
its position in the center when the egg is twirled, the white is usually firm and thick.
