Comparison of different methods for the pomegranate seed oil extraction.

Pomegranate (Punica granutum L.) seeds account for 10% of the total fruit weight and are mostly considered as a waste by food industry. The oil content in pomegranate seeds varies from 12 to 20%. This oil consists of the high content of polyunsaturated fatty acids mainly conjugated type, punicic acid. It possesses a wide array of biological properties - antidiabetic, antiobesity, antiproliferative, and anticarcinogenic activity.

Aim of this research was to compare the properties of pomegranate seed oil (from two different region of Dalmatia) obtained by cold extraction, the Soxhlet extraction and Accelerated Solvent Extraction (ASE). Oxidative stability of oils from pomegranate was determined using the calorimetric method (Differential Scanning Calorimetry). The determination of fatty acid composition was carried out by GC-FID analysis of fatty acid methyl esters. The positional distribution of fatty acids in the sn-2 and sn-1,3 positions of triacylglycerols was based on the ability of the pancreatic lipase to selectively hydrolyse ester bonds in the sn-1,3 positions. Sterols composition was determined with GC-MS.

The highest yield of oil was obtained using the Soxhlet method (12-15%) and the least with the ASE method (10-11%) but with significantly shorter time and minimum solvent usage. All extracted oils were rich in punicic acid (average 80%) and were characterized by good oxidative stability. Punicic acid was dominant in the external positions of triacylglycerols while in the internal positions there were oleic and linoleic acids.