8 
which the pressing is carried. Factors affecting the degree to which 
the fat is expelled in the press (or conversely the quantity of fat 
left in the press cake) are: (1) The actual pressure exerted per 
square inch of cake surface, (2) the temperature at which the 
pressing is conducted, and (3) the length of time during which the 
pressure (and temperature) are maintained. The thickness of the 
layer of liquor pressed and the type of press-mat used also may 
affect the quantity of butter obtained. 
Cocoa presses are commonly operated with a pressure on the 
hydraulic ram of from 5,000 to 6,000 pounds per square inch. In 
the giant presses, capable of producing the driest press cake, the 
ram ma} 7 be as large as 19 inches in diameter, a diameter greater 
than that of the pots in which the chocolate liquor is pressed. The 
actual pressure per square inch of cake surface in such presses may 
therefore exceed 6,000 pounds. 
The temperature at which the liquor is maintained during ordi- 
nary cocoa pressing is about 60° C. (140° F.) ; and probably 40 
minutes is the average pressing time. Higher pressing tempera- 
tures, though tending to increase the yield of cacao butter, are said 
to injure the quality of the cocoa. When the highest practicable 
yield of the butter is the chief consideration, however, that is, when 
the cake being made is low-grade or by-product cake, its quality is 
of no moment. Some of the driest low-grade cake encountered is 
said to have been pressed at a temperature of 90° C. or more for 
from 55 to 60 minutes. It is claimed that this higher temperature 
does not injure the quality of the cacao butter. 
The liquor from freshly roasted nibs contains only about 1.5 
per cent of moisture (26), so the loss in weight during pressing, 
due to evaporation, must be almost negligible. It follows that 
in ordinary factory practice the sum of the weights of the butter 
and cake obtained very nearly equals the weight of chocolate liquor 
pressed. 
The following data on the theoretical yields of butter and press 
cake from 100 pounds of average roasted nibs or liquor show the 
effect of different degrees of pressing. Assuming that the freshly 
roasted nibs contain 1.5 per cent of moisture and 53 per cent of 
fat, and that the press cakes contain 2 per cent of moisture, Table 
1 gives the theoretical yields of butter and cake per 100 pounds 
of roasted nibs or liquor. 
Table 1. — Theoretical yields of cacao butter and cocoa cake per 100 j)ounds of 
nibs liquor 
[The theoretical loss of moisture amounts to 0.30 to 0.46 pound] 
Degree of pressing (fat left in press cake) 
Yield of 
cacao 
butter 
Yield of 
press cake 
(moisture 
2 per cent) 
Dry-pressed cake, containing 10 per cent fat. 
Pounds 
47.83 
46.04 
44.78 
43.45 
89.83 
Pounds 
51. 71 
Dry-pressed cake, containing 13 per cent fat. . 
53.53 
Cake containing 15 per cent fat . . 
54.82 
Average low-grade cake, containing 17 per cent fat 
56. 17 
"Breakfast cocoa" cake, containing 22 per cent fat 
59.87 
