Grape Seed Oil Characterization: A Novel Approach for Oil Quality Assessment

Abstract

The amount of organic pomace, left behind agricultural processes, is continuously rising in accordance with industrial progress. Grape pomace, generated in the wine industry all over the world, represents a raw material for obtaining valuable products. Grape seeds are especially rich in oil containing bioactive compounds that can have various health-related effects. The aim of the study is to compare the quality of seed oils obtained from six white grapes, including two Serbian autochthonous varieties. Linoleic acid, associated with numerous health benefits, is the major fatty acid in all samples (≈66% of total); α-tocopherol is the main tocopherol homologue. Total polyphenol content ranges from 73.4 to 104.3 mg of gallic acid equivalents per 100 g. In order to provide comprehensive information about antioxidant capacity of grape seed oil (GSO), three tests are performed (ferric ion reducing antioxidant power; 2,2’-diphenyl-1-picrylhydrazyl, and 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical scavenging). Antimicrobial activity is investigated against different strains; however, GSO inhibits the growth of Staphylococcus aureus and Candida albicans. Obtained results are used to develop a novel approach for oil quality assessment. Calculated oil quality scores (OQS) reveal no significant difference between international and autochthonous varieties, although Smederevka stands out as the most potent one. Practical applications: Considering the progressive waste increase in the wine industry and keeping in mind all health-promoting effects of grape seed oil (GSO), it is clearly observed that oil production represents a profitable and sustainable utilization of grape seeds. The results of the present study show that GSO is a rich source of compounds with antioxidant and antimicrobial properties. In addition, this work provides deeper insight into a quality of Serbian autochthonous grape varieties that are still insufficiently explored. Furthermore, the proposed oil quality score could be used as a comprehensive and unbiased method that enables quality assessment of oils. This tool can find practical application in comparing different plant oils regarding their compositional and functional properties. Finally, it would contribute to making some general oil intake recommendations.