Enriching kernel fraction by milling
The seeds (300 g/ batch) were milled using a 6-inch wide x 6-inch
diameter (15.24 cm x 15.24 cm) roller mill with 24 corrugations per inch
(9.4 corrugations/cm). The slow and the fast rollers have fixed speeds
of 358 and 804 rpm, respectively. Initially, the gap of the rollers was
set at 0.02 inch (0.51 mm). The milled seeds were then sifted through a
stack of 5-, 12-, 18-, and 25-mesh (4.0, 1.7, 1.0, and 0.7 mm) screens.
The fractions on 5- and 12-mesh screens (+5M and +12M) were
roller-milled again (with the roller gap reduced after each pass) to
recover more kernels still attached to the hulls and screened again. The
fractions retained on 18- and 25-mesh screen (+18M and +25M) were
aspirated to remove the light material, while the heavier fractions were
milled again to pass through the 25-mesh screen. The -25M fractions were
combined and defatted with hexane using a Soxhlet extractor. The
defatted enriched kernel meal was air-dried in the hood overnight and
stored in a capped glass jar under ambient conditions until used.