Jan. s, 1924 
Physiological Studies on Apples in Storage 
23 
If fruit is stored in closed barrels, the humidity of the storage room 
is not a very important factor. In open barrels or boxes, however, it is 
important to keep the humidity up to at least 85 per cent, to avoid 
shriveling the fruit. In more open containers, as baskets or slatted 
crates, it is very essential that humidity be kept sufficiently high. 
RELATION OF TIME OF PICKING TO LOSS IN WEIGHT 
Tests of the rate of loss of weight in storage as related to time of 
picking were made upon the three varieties, Ben Davis, Rome Beauty, and 
Delicious. There was no distinctive variation in loss of weight that could 
be associated with time of picking with the picking dates here used, 
namely, September 14 to October 10. It is a well known fact that fruit 
picked when extremely immature will wilt more readily than will well 
ripened fruit, but apparently the skin of the apples here studied was suffi¬ 
ciently cutinized by September 14 to prevent excessive moisture loss. 
EFFECT OF COATING THE SURFACE OF THE FRUIT WITH OIL OR 
PARAFFIN UPON THE RIPENING PROCESSES OF THE FRUIT 
During the normal respiration of fruit, oxygen is taken up from the 
air, and carbon dioxid given off from the fruit. The carbon dioxid is 
generated throughout the tissue, penetrates to the epidermis, probably 
largely through the intercellular spaces, which are relatively large in 
apple tissue, and passes out through the epidermis, while oxygen enters 
by a similar route. Consequently, the condition of the epidermis is of 
great importance in determining the concentrations of C 0 2 and of 0 2 in 
the tissues within the fruit. 
In order to determine the effect of coating the surface of the fruit, 
thereby reducing the permeability of the epidermis, certain lots of all 
varieties were coated when put in storage. Certain fruit was coated 
lightly with a non-drying, non-odorous oil, by wiping the surface of the 
fruit with a well oiled cloth. Other lots were coated with paraffin by 
wiping them with a solution of paraffin in a volatile solvent, the prepa¬ 
ration being one that has been widely advertised for applying to fruit in 
order to decrease wilting, to improve keeping quality, and to improve 
general market appearance. Fruits treated both with paraffin and with oil 
coating, and also check fruits, untreated, have been tested at intervals for 
hardness, for acidity, for color and general appearance, and for flavor. Res¬ 
piration experiments in which both oxygen absorbed and carbon dioxid 
given off were measured, have been carried out at various temperatures. 
Results of tests on the rate of softening of apples after coating with 
paraffin or with oil are somewhat variable, depending upon the variety 
used. At the end of the storage season coated Delicious apples were 
about as the checks which received no coating in hardness. Rome 
Beauty coated fruit was slightly harder than the check apples, York 
Imperial and Ben Davis were distinctly harder, and Winesap showed 
even a greater difference in hardness at the end of the season. This 
difference in hardness of the fruit was apparent when the fruit was with¬ 
drawn from 32 0 F. storage, and became more marked after the fruit had 
stood for 10 days at a temperature of 6o° to 70° F. Apples used as checks 
were similar in all ways to coated lots, except that they were not coated 
with any compound. Retardation of softening apparently varied 
directly with the quantity of oil paraffin on the fruit. If a very heavy 
coating was applied, the retardation was distinctly greater than if only 
a light coating was present. 
