(3) Yellow rot. In its initial stages, yellow rot (YR) is often hard to
differentiate from heavy mottling of the yolk. The vitelline membrane is often opaque
and very thick and white in places. The breaking down of the yolk membrane allows the
yolk pigment to enter the white, turning it a straw or urine color. Yellow rot may be
caused by a type of general bacterial decomposition. It is assumed to develop into a
(4) Mixed rot. Mixed rot (MR) (addled egg) occurs when the vitelline
membrane of the yolk breaks and yolk material mixes with the white. The resultant
murkiness throughout the egg can be detected before the candling light. This rot is a
generalized type of bacterial decomposition, probably caused by heterogeneous flora.
Many consider mixed rot as an intermediate stage that develops prior to black rot.
(5) Sour rot (SR). Sour rot (SR) is very difficult to detect and is especially
prevalent in eggs that have been stored. The egg has an ammonia-like odor when it is
broken out on a plate. Generally, eggs in this condition show a weak white and murky
shadow around an off-center swollen yolk. The bacteria causing sour rot belong to a
genus named Pseudomonas. These organisms produce a material which fluoresces
under ultraviolet light (back light), giving off a green sheen. The adoption of ultraviolet
light in candling has made the detection of this type of loss easier.
(6) Green whites. Eggs with green whites (GW) can be detected by an
experienced grader using a standard candling light. (This condition is difficult for an
inexperienced grader to detect.) This type of loss is also caused by the Pseudomonas
genus of bacteria. Like sour rot, eggs with green whites will fluoresce under the
ultraviolet light when broken out. Eggs with GW may or may not have a sour odor.
(7) Black rot. Black rots (BLRT) are generally opaque (with the exception of
the air cell) when viewed before the candling light. When broken, the contents have a
muddy brown appearance and give off a repulsive, putrid odor. The bacteria most
frequently causing this type of loss belong to a genus named Proteus. However, any rot
at an advanced stage may appear "black" before the candling light.
(8) Musty eggs. Musty (MSTY) eggs frequently appear clear and free from
foreign material when viewed before the candling light and can generally be detected
only by the characteristic musty odor emanating from the egg. Sources of
contamination may be a musty odor in the case or the nesting material, or the presence
of this odor on the shell itself. It is said that certain bacteria that occasionally invade the
egg give off this characteristic odor also. Since this type of loss is impossible to detect
by visual observation, it is important that the grader be able to detect the odor
emanating from the case and packing material immediately upon opening the case.