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.