Stereospecific analysis of triacylglycerols from vegetable oils by two procedures—II: Normal and high-oleic sunflower oils

Triacylglycerol stereospecific analysis of normal (NOS) and high-oleic sunflower (HOS) oils was carried out by two procedures to study the influence of variety and growing conditions. Four cultural varieties, two NOS and two HOS, were grown in seven different places of Italy. Three of the four varieties were grown both in dry conditions and with irrigation. Concerning the triacylglycerol fatty acid compositions, the results showed no significant differences between irrigated and nonirrigated samples (P>0.05), between the two NOS, and between the two HOS varieties. Between NOS and HOS varieties, only stearic acid showed no significant differences (P>0.05). The fatty acid compositions of the sn-2 position of NOS and HOS samples showed different percentage abundances (P<0.01), especially for oleic and linoleic acids. Fatty acid distributions in the sn-1 and sn-3 positions indicated a certain asymmetry. The relationships between the percentage intrapositional content of each acid (one sn-position at a time) and its percentage content in the original triacylglycerol matrix were studied. A general regression model was used to verify if the content of each acid at the three stereospecific positions changed at the same rate as the content in the intact triacylglycerols. The interpositional compositions of all varieties of NOS and HOS oils showed analogous trends for each acid.