155 
The following table gives the results of a similar experiment in which 10 cubie 
centimeters of the oil to be tested were inoculated with a drop of moldy oil, 
then poured out in a Petrie dish, which was placed in a closed specimen jar 
over a little moist, moldy copra, and allowed to stand in the incubator at 33° 
to 35° C. for one week: 
Initial One week 
Nature of oil. acidity. gic ene my 
DO eae aecan see ees. 0,10 | 0. 50 
IND; SU ceeen Seats ok. he 0.10 0, 21 
No. 30 + 1 per cent ‘“latic” 
+ 1 per cent water __._____- 0.10 8. 63 
The last sample, which showed the greatest increase in acidity I have 
yet been able to produce in a short time, was almost completely covered 
by a greenish-yellow mold, similar to that noticed on copra, and it had 
the characteristic odor of a rancid oil. 
In the light of these latter experiments there can be no doubt of the fact 
that coconut oil, provided it contains sufficient moisture and nutrient 
matter, is attacked by micro-organisms, principally molds, with an accom- 
panying production of free acid and of a disagreeable taste and odor. 
This is the principal cause of “rancidity” in coconut oil, if by “rancidity” 
we mean a high acid content and a bad taste and odor. Whether this fat 
splitting is directly due to a life process of the molds or to an enzyme 
secreted by them is a problem which has not yet been solved. However, 
it seems highly probable that these molds produce a slowly acting enzyme, 
soluble in oil, which continues its hydrolytic action even after the or- 
ganisms themselves are dead. This would account for the steady increase 
in free acid of some commercial oils which are perfectly clear and free 
from impurities and which have been proven to contain no living bacteria 
or molds. Experiments are now being carried on to clear up this point. 
OTHER FACTORS INFLUENCING THE ACIDITY OF OIL. 
Effect of sunlight—Twenty-five cubic centimeters each of samples “A” 
and “11” (see table, p. 119) were placed in 50-cubie centimeter glass- 
stoppered bottles and allowed to stand in the sun for one month. At the 
end of this time “A” contained 0.22 per cent and “11” 0.24 per cent of 
free acid, while at the same time the original samples “A” and “11” 
showed 0.06 and 0.18 per cent, respectively. No marked change in taste 
or odor could be detected. The acid content of the pure sample “A” 
appears to have increased considerably more than that of “11,” due 
probably to its contamination with a few drops of water during a heavy 
rain. However, the total amount of acid developed was so small that 
the experiment was not repeated. 
Effective of heat and moisture.—Several samples of oil were heated 
at 100° for periods up to twenty-four hours with no change in acid 
