Iarch 1951 Agricultural Economics Series No. 51-11
THE EFFECTS OF THE USt OF PERFORATED PAPER BAGS
AND COLORED WAX ON THE SHIPPING OF IRISH
POTATOES FROII DADE COUNTY, FLORIDA
L. J. Kushman, R. E. L. Greene, G. B. Ramsey
Associate Plant Physiologist, B.P.I.S.A.7., U.S. Department of Agricul-
ture, Meridian, .iississippi; Agricultural Economist, Florida Agricultural
Experiment Station, Gainesville, Florida; and Senior Pathologist, B.P.I.
S.A.E., U.S. Department of Agriculture, Chicago, Illinois, respectively.
Table of Contents
Summary . 1
Introduction . 2
Tests in Dade County, Florida . 2
1Methods of J.aking Study . 3
Results of Tosts .. . 5
Temperature . . 5
Loss in "Teight .. 5
Condensation . 5
Discussion of Results . . 7
Acknowledgments . 7
Report of a study in vhich certain phases were carried on
under the Research and Ilarleting tct of 1943.
This study was carried out as a part of Southern Regional
Project SU 5 "Spoilage in marketing Earl- Irish Potatoes". This
project is conducted in cooperation with the Agricultural Experi-
ment Stations of Alabama, North Carolina, South Carolina and Vir-
ginia, Burcau of Agricultural Economics and Bureau of Plant Indus-
try of the United States Department of Agriculture.
Department of Agricultural Economics
Florida Agricultural Experiment Sbation
Potatoes grown in Dade County are usually packed in a 3-ply moisture-
resistant 50-pound paper bag. Loads of potatoes in paper cool slowly because
of its insulating effect and the lack of air circulation through the load.
Since paper bags are tight containers, moisture condenses in thom as the temp-
erature drops, and they may become damp and subject to breakage during the un-
loading and handling in the terminal market.
In an attempt to get better temperature control and permit moisture to
escape from the bags more readily, a number of shippers in 1950 used bags that
were perforated with eight or twelve 3/8 inch holes. Hany of the potatoes
grown in the area were also treated with a wax containing a red color to give
the-i a more uniform color and appearance.
Special test shipments were made during the 1950 season of cars containing
perforated and non-perforated paper bags and a modified method of loading to
determine the effect of perforations on heat retention, loss in weight in transit
and bag breakage. Tests were also conducted to study the effect of waxing of
potatoes on spoilage and weight loss in transit. The results of these tests
1. Temperatures in perforated bags were slightly lower than in non perforated
bags but the difference was so small that little practical effect on decay
would be expected. Therefore, it is recommended again that potatoes placed
in paper be as cool as possible before filling the bags and loading the car.
2. There was a slight difference in weight loss in transit of potatoes pack-
ed in perforated and non-perforated bags, but it was not statistically
3. No significant difference in weight loss was found between waxed and non-
waxed potatoes either in transit or on holding.
4. Top layer bags lost the most weight in transit. These differences were
statistically significant at odds of 19:1.
5. Cooking quality of potatoes was not affected by waxing but the coloring
matter came off in the water and penetrated any exposed flesh when waxed
potatoes were boiled with the jackets on.
6. YWaxing did not change the effect of sprout inhibitors.
7. Consumer preference would appear to be the only benefit obtained in
adding colored wax to potatoes. This point is being studied.
A regional study is being conducted under the Research and T~rketing
Act to determine the factors that cause spoilage and economic losses in
marketing early Irish potatoes. Cooperating in this study are Alabama,
Florida, North Carolina, South Carolina, and Virginia and the Bureau of
Agricultural Economics and Bureau of Plant Industry, Soils and Agricultural
Engineering of the United States Department of Agriculture.
During 1948 and 1949, investigations were made in the principal potato
areas of each of the cooperating states to obtain data on factors that cause
losses in handling potatoes, Test lots were followed from harvesting, through
the grading and packing operations, to the terminal market and in many cases
to retail stores. Records were obtained on the weather conditions at the
time of harvest, method of handling potatoes in the field and packing shed
and other pertinent information. A series of salplos was collected from each
lot at various points in the marketing process to measure extent of damage
and determine where it occurred.
These investigations gave a good picture of current practices in hand-
ling potatoes in the various areas and showed the effect of these practices
on the condition and quality of potatoes as they reached the market. How-
ever, additional data were needed on certain points to supplement the infor-
mation obtained. Thoreforo, a number of controlled shipping tests were made
in 1950 to study the effects of special methods of handling and shipping
Tests in Dade County, Florida
1iost of the potatoes grown in Dade County are of the red varieties.
They are usually marketed during February, i'arch and April. Shipment to
market is usually by rail under standard ventilation. Tho weather en route
is generally cool or even cold depending on destination. Because of its
economy, a 3-ply moisture-resistant 50-pound paper bag is used extensively.
