In 1952 the first withdrawal for ripening was made after 126 days 
of previous cold storage to determine the protective value of sealed 
polythylene film in prolonging the storage life of Bartlett pears. 
Fruit in the standard pack was almost full yellow in color, hard, mod- 
erately shrivelled, with a trace of pear scald upon removal from 31° 
F.; those in the sealed films were hght green in color, fresh in appear- 
ance, and free from pear scald. Pears in the standard pack scalded 
badly and developed severe core breakdown in 4 days without ever 
attaming acceptable dessert quality. Those in the sealed film ripened 
with a juicy texture and a good dessert flavor. The latter lots ripened 
with fair texture and fair flavor even after 160 days of cold storage but 
the shelf hfe of the ripened fruit was short and the dessert quality 
was distinctly inferior to that of pears ripened after 126 days at 31°. 
With an accepted cold storage life of 80 days for Bartlett pears 
in the standard _pack, the sealed film lengthened the storage period by 
approximately 7 weeks during which the fruit could be withdrawn and 
ripened with good dessert quality. The shelf-life of the ripened pears 
(table 4) was usually extended by several days in those lots of fruit 
which had been packaged in sealed film during prior cold storage. 
ANJOU PEARS 
Storage Physiology, Atmospheres, and Appearance 
Data on the firmness, soluble pectin content, and loss in weight of 
Anjou pears at different intervals of cold storage when packed in vari- 
ous sealed films and in oiled wraps are shown in table 5. Some experi- 
ments were made in 1949 to compare the protection afforded the fruit 
when a film was folded over the top of the pear pack instead of sealed ; 
tests also included trials of stretch wrapping the fruit in Phofilm 
TOD. 
The sealed films always provided greater protection for the fruit 
than did either the “fold-over” or stretch w1 rap. The degree of soft- 
ening and the percentage of soluble pectin of the fruit at 31° F. in 
folded film liners and in stretch wr aps approached that of the check 
lot; but these procedures did afford the fruit some protection against 
loss of moisture. The storage condition of the pears in all of the sealed 
films, as shown in table 5, was superior to that of the fruit in oiled 
wraps in the standard pack ; soluble pectin formation was ap- 
proximately one-half, and moisture loss was only a small fraction, of 
that of the fruit in the standard pack. The polyethylene films afforded 
the greatest protection against shrivel. 
Data on the carbon dioxide and oxygen levels in the atmosphere in 
the packages are given in table6. Some of the earher Phofilms (120P6 
and 120P4) studied in 1948 were nearly impervious to diffusion of the 
respiratory gases and tissue discoloration and flavor destruction in 
the Anjou pear resulted from their use. The heavy duty Phofilm 
100 HP also had a low gas transfusion rate and its use as sealed liners 
may result in injury to flavor of the Anjou pear (see later discussion 
of dessert quality). These films can be safely used when perfor aed 
but then the benefit from controlled atmosphere storage is lost. The 7 
FF, 80 and 100 FM1 Plhiofilms, 300 LSAT cellophane, and 100 ae 
Il 
a 
Ser ae Se a ee ee - 
