many cartons now use containerboard which is water resistant or has wet-strength 
properties. Racks and supported stacks are one solution for storage of corru- 
gated cartons. Duvekot (25) in Holland reported the results of 4 years' tests 
with 10 types of wooden storage boxes for apples and concluded that the best 
container was the standard fruit box with a complete corrugated liner. 
Many improvements have been made in the strength of cartons. Beardsell 
(7) showed that there is still a need for a container that is truly rigid when 
wet. Improvements in the form of coatings, laminations, extrusions, impregna- 
tions, and additives of various sorts are available. Supports within cartons 
could be added to give greater stacking strength, but these increase cost. 
Blanpied, Markwardt, and Ludington (8) tested various containers stacked 
10 high at 32° F. and 85 to 90 percent relative humidity for 6 months. After 
storage, fruit was removed and the containers compression tested for stacking 
strength. Corrugated box liners measurably increased the strength of lidded 
corrugated apple containers. Telescope corrugated containers had greater 
stacking strength than comparable regular slotted containers. 
Woodward (89) tested 11 containers of 3 types (wood, corrugated, and 
wirebound) for ability to protect apples from bruising. He found that apples 
in cell-packed cartons showed the least bruising, particularly in long-distance 
shipping. Apples in tray-packed cartons were second best, while jumble-packed 
apples in cartons showed the most bruising. Similar conclusions were reported 
for Sturmer apples in Tasmanian shipping tests by O'Loughlin (58), O'Loughlin 
and Shapman (59), and Chapman (17). Jacobsen (43) in Australia found signifi- 
cantly more bruising after shipment in wooden boxes (unlidded) than in jumble- 
filled cartons, and he recommended cartons for shipment of fruit to local mar- 
kets. A preliminary finding in shipping tests to London using 6 container 
types was that Jonathan apples in cell-packed cartons arrived in better condi- 
tion than in any of the other containers. In Sweden, Nyhlen (5/7) found that 
corrugated boxes caused less shipping damage than wood boxes and were easier to 
pack. 
Fountain (29) tested 1/8-inch thick polyurethane layer pads as a possible 
substitute for molded trays in corrugated cartons. The polyurethane pads were 
not adequate in thickness or density to protect apples from bruising. Bruising 
was considerably more serious with the plastic pads than with the conventional 
molded pulp trays. He also evaluated polystyrene (3/8-inch thick) foam layer 
pads for apples. However, these pads cracked, ruptured, and allowed excessive 
bruising compared with molded pulp trays. 
A lenticel injury on Golden Delicious due to formaldehyde given off by 
certain wet-strength agents used in the manufacture of molded-pulp trays was 
reported by Ginsburg (31). New formulations have eliminated the injury. 
Cooling Rate in Various Containers 
Considerable information is available on the cooling of apples in cartons 
Wood boxes were usually packed with a bulge which, when the boxes were stacked, 
left more sides exposed for cooling. The new telescope-type corrugated cartons 
had no bulge. When they were stacked tightly together in storage, cooling was 
very slow. 
Both Hall (36) and Sainsbury (72) have stressed that satisfactory cooling 
is not possible unless there is a good flow of air around containers to permit 
quick transfer of heat from fruit. Packages which do not have internal inter- 
ferences to airflow are cooled effectively by convection, If multiple packages 
3)7/ 