Only occasionally are burlap or cotton mesh bags used. Since paper bags are
subject to considerable breakage if loaded in the manner usually used for
burlap and cotton mesh bags, they are ordinarily loaded on their sides in
rows running the length of the car. The bags in each layer are offset some-
what over the ones below, thus leaving but little space for the air to circu-
late betwTeen them. The most common size loads for a railroad car are 600 or
720 fifty-pound bags which give loads five and six layers high respectively.
Loads of potatoes in paper bags cool slowly (1) because of the insula-
ting effect of the paper and the lack of air circulation through the load.
This is undesirable since high temperatures favor decay. Since paper bags
are tight containers, moisture condenses in them as the temperature drops,
and they become damp and subject to breakage during unloading and handling
in the terminal market. In an attempt to get better temperatures and permit
moisture to escape from the bags more readily a number of shippers, in 1950,
used bags that were perforated with eight or twelve 3/8 inch holes.
A wax containing a red color was applied to many of the potatoes to
give them a more uniform color and appearance. This material was used in
the Dakotas during the winter of 1949-50. In Florida, the wax was applied
during the packing process after the potatoes were washed but before they .
were dried. In addition to giving red potatoes a better appearance, there
was a possibility that waxing might reduce weight loss and decay.
Special test shipments containing perforated and non-perforated paper
bags and a modified method of loading were made to determine the effect of
perforations on heat retention, loss in weight in transit and bag breakage,.
Tests were also conducted to study the effect of waxing of potatoes on spoil-
age and weight loss in transit.
Methods of Making Study
In order to determine whether perforations aided cooling of the potatoes
and reduced condensation, two test cars containing perforated (12 holes per
bag) and non-perforated bags were shipped under standard ventilation from
Princeton, Florida to Chicago, Illinois and Cleveland, Ohio. Each car con-
tained 720 bags of potatoes, half of which were packed in perforated, and half
in non-perforated bags. The perforated bags were placed in the south end of
the car and the non-perforated bags in the north end. The car to Cleveland
went by way of Chicago and carried a standard, solid, offset type of load with
the tied ends of the bags to the walls. The other car went directly to Chicago
and contained a modified load wherein the bags were loaded lengthwise of the
car e xcept along the walls where the tied ends were placed next to the wall.
The bags in this load were placed directly over each other, instead of being
offset, to allow the perforations better access to air spaces between the bags.
Excelsior floor pads were used in both cars. The potatoes in each car were of
the Red Bliss variety. They were waxed at a rate of about 3 to 3 1/2 .
gallons of colored wax per car.
Six test bags were selected from: each lot and were placed about three
stacks in from the doorway in each end of the car. They were located by pairs
in the bottom (1st), middle (1th), and top (6th) layers of the load. In
addition, six bags of potatoes that were not'waxed were placed in each car..
Those were packed in perforated bags and placed next to the waxed potatoes
that were packed in perforated bags. All bags wore weighed at the shipping
point prior to loading and after arrival in the terminal market to determine
loss of weight in transit. Samples of potatoes were also held at the shipping
point to determine weight 'loss or decay.
1/ Rates of application varied from 2 to 5 gallons
per car load in the different packing sheds.
Temperatures en route were recorded by five Ryan recording thermometers
in the standard load, and three in the modified load. They were placed as
Location of Ryan Thermometer
Outside of car, under doorway
Layer 4, perforated bag
Layer 4, non-perforated bag
Bottom layer, non-perforated bag
Top layer, non-perforated bag
S I I
'- Non-perforated P
"' ~--(Conter of L
;\ ","-^ "-.
-,.. .. -
Perforated Paper Bag
(Center of Load)
i--. Bag (Top of Load)
/on-perforated Paper Bag
(Bottom of Load)
Fig. 1.- Trend of Temperature of Potatoes in Perforated and Non-Perforated 50-
pound Paper Bags, 720 Pag Typical Load, from Princeton, Florida. to
Chicago, Illinois, March 1950.
2/ Tape broke after second day. Record incomplete.
I r i
Results of Tests
Temperature data for the standard load are given in Figure 1. These data
show that the temperatures in the center layer of the load were consistently
about 2 to 30 lower in the perforated bags than in the non-perforated bags. The
small difference should be expected because in offsetting the bags in this type
of load the perforations are usually sealed by the bags above or below and
little air space exists in the load.o Unfortunately the temperature records for
the modified load were incomplete ./and only an indication mns obtained that
the temperature in the perforatedbag was dropping slightly faster than in the
non-perforated bags. This load shifted badly because of the difficulty in ob-
taining a tight load with lengthwise loading of the bags.
The temperature in the bottom layer of the standard load was 2 to 30 F.
lower than the top layer which in turn was 8 to 100 F. cooler than the center
of the load. This emphasizes the fact that heat as well as moisture moves
slowly from the center of such a solid load. It may be desirable to try double
deck cars if a satisfactory load could be worked out in order to provide fewer
layers of paper through which heat and moisture would need to go to escape.
Loss in VWight
The moisture or weight losses in the test bags are summarized in Table 1.
The average of each pair of bags at each position is given to minimize variations
duo to slight differences in decay, skinning, etc. In each of these tests the
non-perforated bags lost slightly less weight in transit than the perforated bags.
