fruit (2%) as well as for Pineapple (1%) and Valencia oranges
(0.5%), the only three varieties for which data was available
during more than one season. These three varieties are the
major source of seeds for oil processing from the Florida citrus
industry.
 Dehulling.-Most oil seeds are preferably decorticated prior
to extraction of the oil. If the hulls are not removed from the
seeds before extraction, they may reduce the total yield of oil
by absorbing and retaining oil in the press cake and, in addition,
reduce the capacity of the extraction equipment. In practical
operation, the greatest yield of oil should be obtained by balanc-
ing the degree of separation of hulls and kernels. If an attempt
is made to separate hulls from the meats too cleanly, there will
be a loss of oil due to meats being carried over into the hulls.
If excessive proportions of hulls are left among the kernels,
there will likewise be an undue loss of oil from absorption by
the hulls (8). However, in some trials of continuous expelling
of the oil from Valencia orange seed kernels, it was shown that
the kernels did not press as well alone as when mixed with
shredded hulls (51).
 Reduction.-The extraction of oil from oil seeds, either by
mechanical expression or by solvents, is facilitated by reduction
of the oil bearing kernel to small particles or flakes (8). With
citrus seeds, solvent extraction of the oil has not been practiced
in the Florida industry, most of the oil being produced by ex-
pression in expellers or screw presses. (See Figure 1.) During
the preparation of oil seeds for expression in expellers, reduction
of the kernels, as in flaking, is not as necessary as for solvent
extraction, since heat is generated and seed particles are broken
up by the intense shearing stresses developed in the barrel of
the expeller (8).
 Cooking.-The primary objective of cooking oil seeds is to
increase the oil yield, particularly if the oil is expressed mechan-
ically. The moisture content of the seed may be controlled by
cooking, and is important to the yield of oil obtained. Very dry
seeds cannot be efficiently freed of their oil. The optimum mois-
ture of cooked oil seeds depends on the type of seed and the
method by which the oil is expressed. The optimum moisture
for expression of oil from citrus seeds is not known, but it has
been the practice to dry the seeds in a direct flame dryer to 6%
to 10% moisture prior to oil expression (37, 51). Cooking of dried
citrus seeds has not been practiced in Florida but would be rec-
ommended if the oil is expressed mechanically. This operation