The physical location of antioxidants in oil-in-water emulsions can have significant influence on their free radical scavenging activity and ability to inhibit lipid oxidation. We aimed to determine the effect of the surfactant concentration on the partitioning behavior of tocopherols (α, γ, and δ) in oil-in-water emulsions. Tween 20 (0.1, 0.5, and 1%) increased the partitioning of the tocopherols into the aqueous phase via the formation of Tween 20-tocopherol comicelles. Partitioning behavior of antioxidants was dependent upon the number of methyl groups and, thus, polarity of the tocopherols. δ-Tocopherol (one methyl group) exhibited the most partitioning into the aqueous phase, while α-tocopherol (three methyl groups) had the lowest partitioning. Lipid oxidation studies showed that the antioxidant activity of δ- and α-tocopherols was enhanced by adding Tween 20 to oil-in-water emulsions. This work suggests that surfactant micelles could increase the antioxidant activity of tocopherols by changing their physical location.

The old-pressed oils (CPO) from grape seeds (GSO), flax seeds (FSO) and black cumin seeds (BSO) were analyzed for their fatty acid profiles, tocopherols, total phenolics, bioactives and phenolic compositions. The stability of CPO under thermal oxidation conditions was evaluated. The main fatty acid in FSO was linolenic acid (56.5% of total fatty acids); while GSO and BSO were rich in linoleic acid, which accounted for 66.8 and 56.8%, respectively. GSO was rich in ?-tocopherol (123.0 mg/kg), while ?-tocopherol was a prevalent isomer in FSO and BSO (137.9 and 128.9 mg/kg, respectively). The total phenolic contents in the oils ranged from 554 mg GAE/kg oil (FSO) to 1140 mg GAE/kg oil (BSO). Luteolin, dihydroquercetin and benzoic acids were the dominant bioactives and phenolics in FSO, GSO and BSO, respectively. Based on the oxidative stability index (OSI) value, BSO showed the highest value (6.14 h) among the other oils. The oxidative stability of FSO and BSO were higher than GSO according to peroxide value (PV) and conjugated diene (CD) values of the oils during storage at 60 °C. Hexanal, 2,4-heptadienal and (E,E)-2,4-heptadienal were the major volatile oxidation compounds (VOC) in FSO. Hexanal and (E)-2-heptanal were the main identified VOC in the GSO and BSO under the same oxidation conditions.

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High temperature application during drying of olive pomace before solvent extraction leads to formation of polycyclic aromatic hydrocarbons (PAHs) and their eventual presence in the oil. Therefore, the objective of this study was to investigate a mitigation possibility of PAHs in olive pomace oil. For this purpose, microwave pre‐treatment was applied to the olive pomace before drying at 200°C to final moisture content of less than 5%. Effect of pre‐drying microwave process was carried out against drying at 200°C and vacuum drying. PAH content analysis of the solvent extracted oil was completed using a HPLC method with fluorescence detection (HPLC‐FLD). The results demonstrated that the pre‐microwave application led to 75% reduction of total PAHs content in olive pomace oil. This study highlighted the possibility of an alternative innovative strategy to apply in a process to suggest a simple solution for a significant industrial problem. Practical applications: PAHs are serious problem in olive pomace oil. Removal of PAHs in olive pomace oil has a great importance because of their carcinogenic potential. Results show that PAHs are formed during drying of olive pomace at high temperature (200°C). This study reveals that microwave application was effective strategy to reduce PAHs in olive pomace oil. Therefore, drying process was modified with microwave pre‐heating application to produce high quality olive pomace oil. In this study, the effect of microwave pre‐heating application before drying to reduce PAH formation in olive pomace oil is demonstrated. The eventual reduction of total PAH concentration in olive pomace oil indicated the effectiveness of this pre‐heating application.

As emulsifiers become saturated on the surface of an emulsion droplet, any additional emulsifier migrates to the aqueous phase. Continuous phase surfactants have been shown to increase α-tocopherol efficacy, but it is unclear if this is the result of chemical or physical effects. The addition of α-tocopherol to an oil-in-water emulsion after homogenization resulted in a 70% increase of α-tocopherol in the continuous phase when sodium dodecyl sulfate (SDS) was at levels that were greater than the SDS critical micelle concentration. Conversely, when α-tocopherol was dissolved in the lipid before emulsification, continuous phase SDS concentrations did not increase. When SDS concentration led to an increase in the aqueous phase α-tocopherol, the oxidative stability of oil-in-water emulsions increased. Data indicated that the increased antioxidant activity was the result of surfactant micelles being able to decrease the prooxidant activity of α-tocopherol. Considering these results, surfactant micelles could be an important tool to increase the effectiveness of α-tocopherol.

Influences of chemical refining parameters on the removal of 15 polycyclic aromatic hydrocarbons (PAHs) from a list of 16 EPA‐priority pollutant PAHs are investigated. For this purpose, various process conditions for each refining stages (degumming, neutralization, bleaching, and deodorization) are applied to crude olive pomace oil and the changes in PAH concentrations are monitored using a high performance liquid chromatography with florescence detector. Results show that total PAH content of the oil is reduced effectively through all refining stages. Degumming has considerable effects on removal of individual PAHs depending upon water or acid application while the most significant reduction in total PAH is achieved when 1% water is used. Neutralization has a significant impact on removal of PAHs from the oil, however, washing steps have limited effects. Using various amounts (0.3, 0.6, and 0.9%) of activated carbon in 3% of bleaching earth are more effective on the reduction of total and heavy PAHs from the oil and the most reduction is achieved when 0.9% activated carbon is used. Deodorization is effective mainly on decreases in light PAHs while temperature incrementation does not have any significant impact on the reduction in total PAH content. Practical Applications: Olive pomace oil may include high amounts of PAHs. Because of their potential carcinogenic character, removal of PAHs from the oils has a great importance for oil acceptability. Results of this study provide information about the effects of process conditions of degumming, neutralization, bleaching, and deodorization on PAH reduction in olive pomace oil. These results might open up new process strategies in production of high quality olive pomace oil via refining. Crude olive pomace oil may include high amounts of polycyclic aromatic hydrocarbons (PAHs) which are carcinogenic and mutagenic, depending upon drying conditions of olive pomace before extraction. They need to be removed from the oil before consumption. In this study, effects of chemical refining parameters are investigated on the removal of 15 PAHs from olive pomace oil. All refining steps, mainly neutralization and active carbon application in bleaching, have significant impacts on reducing PAHs in the oil while increasing temperature during deodorization do not have considerable effect.