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Olive oil

phytosterols, tracing of adulteration with hazelnut oil and chemical interesterification

Azadmard-Damirchi, Sodeif (2007). Olive oil. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2007:36
ISBN 91-576-7335-0
[Doctoral thesis]

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Abstract

Analyses of phytosterol classes of olive and hazelnut oils collected from different countries by TLC, GC and GC-MS revealed considerable quantitative differences. The composition of 4-desmethyl- and 4-monomethylsterols was similar in both oils, but 4,4'-dimethylsterols composition differed. Lupeol and an unknown (lupane skeleton) compound were exclusively present in hazelnut oil 4,4´-dimethylsterols and could be used as markers to detect virgin olive oil adulteration with hazelnut oil at levels below 4%. Conventional TLC to separate phytosterol classes has a low recovery rate and is time-consuming. A new SPE method to separate phytosterol classes was developed with stepwise elution by increasing the polarity of the n-hexane:diethyl ether solvent mixture. Comparison of the results obtained for hazelnut and virgin olive oils with those of TLC revealed that the SPE method was faster and gave higher sterol recovery rates. Free and esterified forms of sterols provide detailed information on the identity and quality of vegetable oils, and therefore 4,4´-dimethylsterols were investigated in hazelnut oil and virgin olive oil. A sample of solvent-extracted hazelnut oil was refined to monitor the effects of processing on 4,4´-dimethylsterol levels and on specific marker compounds. Of the refining processes tested, only neutralisation and bleaching considerably reduced 4,4´-dimethylsterols. In fully-refined hazelnut oil, losses of marker compounds in free form were higher than losses in their esterified form. GC-MS analysis showed that adulteration of olive oil with fully-refined hazelnut oil could be detected at levels of 2% by tracing lupeol in total/esterified forms of 4,4´-dimethylsterols. Olive oil has many applications in the food industry, e.g. blended with oils such as palm stearin to produce margarine or shortening by chemical interesterification. Investigation on lipid and minor lipid components of an olive oil-palm stearin blend during chemical interesterification showed that sterols were esterified with fatty acids at a higher level at 120 °C (7%) than at 90 °C (4%). Despite heat treatment and several steps to produce an interesterified product, there were minor losses in phytosterol and tocopherol contents and no significant increases in phytosterol oxidation.

Authors/Creators:Azadmard-Damirchi, Sodeif
Title:Olive oil
Subtitle:phytosterols, tracing of adulteration with hazelnut oil and chemical interesterification
Year of publishing :2007
Volume:2007:36
Number of Pages:53
Papers/manuscripts:
NumberReferences
ALLI. Azadmard-Damirchi, S., Savage, G.P. & Dutta, P.C. 2005. Sterol fractions in hazelnut and virgin olive oils and 4,4´-dimethylsterols as possible markers for detection of adulteration of virgin olive oil. Journal of the American Oil Chemists' Society 82, 717-725. II. Azadmard-Damirchi, S. & Dutta, P.C. 2006. Novel solid-phase extraction method to separate 4-desmethyl-, 4-monomethyl-, and 4,4´-dimethylsterols in vegetable oils. Journal of Chromatography A 1108, 183-187. III. Azadmard-Damirchi, S. & Dutta, P.C. 2007. Free and esterified 4,4´-dimethylsterols in hazelnut oil and their retention during refining processes. Journal of the American Oil Chemists' Society 84, 297-304. IV. Azadmard-Damirchi, S. & Dutta, P.C. 2007. Effects of chemical interesterification of an olive oil and palm stearin blend on lipids and minor lipid components. (Submitted)
Place of Publication:Uppsala
ISBN for printed version:91-576-7335-0
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:olive oil, adulteration, phytosterols, hazelnuts, plant oils, esterification, chemical composition, extraction, analytical methods
Keywords:adulteration, chemical interesterification, 4-desmethylsterols, 4, 4´-dimethylsterols, hazelnut oil, 4-monomethylsterols, olive oil, phytosterols, Solid Phase Extraction, SPE
URN:NBN:urn:nbn:se:slu:epsilon-1567
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-1567
ID Code:1412
Department:(NL, NJ) > Dept. of Food Science (until 161231)
Deposited By: Sodeif Azadmard-Damirchi
Deposited On:25 Apr 2007 00:00
Metadata Last Modified:02 Dec 2014 10:12

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