Studies the importance of factors affecting eggshell damage such as type of pack, age of laying hen and season of year.Agribusiness,

Lederer, Bruce E.

English

Research Papers in Economics

PROTECTING SHELL EGGS BETWEEN
PACKING PLANT AND SUPERMARKET
by
Bruce E. Lederer
Market Operations Research Laboratory
USDA, Beltsville, Maryland
Studies the importance of factors
affecting eggshell damage such as type
of pack, age of laying hen and season
of year.
Some of the major factors influenc-
ing shell egg quality during distribution
are the age of the laying hen, climatic
conditions, handling methods, and packag-
ing materials.
The objectives of this study were:
1. determine the rate of eggshell damage
along the distribution channel by age of
laying hen, season of year, and type of
pack (refers to the combination of master
container type and stacking pattern of
egg cartons within the container).
2. To determine whether eggs which
had checked shells when sampled at the
packing plant have a greater tendency to
become leakers by the time they reach
the supermarket than do eggs which have
sound shells at the plant.
Procedures
Research was conducted over a one
year period in three States: Alabama,
Minnesota, and Texas. Cooperation in
these States was obtained from five large
packing plants and 16 retail supermarkets
of various sizes. Outdoor temperatures
ranged from -300F to 1020Fc
The two types of master containers
tested were:
June 78/page 19
1. Corrugated paperboard case, 30-dozen
capacity, 200-pound bursting strength.
2. Wire basket, 15-dozen capacity.
The stacking pattern of the egg
cartons within the master containers was
either parallel or cross tiered. Both
stacking patterns were used in each type
of master container.
The eggs in each test shipment were
grade A or AA large and came from birds
that were from 36 to 70 weeks old, The
eggs were kept at temperatures ranging
from 55° to 75°F, with 80 percent rela-
tive humidity, and were 1-2 days old
when they were packed and graded at the
plant.
Several types of egg cartons were
used, but only one type was used for
each individual truck shipment from plant
to supermarket. In addition, all eggs
for each shipment came from the same
flock of birds.
1. Within five paperboard cases, al-
ternate tiers of egg cartons were stacked
parallel with each other. The bottom
tier of cartons was placed either across
or along the seam formed by the meeting
of the bottom inner case flaps.
2. Within the remaining five paper-
board cases, alternate tiers of cartons
were cross stacked. Again, the bottom
tier of cartons was placed either across
or along the seam.
Journal of Food Distribution Research3. Within five wire baskets, alternate
tiers of cartons were stacked parallel
with each other.
4. Within the remaining five baskets,
alternate tiers of cartons were cross
stacked.
At each checkpoint, graders in-
spected the eggs according to the stan-
dard U.S. Department of Agriculture
random sampling procedures.
Examination was for checks and
leakers only. The data presented here
are based on a total of 24 truck ship-
ments of 20 master containers each. Most
shipments were delivered on straight body
trucks for short hauls or on tractor
trailers for long hauls. The one-way
distance between packing plant and super-
market ranged from 105 to 330 miles. The
transport vehicles were all fully loaded
and the test containers were randomly
handstacked (unpalletized)at,the rear
of the vehicles where the ride was the
roughest. Driver competence varied as
did the suspension of the vehicles and
road conditions.
It is pointed out most strongly that,
although handling methods differed from
plant to plant and from supermarket to
supermarket, each master container of
eggs within each individual shipment was
handled the same as every other container
in that particular shipment to keep the
chances of damage to any one of them
equal,
After grading at the plant, the
master containers were placed on pallets
and moved to the cooler, Each pallet
held 20 containers--lO cases and 10
baskets. Half of the cases and half of
the baskets were cross packed, and the
remaining half were parallel packed.
These 20 master containers would make up
one shipment. After storage in the cooler
from 8 hours to 4 days, a pallet of eggs
would be transported to the loading dock
and handstacked randomly at the rear of
the delivery vehicle. This process was
repeated for all shipments.
At the retail store, the eggs were
unloaded at either street level or dock
height. Most shipments were unloaded
by 2- or 4-wheel handtrucks, and several
shipments were unloaded by conveyor belt.
The containers of eggs were moved to the
grading area of the supermarket and in-
spected,
After information on egg shell damage
was collected, data were subjected to
analysis of variance and Duncan’s multiple
range test to separate means. Statistical
significancewas at the five percent level
of probability.
Inspection Results
Although the following tables show
the rate of eggshell damage at the pack-
ing plants and supermarkets, only the
latter is being considered here. The
damage at the plant is shown only to
reflect the starting base upon which
additional damage within the distribution
network was added.
Table 1 shows the mean rate of egg-
shell damage by age of laying hen. The
percentage of checked eggs at the super-
market was significantly lower for eggs
which come from birds under 40 weeks old
(0.29 percent) than for eggs which came
from birds from 40-60 weeks old (1.7 per-
cent) and over 60 weeks old (2.02 percent).
There was no significant difference in the
rate of leakers between age groups.
Table 2 shows the mean rate of egg-
shell damage by season of the year. The
rate of checks and leakers was signif-
icantlylower for eggs that were produced
and shipped in the winter (0.79 percent
and 0.05 percent respectively) than for
eggs that were produced and shipped
Journal of Food Distribution Research June 78/page 20Table 1. Mean rate of eggshell damage by age of laying hen
Inspection Station
Age Packing Plant Supermarket Total
(weeks) Checks Leakers Checks Leakers Checks Leakers
Percent Percent Percent Percent Percent Percent
Under 40 0.85 0.10 0.29 0 1.14
40 - 60
0.10
