The sealed film box liner will retard the rate of ripening of pears even 
at room temperature. This fact, intelligently exploited by an in- 
formed retailer, can extend his merchandising period of the ripening 
pears without the need of reserve refrigerated space. 
DISCUSSION 
Packing pears in sealed plastic films at harvest is suggested for only 
that part of the crop intended for late storage, and should not be used 
to interrupt the orderly marketing program of each variety. Only 
sound fruit washed with an effective fungicide should be packed under 
film seal. The possibility of the development of decay in pears packed 
in the standard manner is very real; this possibility is increased with 
the use of the sealed film. The high relative humidity present in such 
packages is conducive to a more rapid appearance of decay than in the 
conventional pack. In only one season, however, was decay a serious 
factor in the film packaging of the experimental fruit in this study. 
That instance occurred in Anjou pears with an unusual number of stem 
punctures carrying an orchard infection of perennial canker (Veo- 
fabraea perennans). 
The condition and appearance of the fruit in cold storage is much 
improved when packed in sealed film. Moisture loss with evident 
shrivel is reduced; softening of the fruit, adverse color changes, and 
the development of pear scald are retarded. The retention of fresh- 
ness is much more pronounced in all varieties of pears under film seal 
than in those in the standard pack. 
The Phofilms 75 FF, 80 and 100 FM1, cellophane 300 LSAT, and 
polyethylene films 100 and 150, all can be safely used for packing pears 
in sealed box liners. These films will permit the accumulation of from 
1 to 3.5 percent carbon dioxide in the atmosphere surrounding the 
packed fruit at 31° F.; oxygen levels of 13 to 18 percent were ample 
for the successful cold storage of all the varieties of pears studied. 
The accumulation of low concentrations of carbon dioxide in the 
atmosphere definitely influenced the metabolism of the film-sealed 
pears in cold storage. Both respiratory activity and soluble pectin 
formation were retarded. Ulrich and Mimault (7) obtained similar 
results when paraflined pears were ripened. Trout, Hall, and Sykes 
(6) found that higher internal carbon dioxide levels rather than low 
internal oxygen concentrations were associated with the preservation 
of condition and the retention of flavor in apples. Extensive re- 
search (7, 3, 4,5) has demonstrated that the storage life of pears can 
be extended by an increase in the carbon dioxide content of the storage 
alr. 
Moisture losses in pears can be curtailed by the use of perforated 
film or by folding the top of the unperforated liner over the packed 
fruit. In these instances, however, accumulations of effective concen- 
trations of carbon dioxide are not possible and extension of the storage 
life through a retardation of the metabolism of the fruit is not at- 
tained. Therefore, it is very important that the films be sealed to 
obtain maximum storage protection. 
All of the data in this study show that the storage life of Bartlett, 
Anjou, Comice, and Bosc pears is lengthened when the fruit is packed 
in certain sealed films during long storage at 31° F. The data also 
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