Characterization of Fatty Acid Composition of some Selected Cold Pressed Seed Oils Grown in Turkey by Gas Chromatography
Huseyin Kara, Mustafa Topkafa, Hamide Filiz Ayyildiz
N.E.U. Faculty of Science, Department of Chemistry, Konya, Türkiye
 
Edible seed oils have been extracted by using different techniques such as solvent extraction, mechanical pressing and cold pressing. The cold pressing technique is a special procedure commercially used to produce edible oils and is preferred by consumers because it involves neither heat nor chemical treatments, and it is becoming an interesting substitute for conventional practices because of consumer's desire for natural and safe food products [1]. 
Cold pressed oils have more natural beneficial components such as natural antioxidants and phytochemicals than refined oils because of is not subject to any improvement process and health beneficial factors of food products for disease prevention and/or general health promotion through improved human nutrition.
This study focused on the determination of fatty acid composition of some selected cold pressed oils such as onion, okra, and carrots seed oils grown in Turkey. For this purpose, laboratory-prepared cold pressed seed oils were derivatized to methyl esters by base-catalyzed procedure [1]. Methyl esters were directly injected into HP-88 column (100 m x 0.25 mm x 0.25 µm) by using H2 gas as the carrier phase. The oven temperature was programmed as follows: 140°C (hold 2 min) to 200°C at 3°C/min and hold at 200°C for 25 min. Identification of the individual fatty acids was conducted by comparing GC retention time with that of the authorized pure individual commercial compounds.
The results showed that selected seed oils contain significant levels of unsaturated fatty acids which plays a determining role in their oxidative stability, with higher unsaturation associated with lower OSI. Namely, cold pressed carrots seed oil contained a very high content of oleic acid (18:1n-9) while cold pressed onion seed oil had linoleic acid (18:2). However, the cold pressed okra seed oil contained relatively equal amounts of stearic acid, oleic acid and linoleic acid.

KEYWORDS: Fatty acid composition, Cold pressed seed oils, Onion, Okra, Carrots

REFERENCE
[1]	Liangli L.Y., Kequan K.Z., John P., Food Chemistry (2005), 91, 723-729.
[2]	Topkafa M., Selçuk University (2013), Ph. D. Thesis.