Proximate composition
Total carbohydrates (43.59%) are the major component of silflower seeds
(Table 2) and most of it is contained in the hulls. Crude protein
(32.21%) is the second major component of the seed and found mainly in
the kernels. This value is comparable to what has been reported
(33.53%) previously (Kowalski and Wiercinski, 2004). The seed’s oil
content (17.69%) is lower than what was reported by
Kowalski and Wiercinski (2004),
but close to that of soybeans (17.9 to 23.1% at 10% moisture) grown in
different geographic locations (Breene et al., 1988). Linoleic acid
(62.32%) is the dominant fatty acid in silflower oil and accounted for
99% of the total polyunsaturated fatty acid (PUFA) (Table 3). The
second major fatty acid is oleic acid (19.62%) and accounted for 95.3%
of the total monounsaturated fatty acid (MUFA). Silflower oil also has
considerable amount of saturated fatty acids (SAFA) dominated by
palmitic acid (8.57%), with some myristic acid (3.79%) and stearic
acid (2.44%) also present. Overall, fatty acid composition is similar
to what was reported by Kowalski and Wiercinski (2004) and also within
the range of that of sunflower oil.
Another indicator of the degree of unsaturation or the number of double
bonds in the oil is given by its iodine value (IV). Highly saturated
oils, like coconut oil, have low IV (6 to 11) while highly unsaturated
drying oil like linseed oil have high IV (170 to 204) (Gunstone and
Harwood, 2007). Silflower oil’s IV (132) is the same level as sunflower
and soybean oils.