Composition of the sterol dehydration products in refined olive oil
1995
Grob, K. | Biedermann, M. | Bronz, M. (Kantonales Laboratorium, Zurich (Switzerland)) | Mariani, C. (Stazione Sperimentale per le Industrie degli Olii e Grassi, Milan (Italy))
The concentration ratio of the sterol degradation products stigmastadiene/campestadiene (R1) in refined olive oils may be substantially lower than that of sitosterol/campesterol. Factors were investigated which could contribute to this deviation. Using on-line LC-LC-GC with an apolar GC capillary column, the deviation did not seem to be the result of a campestadiene peak significantly enlarged by a interfering component. Stigmastatriene, on the other hand, was often coeluted with a large component, probably a dehydration product of 24-methylene cycloartenol. Decomposition of sterols and their esters was investigated by addition of free or esterified soybean sterols to lard and treatment with earth (imitating decoloration) or imitating deodorization. Campesterol and its esters were degraded up to almost 50% more rapidly than sitosterol. Pressed olive oils of extra virgin and lampante quality as well as solvent-extracted olive oil were treated at varying intensity. For oils obtained by pression, R1 corresponded to the recommendation of the International Olive Oil Council (IOOC), i.e. R1 exceeded 15 whenever the stigmastadiene concentration exceeded 4 mg/kg. Lower values for R1 were observed at conditions producing small amount of sterenes and for husk oil
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