Aw. u, 1933 Internal Browning of the Yellow Newtown Apple 
181 
Tabi^® XI .—Effect of essential oils upon the permeability of apple tissue 
[Expressed in ohms resistance] 
The ini¬ 
Resistance at various intervals after 
the application of the essential oils. 
Treatment. 
tial re¬ 
sistance. 
After 5 
min¬ 
utes. 
After 10 
min¬ 
utes. 
After IS 
min¬ 
utes. 
After 20 
min¬ 
utes 
Control, no treatment (current on continu¬ 
ously). 
One drop of o.i per cent solution of amyl 
2, 900 
2, 800 
2, 800 
2,400 
2 , 200 
acetate. 
2, 800 
I, 600 
800 
550 
350 
One drop of saturated solution of amyl valer- 
iate. 
One drop of i per cent solution of acetalde¬ 
2, 900 
I, 600 
ij 000 
800 
600 
hyde. 
One drop of 0.001 per cent solution of amyl 
2, 900 
I, 600 
I, 000 
750 
500 
acetate. 
2, 900 
2, 000 
I, lOO 
900 
600 
One drop of 0.001 per cent solution of acetal¬ 
dehyde. 
2, 700 
2, 800 
2, 100 
I, 200 
900 
800 
Water about the electrodes. 
2, 400 
2, 200 
2, 100 
2, 000 
The figures in Table XI show conclusively that essential oils increase 
the permeability when brought in contact with fruit tissues* These 
data indicate also that only a very small accumulation of essential oils 
might be suflScient to increase the permeability of apple cells, allowing 
the oxidase and substrates to come in contact, thus resulting in the 
browning. This is especially true when the greatest dilutions of the 
substances used in these tests are compared with the normal essential 
oil content of some apples as given by Power and Chesnut {14), 
GENERAIy DISCUSSION 
In view of the relation of the browning with lower mean temperatures, 
it seems possible that the more severe browning of the mature fruit 
was due to exposure to the lower temperature whidi prevailed during 
the latter part of the harvesting season. The fruit of the second picking 
was exposed to a mean temperature of about 2.5° C. below the mean 
temperature of the growing season for three weeks after the fruit of 
the first picking was harvested. The fruit picked November 22 was 
exposed for six to eight weeks to the influence of a mean daily temperature 
of 2.5® to 8° below that prevailing at the time and before the first 
picking was made. As a whole, these data point to the possibility that 
the low temperature favors those conditions within the fruit which are 
necessary for the development of browning. This weakness in the 
fruit, if it can be considered as such, may be due to an abnormal develop¬ 
ment of the protoplasmic structure of the apples or to an accumulation 
of some deleterious substance which brings about a more rapid cessation 
in the normal functioning of these structures in storage. This seems 
probable since there was no appreciable difference between the resistant 
fruit and tiie fruit very susceptible to browning in constituents such as 
sugars, acid, and the Ph value of the expressed juice, which, it 
is generally believed, might influence a reaction of this sort through 
their effect upon the equilibria within the cells. 
