Delta-7-stigmastenol: quantification and isomeric formation during chemical refining of olive pomace oil and optimization of the neutralization step
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The aim of this study is to evaluate the formation of the increase of Δ-7-stigmastenol during the chemical refining of pomace olive oil (POO) and the optimal neutralization by NaOH concentration of 20 °Be at a temperature of 70 °C. A comparison has been made between virgin olive oil (VOO) and consecutive steps of refining process in the amounts of Δ-7-stigmastenol of the POO oil samples. Among the oils, refined olive oil particularly the neutralized olive oil (NOO) by soda (NaOH) contained a high-level of Δ-7-stigmastenol. A mean result found in NOO by different concentration of NaOH from 15 to 25 °Be showed increased values significantly (p < 0.05) from 0.70 ± 0.01% to 0.78 ± 0.01% of Δ-7-stigmastenol and increased significantly (p < 0.05) the levels of erythrodiol and uvaol from 26.34 ± 0.39% to 28.11 ± 0.42%. Then, the concentration of the ∆-7-stigmastenol was evaluated using a GC–MS instrument. Besides, further analyses were performed to ensure the uniqueness of the peak of Δ-7-stigmastenol and absence of any overlap. In all cases, the level of Δ-7-stigmastenol was higher than the limit set by the International Olive Council.
KeywordsΔ-7-Stigmastenol Chemical refining processes Neutralization Optimization GC/MS
Virgin olive oil
Refined pomace olive oil
Free fatty acids
Gas chromatography/mass spectrometry
International olive council
Neutralization olive oil
The authors would like to thank the “Ministère de l’Enseingement Supérieur et de la Recherche Scientifique, Tunisia LR14ES08” and “Ministère de l’Agriculture et des Ressources Hydrauliques, Tunisia” for the support of this research work. The authors acknowledge also National Funds through Ministry of Higher Education-Tunisia for financing MedOOmics Project—“Mediterranean Extra Virgin Olive Oil Omics: profiling and fingerprinting”—“Arimnet2/0001/2015”, Strategic Projects UID/AGR/00115/2013. The authors would like also to thank Madam. Mariem DRIRA for English correcting of this manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
Compliance with Ethics requirements
This article does not contain any studies with human or animal subjects.
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