36 
Journal of Agricultural Research 
Vol. XXVII, No. r 
Coating the surface of the fruit, either with paraffin or with oil, reduces 
the permeability of the fruit skin in proportion to the amount of the 
coating material applied. This results in higher C0 2 concentration, 
and lower 0 2 concentration, in the gas present in the intercellular spaces 
of the fruit. If too much of the coating material is applied, anerobic 
respiration will result, with the development of disagreeable flavors in 
the fruit. 
Increasing the concentration of C 0 2 in the atmosphere surrounding 
apples results in a slower rate of softening of the apples. Coating the 
surface of the fruit with paraffin or oil also results in a slower rate of 
softening both in storage at 32° F. and at 70° F., probably by increasing 
the C0 2 concentration within the tissues. 
Coating the fruit, either with paraffin or oil, resulted in a reduced 
respiration rate, whether the fruit was being tested at 32 0 F. (o° C.), 
at 64.5° F. (18 0 C.), or at 8o° F. (26.5° C.); at 32 0 F. the ratio was 
less than 1, indicating that there was an abundance of 0 2 within the 
tissue, and that the reduced respiration rate was due to C0 2 accumu¬ 
lation. At 64.5° F., 0 2 within the tissues was practically exhausted, and 
some anerobic respiration apparently occurred in coated fruit, for the 
CO CO 
respiratory ratio —— 2 was greater than 1. At 8o° F. the ratio * was 
O2 o 2 
much greater than 1, indicating marked anerobic respiration. 
In normal, uncoated fruit the respiratory ratio at all temperatures 
was approximately 1, indicating that there was no anerobic respiration 
in any of the normal fruit studied. Rate of C 0 2 evolution in normal 
Winesap apples averaged 1.97 milligrams per kilogram hour at o° C., 
16.45 milligrams at 18 0 C., and 23.73 milligrams at 26.5° C. This appears 
to be very close to the ratio of the softening rates at the different tem¬ 
peratures. 
Atmospheres of C 0 2 in concentrations of 5 per cent, 10 per cent, 20 
per cent, and 50 per cent, with 20 per cent 0 2 , markedly inhibited the 
softening rates of apples, the retardation in softening rate varying with 
the C 0 2 concentration. Five per cent and io per cent concentrations 
of C 0 2 had no appreciable effect upon the flavor of apples. In concen¬ 
trations of 20 per cent C 0 2 there was a very slight flavor of fermentation. 
Fruit held in 50 per cent C 0 2 was entirely inedible. These tests were 
all made at 71.5 0 F. (22 0 C.). They indicate that any concentration of 
C 0 2 in which men can work, such as the concentrations of 2 to 3 per cent 
which may occasionally occur in cold-storage rooms, will not injure 
the fruit, and may, in fact, be distinctly beneficial, through retarding 
the softening process. 
LITERATURE CITED 
(1) Ballard, W. S., Magness, J. R., and Hawkins, L. A. 
1922. INTERNAL BROWNING OP THE YELLOW NEWTOWN APPLE. U. S. Dept. 
Agr.Bul. 1104, 24 p., 2 col. pi. 
(2) Bigelow, W. D., Gore, H. C., and Howard, B. J. 
1905. studies on apples. U. S. Dept. Agr. Bur. Chem. Bui. 94,100 p., 30 fig., 
5 pi. Bibliographical footnotes. 
(3) Brooks, Charles, Cooley, J. S., and Fisher, D. F. 
1919. apple-scald. In Jour. Agr. Research, v. 16, p. 195-217, 11 fig. 
(4) Browne, C. A., Jr. 
1899. A CHEMICAL STUDY OF THE APPLE AND ITS PRODUCTS. Pa. Dept. Agr. 
Bui. 58 46 p. 
