The content and composition of sterols and sterol esters in low erucic acid rapeseed (Brassica napus)

Characterisation of minor components in vegetable oil by comprehensive gas chromatography with dual detection

The profile of minor compounds, such as alcohols, sterols, free and alkyl fatty acids, waxes, etc., was investigated in different vegetable oils by a comprehensive gas chromatographic system, coupled with a simultaneous dual detection (flame ionisation detector and mass spectrometer) for quantitative and qualitative purposes. Such a system generated a unique two-dimensional chromatogram to be used as a chemical fingerprint. Multi-level information, due not only to a more "comprehensive" preparation technique, but also thanks to the exploitation of a more powerful and sensitive analytical determination allowed the extrapolation of diagnostic information from the minor components profile of different vegetable oils, along with their characteristic profile. Furthermore, an admixture of an extra virgin olive oil with a low amount of sunflower and palm oils was evaluated, attesting to the powerful diagnostic information provided by the proposed approach.

Fingerprinting of vegetable oil minor components by multidimensional comprehensive gas chromatography with dual detection

The potentiality of a multidimensional comprehensive gas chromatographic (GC × GC) method, employing a simultaneous dual detection (FID and mass spectrometer), to generate peculiar two-dimensional chromatograms to be used as a chemical fingerprint, was investigated to characterize minor compounds in edible oil, particularly olive oil. The best column combination for this application was investigated comparing two column sets (orthogonal or reverse-type), equivalent in terms of theoretical plate number, but differing in stationary phase combination. The apolar × mid-polar set gave a superior separation power, thus was used for further characterization. Different levels of information were extrapolated from the two-dimensional chromatogram. Using the FID, reliable quantification of the alkyl esters fatty acids and waxes was obtained, comparable to the results obtained using the official method, as required by the European legislation. However, thanks to a slight modification of the sample preparation method, the increased separation power obtained using the GC × GC method, and the support of the mass spectrometer detector, further diagnostic information was extrapolated considering the free sterol and tocopherol fractions. In particular, the profiles of extra virgin olive oil samples were compared with a hazelnut oil sample, highlighting that the latter was characterized by a larger number of compounds, completely absent in the extra virgin olive oil samples, which can be used to detect illegal admixtures.

Characteristics and composition of Parkia biglobbossa and Jatropha curcas oils and cakes

Parkia biglobbossa (PKBS) and Jatropha curcas (JTC) seeds were analysed for their proximate composition. The seeds oils were analysed for fatty acid, lipid classes, sterols and physicochemical characteristics. Proximate analysis revealed that the percentage crude protein, crude fat and moisture in PKBS were 32.40%, 26.525% and 10.18% respectively and 24.60%, 47.25% and 5.54% in JTC. Campesterol, stigmasterol, beta-sitosterol, Delta5-avenasterol and Delta7-stigmasterol were identified in the seed oils, but beta-sitosterol was most abundant, constituting 71.9% in JTC and 39.5% in PKBS. JTC oil had 72.7% unsaturated fatty acids with oleic acid predominating, while PKBS had 62% unsaturated fatty acids with linoleic acid being the most abundant. Results of lipid classes showed triglyceride as the dominant lipid species in the seed oils. Physicochemical analysis of the seed oils showed that they could be classified as semi drying oils and that they could be found applicable in alkyd resin and soap manufacture.

Characterisation and some possible uses of Plukenetia conophora and Adenopus breviflorus seeds and seed oils

Two non-conventional seeds, Plukenetia conophora (PKCP) and Adenopus breviflorus (ADB) were analysed for their proximate, fatty acids, sterols composition and physico-chemical characteristics. Crude protein was 25.65% for PKCP and 28.25% for ADB. ADB had lower moisture content (4.5%) than PKCP (8.0%) indicating that the former has better shelf life. Oil yields of the seeds were 49.58% for PKCP and 56.22% for ADB. The major sterols were stigmasterol and beta-sitosterol in PKCP and ADB respectively. PKCP oil had 98.8% unsaturated fatty acids with linolenic acid predominating (70.1%) while ADB had 85.1% unsaturated fatty acids with linoleic acid being most abundant (65.3%). The very high saponification and iodine values of PKCP oil suggest its utilisation in alkyd resin, shoe polish, liquid soap and shampoo production. There is the possibility of using ADB oil in these regards as well as for edible purposes.

Analysis of steryl esters in cocoa butter by on-line liquid chromatography-gas chromatography

On-line liquid chromatography-gas chromatography (LC-GC) has been applied to the analysis of steryl esters in cocoa butter. Separation of the steryl esters was achieved after on-line transfer to capillary GC. HPLC removes the large amount of triglycerides and pre-separates the components of interest, thus avoiding time-consuming sample preparation prior to GC analysis. The identities of the compounds were confirmed by GC-MS investigation of the collected HPLC fraction and by comparison of the mass spectra (chemical ionization using ammonia as ionization gas) to those of synthesized reference compounds. Using cholesteryl laurate as internal standard, steryl esters were quantified in commercial cocoa butter samples, the detection limit being 3 mg/kg and the quantification limit 10 mg/kg, respectively. Only slight differences in percentage distributions of steryl esters depending on the geographical origin of the material were observed. The patterns were shown to remain unchanged after deodorization. The method described might be a valuable tool for authenticity assessment of cocoa butter.

The content and composition of sterols and sterol esters in sunflower and poppy seed oils

The composition and proportion of free sterols and sterol esters in crude sunflower and poppy seed oils were determined, using preparative thin layer chromatography followed by gas chromatography with cholesterol as an internal standard. Free sterols and sterols esters were also isolated in a liquid fraction obtained by low temperature crystallization (-80 C) of the oils and enriched with minor lipid classes. This enrichment procedure provided a liquid fraction suitable for studies of minor components in the oils. However, selectivity towards sterol esters was observed since sterols esterified to very long chain fatty acids (C20-C24) were preferentially retained in the precipitate. The proportion of free and esterified sterols were found to be 0.34% and 0.28%, respectively, in the sunflower oil, whereas the corresponding figures for poppy seed oil were 0.33% and 0.05%. Sunflower oil was characterized by a relatively high percentage of delta 7-sterols, preferentially obtained in the esterified fraction, and by very long chain saturated fatty acids of sterol esters. The sterols in poppy seed oil were composed almost entirely of campesterol, stigmasterol, sitosterol and delta 5-avenasterol, although their percentage distributions were remarkably different in the free and esterified fraction.