Physical properties and processing of Silphium integrifolium seeds to
obtain oil and enriched protein meal
Silphium integrifolium Michx. (Silflower) has been a promising subject
for domestication as a perennial oilseed crop. This work was carried out
to investigate the seed processing aspect of this effort. Selected
physical properties of the seed were evaluated, seed milling to obtain
enriched kernel fraction was conducted, and initial characterization of
the seed protein was performed. There was wide variation in flat seed
length (11.54 to 20.75 mm), width (4.61 to 11.76 mm), and thickness
(0.92 to 1.63 mm). The thousand seed weight was 23.8 g but the tapped
bulk density was only 189.58 g/L due to the presence of wing around the
seed’s periphery. The kernel accounted for 56.14% of the seed weight
and contained 31.00% oil. An enriched kernel fraction with 79.6%
purity was obtained by roller-milling, sifting, and air classification.
Linoleic (62.3%) and oleic (19.62%) acids were the major fatty acids
in the oil. The defatted enriched kernel fraction contained 63.41%
crude protein. Globulin, glutelin, albumin, and prolamin accounted for
55.63%, 19.28%, 16.38%, and 8.71% of the soluble proteins,
respectively. At an extraction pH of 9, protein solubility was 62%.
Maximum solubility (70%) was obtained at pH 10 while minimum solubility
of 9% occurred between pH 4 and 5.5. Aside from the oil, the dehulling
of silflower seeds also produced a high-protein defatted meal, which may
be used as is or as a starting material for enriching the protein
further into a protein isolate.