24 BULLETIN 803, U. S. DEPARTMENT OF AGRICULTURE. 
The color changes are remarkable and important. Green or yel- 
low colored olives, by suitable manipulation, emerged from the 
process with a uniform, pleasing black color. In fact, green-colored 
olives have a tendency to yield a blacker final product than purple 
olives. The best color, however, is probably developed in olives 
showing some red at first. Purple olives tend to lose their color 
and come out brown or even tan. The black color is developed by 
aeration accompanying alkali treatment, and there seems reason to 
suspect that the final black is due not to the original pigment sub- 
stance but to something developed during the pickling. The origi- 
nal colors turn a dirty brown or tan in the first caustic liquor. One 
of the factories has experimented with the addition of ferrous sul- 
phate to the wash waters, with the idea of fixing the color. The 
pits of the olives so treated have a marked black color. The results 
of this treatment have been unsatisfactory. 
SUMMARY. 
The results of the investigation here reported indicate that the 
best index of maturity for olives, both fresh and pickled, is the 
percentage of oil in the fruit flesh. Allowance, of course, must 
be made for variations due to the variety of the olives and the 
locality in which they are grown. A minimum oil content of 17 
per cent in the flesh is offered as a tentative standard of maturity for 
Mission olives and other common varieties, except the Manzanillo, 
Ascolano, and Sevillano. A minimum oil content of 15 per cent is 
recommended as a tentative standard for Manzanillo olives. No 
standards for maturity are recommended for the large-fruited 
olives, Ascolano and Sevillano, which must be gathered when rela- 
tively immature. These olives, however, should not be sold under 
the designation “ ripe.” 
Because of the great variations noted in the composition of olives 
of the same variety grown in different localities, it probably will 
never be practicable to set definite and hard fixed minima for oil in 
mature olives, and the proposed standards must be applied with 
caution. 
It was found that some of the abuses, the report of which led to 
this investigation, did exist, immature olives having often been 
pickled and colored to simulate pickled ripe olives. The data here 
given will make possible the detection of gross frauds of this nature. 
WASHINGTON : GOVERNMENT PRINTING OFFICE : 1919 
