Fatty acid composition, total phenols, and antioxidant capacity of grape seed oil (Vitis vinifera L.) extracted from different varieties

This study aimed to valorize grape seed residues from the wine industry by characterizing cold-pressed grape seed oil obtained from five Vitis vinifera L. varieties (“Malbec”, “Syrah”, “Italia”, “Moscatel”, and “Criolla”) collected in Arequipa, Peru. The structural and chemical characteristics of the grape seeds were analyzed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS). The fatty acid composition of the recovered oil was determined by gas chromatography–mass spectrometry (GC–MS), total phenolic compounds (TPC) were quantified using the Folin–Ciocalteu method and antioxidant capacity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Microbiological quality and a preliminary cost analysis were also assessed. The average oil yield obtained by cold pressing was 9.06% (90.64 g/kg of seeds). FTIR analysis confirmed the presence of functional groups mainly associated with lipids (C = O and C–H) and phenolic compounds (O–H), while GC–MS revealed that the oil was mainly composed of linoleic acid ethyl ester (64.40%), ethyl oleate (11.83%), and hexadecanoic acid ethyl ester (10.14%). Among the evaluated varieties, Syrah oil exhibited the highest total phenolic content (143.84 mg gallic acid equivalent/kg) and the highest antioxidant activity. Overall, DPPH radical scavenging values ranged from 33% to 46% among the analyzed oils. No microbiological growth was detected in the oil samples. The estimated production cost of grape seed oil was 25.58 USD per liter. These findings indicate that grape seed residues represent a sustainable source of value-added oil with antioxidant properties, which supports their potential application within a circular economy framework.