In this work, oil obtained from seeds of different red grape varieties, grown in the Autonomous Regions of Castilla-La Mancha and Murcia (Spain), was characterized by determining physicochemical and sensory quality parameters, stability, and the composition in fatty acids and sterols. The physicochemical quality parameters (free acidity, peroxide index, K 270 and wax) scored high (meaning low quality) compared with virgin olive oils, while the negative sensory attributes stood out over the positive ones. Therefore, the oil was not considered suitable for table use without undergoing a refining process. The samples showed high linoleic and low linolenic acid contents, while b-sitosterol was the main sterol found. Drying grape seeds with hot air before extraction gave higher physicochemical quality, total phenolic content and stability, and lower wax content in comparison to air-drying of seeds. The drying process affected the sterol composition but not the fatty acid composition.

The surpluses of the wine industry that originate from wine production in the European countries must be reduced. Green harvesting, consisting in collecting the grapes when they are still green, could contribute to the reduction of the yield of vineyards. The green grapes are not suitable for wine production, but they can be used for seed oil extraction. Grape seed oil is a linoleic acid rich oil that has been suggested as an alternative to traditional vegetable edible oils. In this work, grape samples were collected at different stages during berry development for seed oil extraction. The grapes collected at a very early stage showed a very low oil extraction yield compared with that of the samples collected at later stages. The oil from the grapes collected at an early stage had considerably higher sterols content and had a significantly different fatty acid composition compared with those of the oil extracted from grapes collected at later stages. However, the oil samples from grapes collected before veraison did not show significant differences with samples collected after veraison as regards oil extraction yield, fatty acids composition, and total sterol content and composition. Our data suggest that grapes collected from green harvesting near veraison could be suitable for seed oil extraction, with characteristics similar to those of the oil extracted from the seeds of mature grapes.