they have greater food value. These opinions do not have any basis in fact, but it is
recognized that brown eggs are more difficult to classify as to interior quality than are
white eggs. It is also more difficult to detect small blood spots in brown eggs. Then,
too, consumer preference is an important factor in marketing.
3-10. CLASSIFICATION OF INTERIOR QUALITY
Classification of interior quality of eggs, unlike some of the exterior qualities,
cannot be determined by looking at the eggs as they lie on the trays. Eggs must be
candled in order to determine the interior qualities. The interior qualities described
below include the air cell, the yolk, and the white of the egg. However, before we
discuss the interior quality factors, we will discuss the candling operation.
3-11. HAND CANDLING TECHNIQUE
Because the modern trend in egg production is towards large, highly specialized
flocks, hand candling is used very little in present commercial grading operations.
Automated equipment and mass scanning devices have practically replaced these
manual operations since the high-quality egg produced under this system lends itself to
the use of machine mass candling equipment to detect checks, irregular shells, meat
and blood spots, and loss eggs. However, hand candling is still an excellent method for
teaching and demonstrating quality determination and is used for spot checking and
determining accuracy in grading.
a. To determine interior quality by hand candling, you should hold two eggs in
each hand, supporting one egg by the tips of the thumb and index finger and holding the
other against the palm with the other fingers. The small ends of the eggs should point
toward the palm of the hand (figure 3-3). After you have candled one egg in the hand,
shift it back in a rotating motion to the palm of the hand and bring the second egg into
candling position. View the eggs alternately before the light.
b. First, examine the uppermost egg in the right hand, then the uppermost egg
in the left hand. Repeat this procedure after you have shifted the position of the eggs in
each hand. After you have candled the first egg and dropped your hand slightly back
and downward, relax the third and fourth fingers and let the uncandled egg roll
c. Use your thumb, index, and second fingers at the same time to guide the
candled egg into the palm of your hand. With the third and little fingers, then roll the
uncandled egg into candling position between the thumb and index finger; meanwhile
your little finger (fourth) and third finger hold the candled egg in your palm. Change the
position of the eggs in one hand while you are candling one of the eggs held in the other