Characterization of grape seed and pomace oil extracts

Abstract

The objective of this study was to determine the nutrient and antioxidant contents of grape seed and pomace oil extracts from the main Turkish wine grape cultivars, Kalecik karas1, Narince, Hasandede and Emir. Dried and powdered seed and pomace materials were extracted with hexane. The results showed that the oil concentration of seeds ranged from 12.35 to 16.00% while in pomace the oil concentration varied from 5.47 to 8.66%. Grape seed and pomace oils were rich in oleic and linoleic acids and the degree of unsaturation in the oils was over 85%. α- tocopherol was the most abundant tocopherol in the oil extracts. Although γ and δ-tocopherols were found with low concentrations, β-tocopherol was not detected in the oil extracts. Oil extracts from pomace in all cultivars gave the highest tocopherol contents compared to the seeds. The contents of total phenolics were higher in pomace oil extracts than seed oil extracts. The highest total phenolic content (392.74 mg/kg) was found in the oil extract from Narince pomace compared to the other oil extracts. The refractive indexes of pomace oil extracts ranged from 1.445 to 1.468 while the refractive indexes of the seed oil extracts ranged from 1.460 and 1.466. In conclusion, wine byproducts including the seeds and pomace can be utilized both to get natural antioxidants and to obtain edible vegetable oil.