34 
Journal of Agricultural Research 
Vol. XXVII, No, 
The decreased rate of softening of Delicious when held in various con¬ 
centrations of C0 2 was even more marked than that for Winesap. There 
was little softening in any lot held in concentrations of C0 2 of 20 per cent 
or more. Results for acidity change are less pronounced. The results 
as a whole for Delicious are rather less dependable than those for Winesap 
because of the lack of uniformity in the samples used. 
EFFECT OF C0 2 CONCENTRATION ON FLAVOR 
A number of apples from each of the above tests were tested for flavor. 
Concentrations of 5 and 10 per cent C 0 2 gave no flavor that was distinc¬ 
tive from that of control lots held in air. In the lot held in 20 per cent C 0 2 
most apples were normal, though in some fruit there was a suggestion of 
a flavor resulting from anerobic respiration. Apparently, 20 per cent C 0 2 
marked the extreme concentration in which apples can be held without 
serious impairment of flavor. Fruit held in 50 per cent C0 2 with 20 per 
cent 0 2 as well as fruit held in 100 per cent C 0 2 was entirely inedible. 
It is of much interest to note that the flavor produced in the apples in 
high C0 2 concentration, even in the presence of abundant 0 2 in the 
tissues, is very similar to that produced by partially sealing the fruit 
with oil or paraffin, and in many fruits was very similar to the flavor of 
water-cored apples. 
GENERAL DISCUSSION OF THE EFFECT OF COATING FRUIT, AND C0 2 
CONCENTRATIONS, UPON THE RIPENING PROCESSES 
It seems well established from the preceding data that coating the fruit 
with any material which retards gaseous exchanges will tend to retard 
softening and the development of a yellow color. This treatment results 
in a higher concentration of C 0 2 within the tissues as well as a decreased 
0 2 supply. At lower temperatures, coating the fruit moderately does not 
result in a lack of oxygen within the tissues, but the higher concentration 
of C 0 2 appears to directly retard the ripening processes. At higher tem¬ 
peratures both C0 2 accumulation and 0 2 deficiency may take part in 
retarding the ripening process. 
The fact that high concentrations of C0 2 , even in the presence of oxygen, 
gives a flavor to the fruit similar to that resulting from an absence of 0 2 
suggests that the action of the C0 2 may be to inhibit the oxydizing 
enzymes, and thus to stop or retard normal oxidation. 
INFLUENCE OF OILED PAPER WRAPS UPON RIPENING PROCESSES 
There is a widespread belief in the commercial apple trade that wrap¬ 
ping the apples in oiled papers, as has been extensively done for the con¬ 
trol of storage scald, results in a slower ripening of the fruit and a prolong¬ 
ing of the storage life (7). The above data on coating the fruit with oil or 
paraffin are very suggestive in this connection. 
The papers that have been used for wrapping to control scald carry 
a very high oil content. The oil will leave the paper very readily, as 
may be shown by placing an oiled paper over one that contains no oil. 
The oil will quickly spread to the non-oiled paper. The waxy coating, 
or cuticle, of apples appears to be exceedingly soluble in mineral oil. 
Consequently, heavily oiled paper loses a portion of its oil to the fruit 
wax. It has been noted that where sufficient oil has been used to control 
scald there is often a distinct appearance of oiliness on the fruit surface. 
