o s s e m e n t , M. M i c h a u x , G. L o g n a y , I ? G i b o n and C. D e r o a n n e *The polymorphism of rapeseed oils with high and low erucic acid content was investigated using differential scanning calorimetry and X-ray diffraction. Both oils were hydrogenated to various iodine values. The f a t q acid pattern showed that erucic acid is slowly saturated. The melting curves were followed by DSC and pulsed NMR. For low iodine value the low erucic acid rapeseed oil exhibits a second melting peak owing to the appearance of new triglycerides with different properties. Samples of hydrogenated rapeseed oils were aged at 20°C and 29 "C. The short spacings determinations indicate that the p'+@ transition is faster for the low erucic acid rapeseed oil (LEAR) than for h e high erucic acid rapeseed oil (HEAR).
I n t r o d u c t i o nSince high erucic rapeseed oils are suspected of having negative medical effects on human beings, the fatty acid pattern of these oils has been changed for food applications by selecting new varieties of low erucic rapeseed 1-4. These new rapeseed oils are characterized by low levels of saturated fatty acids and a content of oleic acid reaching sometimes 60 oh. Moreover, they have a valuable content of poly-unsaturated fatty acids (30 to 35 %)5.Contrary to HEAR, when hydrogenated low erucic rapeseed oil shows a high tendancy to form "sandy" P crystals which are unacceptable for the margarine making. LEAR has also a very homogeneous fatty acid pattern with more than 90 0lo of C 18-acids. As a consequencc, the P'+P
Mit den entsprechenden Brom‐malonestern erhält man aus (Ia) die N‐Substitutionsprodukte (Ib) und (lc), die sauer zu (IIa) und (IIb) gespalten und dann mit Phosgen, Thiophosgen oder Di‐ brommethylenmethylimin (IIIc) zu (IVa) ‐ (IVc) kondensiert werden.
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