2.81 .21 1.70 .15 4.51 .36
Over 60 2.78 .50 2.02 .18 4.80 .68
Table 2. Mean rate of eggshell damage by season of year
Inspection Station
Packing Plant Supermarket Total
Season Checks Leakers Checks Leakers Checks Leakers
Percent Percent Percent Percent Percent Percent
Summer 3.25 0.33 2.20 0.15 5.45 0.48
Spring-Fall 2.71 .19 1.44 .26 4.15 .45
Winter 1.59 .12 .79 .05 2,38 .17
during any other season of the year.
Eggs produced and shipped in the spring
and fall had a significantly lower rate
of checks (1.44 percent) than did eggs
produced and shipped in summer (2.20
percent). The difference in leakers
between spring-fall and summer was in-
significant.
Table 3 shows the mean rate of egg-
shell damage by two types of master con-
tainers and two stacking patterns within
each (pack). There were significantly
less checks to eggs which were cross
stacked in cases (1.28 percent) than
those that were parallel stacked in cases
(1.68 percent), There was no significant
difference in the rate of leakers, re-
gardless of pack.
Because damage is greater during the
warm months of the year than during the
cool months, Table 4, is shown to reflect
the rate of this damage based on the same
criteria as Table 3, except that Table 4
reflects damage only during the summer.
Note that the damage rates were greater
in the summer months, yet almost the same
relationship of damage rates between the
four packs was maintained with one ex-
ception. There was a significant dif-
ference not only between checked eggs
which were cross stacked in cases (1.57
percent) and checked eggs which were
parallel stacked in cases (2.52 percent),
but also between checked eggs that were
cross stacked in cases and those in both
basket patterns; i.e., shell eggs packed
cross tiered in cases had a clearly lower
rate of damage than eggs in the other
three packs.
The final objective of this study was
to compare the probability that checked
eggs at the plant would become leakers
during handling and distribution to the
supermarket with the probability that
sound eggs at the plant would become
June 78/page 21 Journal of Food Distribution ResearchTable 3. Mean rate of eggshell damage by two types of master containers and two
stacking patterns within each pack
Inspection Station
Packing Plant Supermarket Total
Pack Checks Leakers Checks Leakers Checks Leakers
Percent Percent Percent Percent Percent Percent
Basket:
Parallel 2.37 0.19 1.39 0.07 3.76 0.26
Crossed 2.75 .29 ‘ 1.58 .14 4.33 .43
Case:
Parallel 2.37 .23 1.68 .15 4.05 .38
Crossed 2.38 .17 1.28 .13 3.66 .30
Table 4. Mean rate of eggshell damage between packing plant and retail store during
the summer months, by type of pack
Inspection Station
Packing Plant Supermarket Total
Pack Checks Leakers Checks Leakers Checks Leakers
Percent Percent Percent Percent Percent Percent
Basket:
Parallel 3.23 0.27 2.28 0.13 5.51 0.40
Cross 3.21 .48 2.41 .29 5.62 .77
Case:
Parallel 3.26 .32 2.52 .10 5.78 .42
Cross 3.32 .24 1.57 .08 4.89 .32
Table 5. Sound-shell eggs and checked-shell eggs that became leakers between
packing plant and supermarket
Packing Plant Supermarket Leakers
Shell Condition Number Percent Number Percent
Sound 47,040 98 69 77.5
Checked 960 2 20 22.5
Total or Average 48,000 100 89 100.0
Journal of Food Distribution Research June 78/page 22leakers during those procedures. Table 5
shows that the 2 percent of checks at the
plant amounted to 22.5 percent of the
leakers at the supermarket. Therefore,
checked eggs at the plant were more than
10 times likely to become leakers than
sound eggs.
Conclusions and Recommendations
This study indicated that packing
materials and stacking patterns become
more critical to damage rates as the age
of birds increase and as climatic tem-
perature rises. Eggshells have higher
damage rates at both the packing plant
and the supermarket when the above condi-
tions are present. A clear difference in
damage rates exists, depending on the
stacking pattern of egg cartons in their
respective master containers.
When cartons are cross stacked in
paperboard cases in warm or hot weather,
checks are 38 percent lower than when
parallel stacked in cases, 35 percent
lower than when cross stacked in baskets,
and 31 percent lower than when parallel
stacked in baskets.
Therefore, as the propensity for
datige increases, the protection afforded
by cross stacking in paperboard cases
also increases to a significant extent.
The lower rate of damage to eggs
which are cross stacked in cases may not
be significant enough for users of
baskets to switch to cases. This is a
judgment which can only be made by the
users themselves based on their individ-
ual requirements, It is strongly recom-
mended, however, that packing plants and
supermarkets presently handling shell
eggs in cases ensure that those eggs are
cross stacked because of the significantly
lower rate of damage which prevails.
Another result of this study reflects
the high rate of leakers that develop
among eggs that were initially checked
at the packing plant. Although the total
rate of leakers at the supermarket check-
points was low, the losses generated by
those leakers are often quite high. Ex-
amples of this can be found in a 30-car-
ton master case which may have only 2 or
3 leakers near the top of the case. These
leakers are not only capable of making
other eggs in their respective cartons
undesirable from their exuding contents,
but very often manage to drip onto 10 or
15 other cartons underneath. In many in-
stances, those cartons which are damaged
on the outside by the leakers are con-
sidered a loss by the retail store and
are returned to the packer for credit.
The rates of checks and leakers dis-
cussed here have been small. However,
when the differences in damage rates are
projected over the entire shell egg in-
dustry, they add up to an appreciable
amount. Therefore, to keep damage to a
minimum, the most efficient stacking pat-
tern should be used. Also, keeping
checked eggs which leave the packing plant
to a minimum will significantly reduce the
rate of leakers which appear at the super-
market.
June 78/page 23 Journal of Food Distribution Research

PROTECTING SHELL EGGS BETWEEN PACKING PLANT AND SUPERMARKET

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