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Delta-7-stigmastenol: quantification and isomeric formation during chemical refining of olive pomace oil and optimization of the neutralization step

Drira, Malika, Jabeur, Hazem, Marrakchi, Fatma, Bouaziz, Mohamed
European food research & technology 2018 v.244 no.12 pp. 2231-2241
erythrodiol, food research, gas chromatography-mass spectrometry, neutralization, refining, sodium hydroxide, temperature, virgin olive oil
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.