Three commercially cultivatedNigella sativa seed varieties of Turkish origin were analyzed, and the characteristics and constituents of the seed oils were reported. Presence of lipase enzyme in seed results in enzymatic hydrolysis at ordinary temperature; the free acid content of oil may increase up to 40% or higher. Black cumin seed oil might serve as a source of semi‐drying oil and fatty acids of technical grade, and the removal of free fatty acids from oil and the recovery of fatty acids were investigated.
In this study, a systematic and detailed investigation on liquid‐liquid extraction of sulfur olive oil miscella in hexane with aqueous ethanol solutions was performed. Optimal extraction conditions for recovery of free fatty acids (FFA) with a minor loss of neutral oil were determined in bench‐scale single‐stage extractions. It was concluded that, to ensure deacidification with a low triglycerides loss, it is appropriate to extract the miscella with 30% or more dilute ethanol solutions. It was also noted that under these circumstances the free fatty acid percentage extracted is not affected by increases in contents of FFA and partial glycerides of sulfur olive oil, and the solvent must be saturated with hexane before extraction. Changing the oil:hexane ratio in miscella from 1:2 to 2:1 by weight did not have any significant effect on extraction results.
The characteristics of fatty oils recovered from seeds of four plant species of Turkish origin have been investigated. Seed oils ofRhus coriaria L. andEcballium elaterium (L.) A. Rich. showed a close resemblance to those of previously published reports. Oil extracted from the seed ofCeltis australis L. andGundelia tournefortii L. show characteristics similar to fruit oils of the plant families to which they belong. In the focus of their technological evaluation,Ecballium elaterium seed oil can be regarded as a typical drying oil, while the others show characteristics of semidrying oils.
In this study, laboratory-scale multi-stage cross-and counter-current extractions of sulfur olive oil miscella with 70 and 80% ethanol saturated with hexane were investigated. For cross-current extraction, the extraction factor for free fatty acids was constant in each extraction stage. Therefore, the extraction factors determined in single-stage extractions were used to calculate the extracted free fatty acid percentages for cross-current and counter-current multi-stage extractions and results were in close agreement with the experimental data. It was possible to determine the amount of solvent and the number of stages required for counter-current extraction to remove the desired amount of free fatty acids from a given sulfur olive oil with 70 or 80% ethanol. Comparison of the results for these two solvents showed that 80% ethanol was more suitable.
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