The average difference in weight loss was 0.33 percent which was not statistically
significant.3/This was true even though in both tests and position for position
the non-perforated bags averaged less weight loss than perforated bags.in the top,
middle and bottom layers. The difference in weight loss between layers was sig-
nificant,2/ however. On the average the top layer lost the most. The difference
in weight loss between waxed and non-waxed potatoes was very slight and not sig-
nificant and confirmed results of tests made with California early crop pota-
toes (2). No difference was found in the weight loss of waxed and non-waxed
samples held at shipping point, Table 2.
Inspectors in the terminal market indicated that there was a small amount
of condensation in all bags in the car containing the modified load. In the other
car containing the standard load, there was less condensation in the perforated
than in the non-perforated bags. Bag breakage was believed to be about the same
for the two types of bags. This was also true at the shipping point except early
in the season before the workers became accustomed to handling the perforated bags.
Decay was very slight in these tests and there was no difference between
perforated and non-perforated bags or between waxed and non-waxed potatoes.
Decay in holding tests at the shipping point was also very slight except in
Test io. 2. The potatoes in this test were Red Bliss that had been washed,
2/ Tape broke after second day, Record incomplete.
S/ At odds of 19:1.
Average Percentage 'Weight Lost in Transit of Duplicate Samples of
Potatoes Packed in Perforated and Non-Perforated 50-Pound Paper Bags,
and Waxed and Non-VWaxed Potatoes in Two Shipments from Princeton,
Florida to Chicago, Illinois and Cleveland, Ohio, arch 1950.
Percentage Loss in Weight
Standard Load : Modified Load Average
Position in : Non- :: Non- : Non-
: Bags : ags Bags ags s gs : Bags : Bags
Percent Percent Percent Percent Percent Percent
Top layer 2.53 2.22 1.74 2.62 2.14 2.42
middle layer 1.40 2.34 1.35 1.02 1.38 2.13
Bottom layer 1.56 1.72 2.01 1.95 1.79 1.83
Average 1.82 2.09 1.78 2.16 1.80 2,13
Top layer 2.56 2.53 2.55
Middle layer 1.54 1.35 1.45
Bottom layer 2.15 2.15 2.15
Average 2.08 2.01 2.05
Table 2.- Weight Lost in Holding Tests at Shipping Point of Waxod and
Holding : Type of : No. of : Time :.Percentage Weight Lost
Test No. : Container : Bags Held : Waxed : Non-Waxed
Number Hfours Percent Percent
1 / 50-lb. perforated paper 3 99 3.5 3.5
2 50-lb. cotton mesh 38
50-lb. cotton 2 70 1.4 1.4
4 / 50-lb. burlap 1 -- 2.9 3.1
4 / 100-lb. burlap 1 -- 4.5 4.1
1/ Decay interfered with weight loss reading.
2/ Shipped by Railway Express from Goulds, Florida to Meridian,
waxed very heavily 2/,. and not dried, and they were held in a closed
packinghouse over'a warm week end. Decay averaged 8.8 pounds per-bag
in five 50-pound bags..of .non-waxed potatoes, and 15.9 pounds in five 50-
pound bags of waxed potatoes. These results indicated that waxing may encour-
age decay development under certain conditions, but does not appear to influ-
ence decay as usually used commercially. Lenticel infection did not seem to be
increased by waxing as had been reported in California (2).
Discussion of Results
The cost of perforating the paper bags is about two dollars per thousand;
also probably a few more perforated than non-perforated bags are broken in
filling and handling at the shipping point. To justify this additional cost
definite improvement in temperature or moisture conditions would have to be
shown and this was not the case. Therefore, the earlier recommendation, (1)
that the potatoes be as cool as possible before filling the bags and loading
the car, is probably the best solution to improved transit environment.
Two objections were given to the use of red colored wax. Some people
dislike the artificial appearance given potatoes by the wax, especially if too
much wax was applied. The second objection is that applicators often did not
give a uniform coverage and the skinned areas took up less color than the un-
skinned areas. Waxing did not change cooking quality nor change the effective-
ness of sprout inhibitors. lThcn waxed potatoes were boiled in water with the
jackets on the red color came off in the water and penetrated any exposed
flesh. However, a more adequate survey is necessary to determine the consumer
reaction to color waxing. Such a survey is now underway.
The authors wish to express their appreciation for the cooperation and
help of producers and shippers in Dade County in making this study possible.
1. Kushman, L. J. and Johnson, J. I., "A Preliminary Report of the Southern
Regional Research Project on Spoilage in Marketing Early Irish Potatoes,
1949 and to some extent 1948 Season." i.iimeographod Report, Virginia
Agricultural Experiment Station, Blacksburg, Virginia.
2. Barger, U. R. and 17hiteman, T. Ii. "Waxing New Potatoes". Yearbook 5th
Annual fIeeting Kern County Potato Growers Association, Bakersville, Cali-
/ Il.uch more heavily waxed than even the heaviest commercial applications
Ag. Ec., Exp. Sta.